WO2024065174A1 - 光发射机、光发射方法、光模块、设备及系统 - Google Patents

光发射机、光发射方法、光模块、设备及系统 Download PDF

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Publication number
WO2024065174A1
WO2024065174A1 PCT/CN2022/121716 CN2022121716W WO2024065174A1 WO 2024065174 A1 WO2024065174 A1 WO 2024065174A1 CN 2022121716 W CN2022121716 W CN 2022121716W WO 2024065174 A1 WO2024065174 A1 WO 2024065174A1
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WIPO (PCT)
Prior art keywords
wavelength
light
modulation
optical
unit
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PCT/CN2022/121716
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English (en)
French (fr)
Inventor
李芮
王建峰
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华为技术有限公司
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Priority to PCT/CN2022/121716 priority Critical patent/WO2024065174A1/zh
Publication of WO2024065174A1 publication Critical patent/WO2024065174A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters

Definitions

  • the present application relates to the field of optical communication technology, and in particular to an optical transmitter, an optical transmission method, an optical module, a device and a system.
  • the optical transmitter is an important module in optical communication equipment.
  • the optical transmitter includes a light source and a modulation unit.
  • the light source is used to provide a wavelength of light to the modulation unit, and the modulation unit is used to modulate the light to obtain the optical signal that the optical communication device needs to transmit.
  • the optical transmitter switches the wavelength of the optical signal.
  • the light source of the optical transmitter switches the wavelength of the light provided to the modulation unit, and the optical transmitter needs to adjust the bias voltage of the modulation unit according to the wavelength of the switched light so that the modulation unit can modulate the light after the wavelength is switched.
  • the optical transmitter not only needs to switch the wavelength of the light provided by the light source, but also needs to adjust the bias voltage of the modulation unit. Therefore, the process of switching the wavelength of the optical signal by the optical transmitter is relatively complicated.
  • the present application provides an optical transmitter, an optical transmission method, an optical module, a device and a system, which can solve the problem that the process of switching the wavelength of an optical signal of the optical transmitter is relatively complicated.
  • an optical transmitter comprising: a light source, a switch unit, a modulation unit and a control unit.
  • the light source is used to provide light of multiple wavelengths to the switch unit;
  • the control unit is used to control the switch unit to output light of a first wavelength among the multiple wavelengths to the modulation unit in a first time period, and to control the switch unit to output light of a second wavelength among the multiple wavelengths to the modulation unit in a second time period;
  • the modulation unit is used to modulate the input light of the first wavelength in the first time period to output modulated light of the first wavelength, and to modulate the input light of the second wavelength in the second time period to output modulated light of the second wavelength.
  • the difference between the first wavelength and the second wavelength is an integer multiple of a free spectral range (FSR) of the modulation unit, for example, the difference between the first wavelength and the second wavelength is the FSR.
  • FSR free spectral range
  • the light source can provide multiple wavelengths of light to the switch unit, and the control unit can control the switch unit to output the first wavelength or the second wavelength of the multiple wavelengths to the modulation unit, so that the modulation unit can modulate the received light. Since the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit, and the wavelength of the light input to the modulation unit by the switch unit can be switched between the first wavelength and the second wavelength, when the optical transmitter needs to switch the wavelength of the optical signal between the first wavelength and the second wavelength, the modulation unit does not need to change the bias voltage, and the light source does not need to change the light provided.
  • the control unit only needs to control the switch unit to output the light of the switched wavelength. It can be seen that the process of switching the wavelength of the optical signal of the optical transmitter is relatively simple.
  • the control unit controls the switch unit to switch the wavelength of the output light at a faster speed. Therefore, the optical transmitter switches the wavelength of the optical signal at a faster speed, and the optical communication device where the optical transmitter is located switches the wavelength of the emitted optical signal at a faster speed.
  • the time for the optical transmitter provided in the present application to switch the wavelength of the optical signal can be controlled within 50 milliseconds, which can achieve "seamless connection" of the service without affecting the continuity and consistency of the service.
  • the switch unit when the above-mentioned switch unit is a switch unit based on the thermo-optical effect (which can be called a thermo-optical switch), the time required for the optical transmitter to switch the wavelength of the optical signal is in the millisecond level; when the above-mentioned switch unit is a switch unit based on the electro-optical effect (which can be called an electro-optical switch), the time required for the optical transmitter to switch the wavelength of the optical signal is in the nanosecond level.
  • the time required for the optical transmitter to switch the wavelength of the optical signal provided in the embodiment of the present application is reduced by a thousand times or even a million times.
  • the optical transmitter includes a modulation unit as an example. It can be understood that the optical transmitter can also include multiple modulation units; the FSR of different modulation units can be the same or different.
  • the multiple wavelengths include: multiple wavelength groups corresponding to the multiple modulation units. For a wavelength group corresponding to a modulation unit, the wavelength group includes a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit. Different wavelength groups can be the same or different, the first wavelengths in different wavelength groups are different, and the second wavelengths in different wavelength groups are different.
  • control unit is used to: control the switch unit to output the first wavelength of light in the corresponding wavelength group to the modulation unit in a first time period, and control the switch unit to output the second wavelength of light in the corresponding wavelength group to the modulation unit in a second time period.
  • each wavelength group may not include other wavelengths, or may include other wavelengths, which is not limited in the embodiments of the present application.
  • the difference between any two wavelengths in the wavelength group may be an integer multiple of the FSR of the modulation unit corresponding to the wavelength group.
  • the light source, the switch unit and the modulation unit may have multiple implementable modes.
  • the multiple implementable modes of each part of the light source, the switch unit and the modulation unit will be introduced respectively below.
  • the light source may include a quantum dot mode-locked laser (QDMLL), a quantum well mode-locked laser (QWMLL), an optical frequency comb or a light source pool.
  • QDMLL quantum dot mode-locked laser
  • QWMLL quantum well mode-locked laser
  • the switch unit may have an output port, and the switch unit is used to output light from the output port to each modulation unit. For example, in a first time period, the switch unit is used to output light of a first wavelength in a wavelength group corresponding to the modulation unit from the output port to each modulation unit. In a second time period, the switch unit is used to output light of a second wavelength in a wavelength group corresponding to the modulation unit from the output port to each modulation unit. This situation is applicable to the case where the optical transmitter includes one or more modulation units.
  • the switch unit has a plurality of output ports corresponding to the plurality of modulation units one by one, and the switch unit is used to output light from the output ports corresponding to the modulation units to the modulation units. For example, in a first time period, the switch unit is used to output light of a first wavelength in a wavelength group corresponding to the modulation unit to the modulation unit from the output port corresponding to the modulation unit. In a second time period, the switch unit is used to output light of a second wavelength in a wavelength group corresponding to the modulation unit to the modulation unit from the output port corresponding to the modulation unit.
  • the switch unit has one output port, which is applicable to the case where the optical transmitter includes one or more modulation units.
  • the first implementation of the switch unit can be combined with each implementation of the light source.
  • the switch unit includes: a first wavelength demultiplexer (DEMUX) and a first wavelength division multiplexer (MUX), and at least one optical switch group corresponding to the at least one modulation unit; the output port of the switch unit is the output port of the first MUX; for the one modulation unit: the first DEMUX is used to receive the light of the wavelength group corresponding to the modulation unit; the optical switch group corresponding to the modulation unit includes: a plurality of optical switches corresponding to the wavelengths in the wavelength group; the first DEMUX is used to transmit the light of each wavelength in the wavelength group to the corresponding optical switch; in a first time period, the control unit is used to control the optical switch corresponding to the first wavelength in the optical switch group to be turned on, and control the optical switch not corresponding to the first wavelength in the optical switch group to be turned off; in this way, the light of the first wavelength in the wavelength group is transmitted to the first MUX and then output to the modulation unit, while the light of other wavelengths in the wavelength group except the first wavelength
  • the control unit is used to control the optical switch corresponding to the second wavelength in the optical switch group to be turned on, and to control the optical switch in the optical switch group that does not correspond to the second wavelength to be turned off; in this way, the light of the second wavelength in the wavelength group is transmitted to the first MUX and then output to the modulation unit, while the light of other wavelengths in the wavelength group except the second wavelength cannot be transmitted to the first MUX and output to the modulation unit.
  • the switch unit has one output port, which is applicable to the case where the optical transmitter includes one or more modulation units.
  • the second implementation of the switch unit can be combined with each implementation of the light source.
  • the switch unit comprises: a first optical waveguide and a second optical waveguide, and at least one microring group corresponding to the at least one modulation unit; the outlet port of the switch unit is one end of the second optical waveguide; the first optical waveguide and the second optical waveguide are both strip-shaped and extend in the same direction; the microring group comprises: at least two switch microrings arranged in sequence and at intervals between the first optical waveguide and the second optical waveguide along the arrangement direction of the first optical waveguide and the second optical waveguide, and different switch microrings have different radii; the first optical waveguide couples the switch microring adjacent to the first optical waveguide in the microring group, and the second optical waveguide couples the switch microring adjacent to the second optical waveguide in the microring group.
  • the switch microrings are coupled to each other in the microring group; when the at least one microring group includes a plurality of microring groups, the plurality of microring groups are sequentially spaced and arranged along the extension direction of the first optical waveguide; for the wavelength group and the microring group corresponding to the one modulation unit: the first optical waveguide is used to receive the light of the wavelength group emitted by the light source; in a first time period, the control unit is used to control the microring group to couple the light of the first wavelength in the wavelength group transmitted in the first optical waveguide to the second optical waveguide and then output it; in a second time period, the control unit is used to control the microring group to couple the light of the second wavelength in the wavelength group transmitted in the first optical waveguide to the second optical waveguide and then output it.
  • the switch unit has multiple output ports, which is applicable to the case where the optical transmitter includes multiple modulation units.
  • the third implementation of the switch unit can be combined with each implementation of the light source.
  • the switch unit comprises: a first optical waveguide, a plurality of micro-ring groups corresponding to the plurality of modulation units one by one, and a plurality of third optical waveguides corresponding to the plurality of modulation units one by one; the outlet port corresponding to the modulation unit is one end of the third optical waveguide corresponding to the modulation unit; for the micro-ring group and the third optical waveguide corresponding to the one modulation unit: the first optical waveguide and the third optical waveguide are both in strip shape and have the same extension direction; the micro-ring group comprises: at least two switch micro-rings arranged in sequence and at intervals between the first optical waveguide and the third optical waveguide along the arrangement direction of the first optical waveguide and the third optical waveguide, and the radii of different switch micro-rings are different; the first optical waveguide couples the micro-rings in the micro-ring group that are opposite to the first optical waveguide the second optical waveguide is coupled to the switch microring adjacent to the second optical waveguide in the microring group, and the switch microring
  • the modulation unit may modulate the optical signal by in-phase orthogonal modulation, or may not modulate the optical signal by in-phase orthogonal modulation (such as direct modulation), and this application does not limit this.
  • the modulation unit is used to modulate light by in-phase orthogonal modulation. Furthermore, the first implementable manner is applicable to the case where the optical transmitter includes one or more modulation units and the switch unit has one output port. The first implementable manner of the modulation unit can be combined with the first implementable manner or the second implementable manner of the switch unit.
  • the optical transmitter further includes: a Mach-Zehnder interferometer (MZI) waveguide and a phase shifter;
  • MZI waveguide includes: a first waveguide arm and a second waveguide arm connected in parallel and of equal length;
  • the modulation unit includes: a first modulation microring and a second modulation microring; the radius of the first modulation microring is the same as the radius of the second modulation microring; the first modulation microring is spaced and coupled to the first waveguide arm, and the second modulation microring is spaced and coupled to the second waveguide arm; when the at least one modulation unit includes a plurality of modulation units, the plurality of modulation units are arranged along the first modulation microring.
  • MZI Mach-Zehnder interferometer
  • the extending direction of a waveguide arm is arranged in sequence at intervals; the phase shifter is located on the second waveguide arm and on the side of the at least one modulation unit away from the end of the MZI waveguide; for one modulation unit and its corresponding wavelength group: in a first time period, one end of the MZI waveguide is used to receive the light of the first wavelength in the wavelength group output by the switch unit; the first modulation microring is used to perform phase shift keying modulation on the light of the first wavelength in the first waveguide arm; the second modulation microring is used to perform phase shift keying modulation on the light of the first wavelength in the second waveguide arm; the phase shifter is used to perform 90 degree phase shift on the passing light.
  • one end of the MZI waveguide is used to receive the light of the second wavelength in the wavelength group output by the switch unit; the first modulation microring is used to perform phase shift keying modulation on the light of the second wavelength in the first waveguide arm; the second modulation microring is used to perform phase shift keying modulation on the light of the second wavelength in the second waveguide arm; the phase shifter is used to perform 90 degree phase shift on the passing light.
  • the modulation unit is also used to modulate the optical signal by in-phase orthogonal modulation.
  • the second implementation is applicable to the case where the optical transmitter includes a modulation unit and the switch unit has an output port.
  • the second implementation of the modulation unit can be combined with the first implementation or the second implementation of the switch unit.
  • the modulation unit includes: a first non-equal-arm Mach-Zehnder modulator (MZM), a second non-equal-arm MZM; the optical transmitter also includes an MZI waveguide and a phase shifter.
  • the MZI waveguide includes: a first waveguide arm and a second waveguide arm connected in parallel and of equal length; the first non-equal-arm MZM is located on the first waveguide arm, and the second non-equal-arm MZM is located on the second waveguide arm; the phase shifter is located on the second waveguide arm, and is located on the side of the second non-equal-arm MZM away from one end of the MZI waveguide.
  • one end of the MZI waveguide is used to receive the light of the first wavelength in the wavelength group corresponding to the modulation unit output by the switch unit; the first non-equal-arm MZM is used to perform phase shift keying modulation on the light of the first wavelength in the first waveguide arm; the second non-equal-arm MZM is used to perform phase shift keying modulation on the light of the first wavelength in the second waveguide arm; the phase shifter is used to perform 90-degree phase shift on the passing light.
  • one end of the MZI waveguide is used to receive the light of the second wavelength in the wavelength group corresponding to the modulation unit output by the switch unit; the first non-equal-arm MZM is used to perform phase shift keying modulation on the light of the second wavelength in the first waveguide arm; the second non-equal-arm MZM is used to perform phase shift keying modulation on the light of the second wavelength in the second waveguide arm; and the phase shifter is used to perform 90-degree phase shift on the passing light.
  • the modulation unit is used to modulate the optical signal by direct modulation, and the direct modulation has only intensity modulation and no phase modulation.
  • the third implementation is applicable to the case where the optical transmitter includes one or more modulation units and the switch unit has one output port.
  • the third implementation of the modulation unit can be combined with the first implementation or the second implementation of the switch unit.
  • the optical transmitter further includes: a fourth optical waveguide
  • the modulation unit includes: a modulation microring; the fourth optical waveguide is in a strip shape; the modulation microring is spaced and coupled with the fourth optical waveguide; when the at least one modulation unit includes multiple modulation units, the multiple modulation microrings in the multiple modulation units are arranged in sequence along the extension direction of the fourth optical waveguide; for the one modulation unit and its corresponding wavelength group: in a first time period, the fourth optical waveguide is used to receive the light of the first wavelength in the wavelength group output by the switch unit, and the modulation microring is used to modulate the light of the first wavelength on the fourth optical waveguide. In a second time period, the fourth optical waveguide is used to receive the light of the second wavelength in the wavelength group output by the switch unit, and the modulation microring is used to modulate the light of the second wavelength on the fourth optical waveguide.
  • the modulation unit is used to modulate the optical signal by direct modulation, and the fourth implementation is applicable to the case where the optical transmitter includes a modulation unit and the switch unit has an output port.
  • the fourth implementation of the modulation unit can be combined with the first implementation or the second implementation of the switch unit.
  • the modulation unit includes: a non-equal-arm MZM, the non-equal-arm MZM includes two waveguide arms connected in parallel and having different lengths, and the two ends of the two waveguide arms are connected respectively.
  • the modulation unit is used to modulate the optical signal by in-phase orthogonal modulation (or direct modulation), and the fifth implementation is applicable to the case where the optical transmitter includes multiple modulation units and the switch unit has one output port.
  • the fifth implementation of the modulation unit can be combined with the first implementation or the second implementation of the switch unit.
  • the at least one modulation unit includes multiple modulation units;
  • the optical transmitter also includes: a second DEMUX and a second MUX; for the one modulation unit and its corresponding wavelength group: in a first time period, the second DEMUX is used to receive the light of the first wavelength in the wavelength group and transmit the light of the first wavelength to the modulation unit; the modulation unit is used to modulate the light of the first wavelength; the second MUX is used to receive and output the optical signal modulated by the modulation unit.
  • the second DEMUX is used to receive the light of the second wavelength in the wavelength group and transmit the light of the second wavelength to the modulation unit; the modulation unit is used to modulate the light of the second wavelength; the second MUX is used to receive and output the optical signal modulated by the modulation unit.
  • the modulation unit is used to modulate the optical signal by in-phase orthogonal modulation (or direct modulation), and the sixth possible implementation is applicable to the case where the optical transmitter includes multiple modulation units and the switch unit has multiple output ports.
  • the sixth possible implementation of the modulation unit can be combined with the third possible implementation of the switch unit.
  • the optical transmitter also includes: a second MUX; for the one modulation unit and its corresponding wavelength group: in the first time period, the modulation unit is used to receive the light of the first wavelength in the wavelength group output by the corresponding output port in the switch unit, and modulate the light of the first wavelength; the second MUX is used to receive and output the optical signal modulated by the modulation unit.
  • the modulation unit is used to receive the light of the second wavelength in the wavelength group output by the corresponding output port in the switch unit, and modulate the light of the second wavelength;
  • the second MUX is used to receive and output the optical signal modulated by the modulation unit.
  • the present application also provides a light transmission method, which is performed by any optical transmitter provided in the first aspect.
  • the light transmission method includes: a light source provides light of multiple wavelengths to a switching unit, wherein the multiple wavelengths include a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit; within a first time period, a control unit controls the switching unit to output light of the first wavelength to the modulation unit, and the modulation unit modulates the input light of the first wavelength to output modulated light of the first wavelength; within a second time period, the control unit controls the switching unit to output light of the second wavelength to the modulation unit, and the modulation unit modulates the input light of the second wavelength to output modulated light of the second wavelength.
  • the difference between the first wavelength and the second wavelength is FSR.
  • the optical transmitter includes: a plurality of modulation units; the plurality of wavelengths of light emitted by the light source include: a plurality of wavelength groups corresponding to the plurality of modulation units one by one; for a wavelength group corresponding to a modulation unit, the wavelength group includes a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit; the first wavelengths in different wavelength groups are different, and the second wavelengths in different wavelength groups are different.
  • control unit In a first time period, the control unit can control the switch unit to output light of the first wavelength in the corresponding wavelength group to the modulation unit; in a second time period, the control unit can control the switch unit to output light of the second wavelength in the corresponding wavelength group to the modulation unit.
  • the light emission method provided in the embodiment of the present application is related to the implementable manner of the switch unit.
  • the switch unit adopts the implementable method described in (2.1) above, taking a modulation unit as an example, the light source provides the light of the wavelength group corresponding to the modulation unit to the first DEMUX.
  • the control unit controls the optical switch group to transmit the light of the first wavelength in the wavelength group to the first MUX and then to the modulation unit; in the second time period, the control unit controls the optical switch group to transmit the light of the second wavelength in the wavelength group to the first MUX and then to the modulation unit.
  • the light source provides the light of the wavelength group corresponding to the modulation unit to the first optical waveguide.
  • the control unit controls the micro-ring group to couple the light of the first wavelength transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit; in the second time period, the control unit controls the micro-ring group to couple the light of the second wavelength transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit.
  • the light source provides light of multiple wavelengths to the first optical waveguide.
  • the control unit can control the micro-ring group to couple the light of the first wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it, and in the second time period, the control unit can control the micro-ring group to couple the light of the second wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it.
  • a switch control method which can be executed by a control unit in any optical transmitter provided in the first aspect, and the method comprises: in a first time period, the control unit controls the switch unit to output a light of a first wavelength among a plurality of wavelengths provided by a light source to a modulation unit, so that the modulation unit modulates the input light of the first wavelength to output modulated light of the first wavelength; in a second time period, the control unit controls the switch unit to output a light of a second wavelength among a plurality of wavelengths provided by the light source to the modulation unit, so that the modulation unit modulates the input light of the second wavelength to output modulated light of the second wavelength.
  • the plurality of wavelengths include a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit.
  • a switch control device which belongs to the control unit in the optical transmitter described in any design in the first aspect, and the switch control device includes various modules for executing the control method provided in the third aspect.
  • a switch control device comprising: a processor and a memory, wherein a program is stored in the memory, and the processor is used to execute the program stored in the memory to implement the method described in the third aspect.
  • a chip in a sixth aspect, includes a programmable logic circuit and/or program instructions, and when the chip is running, it is used to implement the method described in the third aspect.
  • a computer-readable storage medium wherein instructions are stored in the computer-readable storage medium.
  • the computer executes the method described in the third aspect.
  • a computer program product comprising instructions is provided, and when the computer program product is run on a computer, the computer is caused to execute the method described in the third aspect.
  • an optical module comprising an optical transmitter as described in any design of the first aspect, and an optical receiver.
  • an optical communication device comprising the optical module described in the ninth aspect, and a processing circuit; the processing circuit is used to provide a driving signal carrying data to be transmitted to the optical module, and the modulation unit in the optical module is used to modulate light based on the driving signal.
  • an optical communication system comprising a plurality of the optical communication devices according to the tenth aspect.
  • FIG1 is a schematic diagram of the structure of an optical communication system provided in an embodiment of the present application.
  • FIG2 is a schematic diagram of the structure of another optical communication system provided in an embodiment of the present application.
  • FIG3 is a schematic diagram of the structure of an optical transmitter provided in an embodiment of the present application.
  • FIG4 is a schematic diagram of the structure of another optical transmitter provided in an embodiment of the present application.
  • FIG5 is a schematic diagram of the structure of another optical transmitter provided in an embodiment of the present application.
  • FIG6 is a schematic diagram of a communication network provided in an embodiment of the present application.
  • FIG7 is a schematic diagram of an optical communication system provided in an embodiment of the present application.
  • FIG8 is a schematic diagram of the structure of an optical transmitter provided in an embodiment of the present application.
  • FIG9 is a schematic diagram of the power of light emitted by a light source provided in an embodiment of the present application.
  • FIG10 is a schematic diagram of filtering of a first wavelength provided in an embodiment of the present application.
  • FIG11 is a schematic diagram of filtering of a second wavelength provided in an embodiment of the present application.
  • FIG12 is a schematic diagram of a spectrum of an MRM provided in an embodiment of the present application.
  • FIG13 is a schematic diagram of a spectrum of a non-equal-arm MZM provided in an embodiment of the present application.
  • FIG14 is a schematic diagram of the structure of a switch unit provided in an embodiment of the present application.
  • FIG15 is a schematic diagram of the structure of another switch unit provided in an embodiment of the present application.
  • FIG16 is a schematic diagram of the structure of another switch unit provided in an embodiment of the present application.
  • FIG17 is a schematic diagram of the structure of another switch unit provided in an embodiment of the present application.
  • FIG18 is a schematic diagram of the structure of another switch unit provided in an embodiment of the present application.
  • FIG19 is a schematic diagram of the structure of a modulation unit provided in an embodiment of the present application.
  • FIG20 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG21 is a constellation diagram of a signal provided in an embodiment of the present application.
  • FIG22 is a constellation diagram of another signal provided in an embodiment of the present application.
  • FIG23 is a constellation diagram of another signal provided in an embodiment of the present application.
  • FIG24 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG25 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG26 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG27 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG28 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG29 is a schematic diagram of the structure of another modulation unit provided in an embodiment of the present application.
  • FIG30 is a flow chart of a light emission method provided in an embodiment of the present application.
  • FIG31 is a flow chart of a switch control method provided in an embodiment of the present application.
  • FIG32 is a schematic diagram of the structure of a switch control device provided in an embodiment of the present application.
  • the embodiment of the present application provides an optical communication system, which includes a plurality of optical communication devices. There are links between the optical communication devices, and the optical communication devices can communicate with each other through optical signals transmitted on the links.
  • Optical communication equipment can be any device that communicates through optical signals, such as optical line terminal (OLT), optical transport network (OTN) equipment, data center, etc.
  • OLT optical line terminal
  • OTN optical transport network
  • the link for transmitting optical signals may include an optical fiber, and the link may also include one or more devices arranged on the optical fiber, such as an optical power amplifier (booster amplifier, BA), an optical line amplifier (optical line amplifier, OLA), and a pre-amplifier (pre-amplifier, PA).
  • Some link segments in the link may also detect parameters such as wavelength and optical power of the optical signal by setting an optical supervisory channel (optical supervisory channel, OSC).
  • FIG1 is a schematic diagram of the structure of an optical communication system provided in an embodiment of the present application.
  • FIG1 shows a first optical communication device 01 and a second optical communication device 02, and a link between the first optical communication device 01 and the second optical communication device 02.
  • the link includes an optical fiber 03, and BA 04, OLA 05, and PA 06 arranged on the optical fiber 03 and arranged in sequence from the first optical communication device 01 to the second optical communication device 01, and OSC is set in some link segments.
  • the optical communication device includes an optical module, and the optical module includes an optical transmitter (transmitter, Tx) and an optical receiver (receiver, Rx).
  • the optical transmitter is used to modulate the optical signal to be transmitted by the optical communication device
  • the optical receiver is used to demodulate the optical signal received by the optical communication device.
  • the optical communication device 01 sends an optical signal to the optical communication device 02 as an example.
  • the optical module in the first optical communication device 01 (not shown in Figure 1) includes an optical transmitter 011
  • the optical module in the second optical communication device 02 includes an optical receiver 021.
  • the optical transmitter 011 can modulate the optical signal and transmit the optical signal to the optical receiver 021 of the second optical communication device 02 through a link.
  • the optical receiver 021 in the second optical communication device 02 can demodulate the optical signal.
  • the optical communication equipment may also include other structures.
  • the optical communication equipment also includes a processing circuit; the processing circuit is used to provide a driving signal carrying the data to be transmitted to the optical module, and the modulation unit in the optical module is used to modulate the light based on the driving signal to obtain an optical signal.
  • the number of optical transmitters in optical communication equipment can also be multiple, and the number of optical receivers in optical communication equipment can also be multiple.
  • the optical communication system can be based on a wavelength division multiplexing (WDM) system, such as a dense wavelength division multiplexing (DWDM) system.
  • WDM wavelength division multiplexing
  • DWDM dense wavelength division multiplexing
  • the optical module in the first optical communication device 01 includes three optical transmitters 011 and MUX
  • the optical module in the second optical communication device 02 includes three optical receivers 021 and DEMUX.
  • Each optical transmitter 011 in the first optical communication device 01 is connected to the link through MUX
  • each second optical receiver 021 in the second optical communication device 02 is connected to the link through DEMUX.
  • the optical transmitter 011 is used to emit an optical signal of a wavelength, and the wavelengths of the optical signals emitted by different optical transmitters 011 are different
  • different optical receivers 021 are used to receive an optical signal of a wavelength, and the wavelengths of the optical signals received by different optical receivers 021 are also different.
  • optical transmitter may be implemented in a variety of ways.
  • the optical transmitter may include a light source 0111 and a modulation unit 0112.
  • the light source 0111 is used to provide light of one wavelength
  • the modulation unit 0112 is used to modulate the light to obtain an optical signal of the one wavelength.
  • the optical transmitter may include a light source 0111, a modulation unit 0112, and an optical transponder unit (OTU) 0113.
  • the light source 0111 is used to provide light of one wavelength;
  • the modulation unit 0112 is used to modulate the light to obtain an optical signal of the one wavelength;
  • the OTU 0113 is used to convert the wavelength of the optical signal to obtain an optical signal of another wavelength.
  • OTU can also be implemented in multiple ways.
  • OTU 0113 includes a pump light source 01131A and a nonlinear device 01132A.
  • Nonlinear device 01132A includes nonlinear materials (such as silicon nitride, lithium niobate, etc.), and nonlinear device 01132A can be a silicon nitride microring, a thin film lithium niobate waveguide, etc.
  • the pump light source 01131A is used to provide pump laser to the nonlinear device 01132A, and the optical signal of one wavelength modulated by the modulation unit 0112 will be transmitted to the nonlinear device 01132A.
  • the optical signal of one wavelength can be converted into an optical signal of another wavelength in the nonlinear device 01132A, realizing the wavelength conversion of the optical signal.
  • the conversion efficiency of the optical signal in the nonlinear device 01132A is low, and the power of the converted optical signal is small, which affects the quality of the optical signal.
  • the optical signal will introduce noise in the process of passing through the nonlinear device, resulting in degradation of the optical signal, with OSNR cost, affecting the communication effect.
  • OTU 0113 uses an optoelectronic method to switch the wavelength of the optical signal.
  • OTU 0113 includes a photodiode (PD) 01131B and a direct-modulation optical module 01132B.
  • PD photodiode
  • the direct-modulation optical module 01132B includes another light source and another modulation unit (not shown in FIG5 ).
  • the light source of the direct-modulation optical module 01132B provides light of a different wavelength from the light source 0111.
  • the modulation unit in the direct-modulation optical module 01132B can modulate the electrical signal to obtain an optical signal of another wavelength, thereby realizing the wavelength conversion of the optical signal.
  • PD 01131B can only demodulate the power of the optical signal but cannot demodulate the phase of the optical signal, PD 01131B can only convert the directly modulated optical signal into an electrical signal, but cannot convert the co-directional orthogonal optical signal (coherent optical signal) into an electrical signal. Therefore, the optical transmitter where OTU 0113 shown in Figure 5 is located cannot output co-directional orthogonal optical signals.
  • the optical transmitter when the optical transmitter needs to output optical signals of multiple wavelengths (as shown in Figure 2), the optical transmitter needs to include multiple light sources, multiple modulation units, multiple PDs and multiple direct modulation optical modules. It can be seen that the number of devices in the optical transmitter is large, and the cost and power consumption of the optical transmitter are high.
  • the modulation method of the direct modulation optical module is relatively complex (for example, four-level pulse amplitude modulation is used), the performance requirements of each device in the optical transmitter are relatively high.
  • the PD needs to have a better response coefficient and sensitivity, and the modulation unit needs to have a higher extinction ratio and linearity, otherwise there will be problems of introducing noise or losing information carried by the optical signal.
  • optical communication equipment may switch the wavelength of an optical signal to be transmitted.
  • the communication network between the first optical communication device 01 and the second optical communication device 02 is as shown in FIG6 , there may be a link A (node 1 ⁇ node 2 ⁇ node 3 ⁇ node 7) and a link B (node 1 ⁇ node 4 ⁇ node 7) between the first optical communication device 01 and the second optical communication device 02.
  • link A node 1 ⁇ node 2 ⁇ node 3 ⁇ node 7
  • link B node 1 ⁇ node 4 ⁇ node 7
  • the first optical communication device 01 In link B, if the wavelength 1 of the optical signal originally sent by the first optical communication device 01 is already occupied, the first optical communication device 01 also needs to switch the wavelength of the optical signal, for example, the first optical communication device 01 switches the wavelength 1 of the original optical signal to the unoccupied wavelength 2.
  • the optical communication system includes 8 optical communication devices A to H, wherein the optical communication device A can send optical signals to the optical communication devices E and F, the optical communication device B can send optical signals to the optical communication device G, the optical communication device C can send optical signals to the optical communication devices G and H, and the optical communication device D can send optical signals to the optical communication device H.
  • the optical communication devices E to H can process the received optical signals.
  • the optical communication device C is the first optical communication device
  • the optical communication device C when the optical communication device C is sending an optical signal to the optical communication device G, if the load of the optical communication device G is high and the load of the optical communication device H is low, the optical communication device C can stop sending the optical signal to the optical communication device G and switch to sending the optical signal to the optical communication device H. If the wavelength of the optical signal sent by the optical communication device C is the same as the wavelength of the optical signal sent by the optical communication device D to the optical communication device H, the optical communication device C needs to switch the wavelength of the optical signal sent to the optical communication device H.
  • Optical communication equipment uses an optical transmitter to switch the wavelength of an optical signal.
  • the process of switching the wavelength of an optical signal by an optical transmitter is complicated and slow.
  • the light source 0111 in the optical transmitter switches the wavelength of the light provided to the modulation unit 0112.
  • the modulation unit 0112 modulates the light to obtain the optical signal
  • the bias voltage and the electrical signal carrying the data also called the driving signal, which can be provided by the processing circuit in the optical communication device
  • the modulation effect of the modulation unit 0112 on the light of the same wavelength is different under different bias voltages. Therefore, after the light source 0111 switches the wavelength of the light, in order to achieve effective modulation of the light, the optical transmitter also needs to adjust the bias voltage of the modulation unit 0112 according to the wavelength of the switched light.
  • the light source 0111 it takes several seconds for the light source 0111 to switch the wavelength of the light, and it takes more than ten seconds or tens of seconds for the optical transmitter to adjust the bias voltage of the modulation unit 0112. In this way, it takes more than ten seconds or tens of seconds for the optical transmitter to switch the wavelength of the optical signal.
  • the time for the optical transmitter to switch the wavelength of the optical signal to be transmitted must be controlled within 50 milliseconds. It can be seen that the optical transmitter shown in FIG3 cannot meet this requirement, which will cause a long period of service interruption and affect the stability and continuity of communication.
  • the pump light source 01131A in the optical transmitter switches the wavelength of the pump laser so that the wavelength of the optical signal output by the nonlinear device 01132A in the optical transmitter changes.
  • the pump light source 01131A needs several seconds to switch the wavelength of the optical signal.
  • the time for the optical transmitter to switch the wavelength of the optical signal must be controlled within 50 milliseconds. It can be seen that the optical transmitter shown in FIG4 cannot meet this requirement, which will cause a long interruption of the service and affect the stability and continuity of communication.
  • the light source in the direct-modulation optical module 01132B in the optical transmitter switches the wavelength of the light provided to the modulation unit in the direct-modulation optical module 01132B.
  • the optical transmitter also needs to adjust the bias voltage of the modulation unit in the direct-modulation optical module 01132B according to the wavelength. However, it takes several seconds for the light source in the direct-modulation optical module 01132B to switch the wavelength of the light, and it takes more than ten seconds or tens of seconds for the optical transmitter to adjust the bias voltage of the modulation unit in the direct-modulation optical module 01132B.
  • the optical transmitter In this way, it takes more than ten seconds or tens of seconds for the optical transmitter to switch the wavelength of the optical signal to be sent. In order to ensure the stability of communication, the time for the optical transmitter to switch the wavelength of the optical signal to be sent must be controlled within 50 milliseconds. It can be seen that the optical transmitter shown in FIG5 cannot meet this requirement, which will cause a long interruption of the service and affect the stability and continuity of communication.
  • the embodiment of the present application provides an optical transmitter, which has a relatively simple process of switching the wavelength of an optical signal and a relatively fast speed of switching the wavelength of an optical signal, and can control the time of switching the wavelength of an optical signal to be within 50 milliseconds.
  • the optical transmitter provided in the embodiment of the present application can also modulate to obtain orthogonal optical signals in the same direction.
  • FIG8 is a schematic diagram of the structure of an optical transmitter provided in an embodiment of the present application.
  • the optical transmitter includes: a light source 101, a switch unit 102, a modulation unit 103 and a control unit 104.
  • the light source 101, the switch unit 102 and the modulation unit 103 are connected in sequence, and the control unit 104 is connected to the switch unit 102.
  • the light source 101 is used to provide a plurality of wavelengths of light (also called continuous light) to the switch unit 102.
  • the plurality of wavelengths may be wavelengths matching the International Telecommunication Union (ITU) standard, such as wavelengths matching the ITU DWDM standard.
  • the plurality of wavelengths include a first wavelength and a second wavelength, the difference between the first wavelength and the second wavelength being an integer multiple of the FSR of the modulation unit, and the absolute value of the difference between the first wavelength and the second wavelength being a positive integer multiple of the FSR of the modulation unit.
  • the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit.
  • the control unit 104 is used to control the switch unit 102 to output light of a first wavelength to the modulation unit 103 in a first time period, and to control the switch unit 102 to output light of a second wavelength to the modulation unit 103 in a second time period.
  • the modulation unit 103 is used to modulate the first wavelength light input by the switch unit 102 in a first time period to output modulated light of the first wavelength, and to modulate the second wavelength light input by the switch unit 102 in a second time period to output modulated light of the second wavelength.
  • the spectrum response of the modulation unit 103 at any two wavelengths whose wavelength difference is an integer multiple of the FSR is the same (or approximately the same). Since the difference between the first wavelength and the second wavelength among the multiple wavelengths is an integer multiple of the FSR of the modulation unit, the modulation unit 103 has the same (or approximately the same) modulation effect on the light of the first wavelength and the second wavelength. For example, the extinction ratio, bandwidth, bit error rate and other performances modulated by the modulation unit at the first wavelength and the second wavelength are consistent.
  • the wavelength of the light input to the modulation unit 103 by the switch unit 102 can be switched between the first wavelength and the second wavelength, but the modulation effect of the modulation unit 103 on the light before and after the wavelength switching is the same (or approximately the same), so there is no need to change the bias voltage loaded on the modulation unit 103.
  • the driving signal loaded on the modulation unit 103 is related to the business.
  • the data carried by the driving signal remains unchanged, and the driving signal loaded on the modulation unit 103 remains unchanged;
  • the business changes the data carried by the driving signal changes, and the driving signal loaded on the modulation unit 103 also changes.
  • the light source can provide light of multiple wavelengths to the switch unit, and the control unit can control the switch unit to output light of the first wavelength or the second wavelength among the multiple wavelengths to the modulation unit, so that the modulation unit can modulate the received light. Since the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit, and the wavelength of the light input to the modulation unit by the switch unit can be switched between the first wavelength and the second wavelength, when the optical transmitter needs to switch the wavelength of the optical signal between the first wavelength and the second wavelength, the modulation unit does not need to change the bias voltage, and the light source does not need to change the light provided.
  • the control unit only needs to control the switch unit to output the light of the switched wavelength. It can be seen that the process of switching the wavelength of the optical signal of the optical transmitter is relatively simple.
  • the control unit controls the switch unit to switch the wavelength of the output light at a faster speed. Therefore, the optical transmitter switches the wavelength of the optical signal at a faster speed, and the optical communication equipment where the optical transmitter is located switches the wavelength of the emitted optical signal at a faster speed.
  • the time for the optical transmitter provided in the present application to switch the wavelength of the optical signal can be controlled within 50 milliseconds, which can achieve "seamless connection" of the service without affecting the continuity and consistency of the service.
  • the time required for the optical transmitter to switch the wavelength of the optical signal is in the millisecond level
  • the above-mentioned switch unit is a switch unit based on the electro-optical effect (which can be called an electro-optical switch)
  • the time required for the optical transmitter to switch the wavelength of the optical signal is in the nanosecond level.
  • the optical transmitter includes one modulation unit 103 as an example. It can be understood that the optical transmitter can also include multiple modulation units 103; the FSRs of different modulation units 103 can be the same or different.
  • the multiple wavelengths include: multiple wavelength groups corresponding to the multiple modulation units 103. For a wavelength group corresponding to a modulation unit 103, the wavelength group includes a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit 103. Different wavelength groups can be the same or different, the first wavelengths in different wavelength groups are different, and the second wavelengths in different wavelength groups are different.
  • control unit 104 is used to: control the switch unit 102 to output the first wavelength of the corresponding wavelength group to the modulation unit 103 in the first time period, and control the switch unit 102 to output the second wavelength of the corresponding wavelength group to the modulation unit 103 in the second time period.
  • the embodiment of the present application does not limit the size relationship of the wavelengths in the above-mentioned multiple wavelength groups.
  • the multiple wavelength groups can be arranged in order from small to large, in which case there is a situation where the minimum wavelength in one wavelength group is greater than the maximum wavelength in another wavelength group.
  • there may be an intersection among the multiple wavelength groups in which case there is a situation where some wavelengths in one wavelength group are greater than some wavelengths in another wavelength group, but less than other wavelengths in the other wavelength group.
  • the optical transmitter provided in the embodiment of the present application includes: a light source 101, a switch unit 102, at least one modulation unit 103 and a control unit 104.
  • the light source 101 is used to provide the switch unit 102 with light of at least one wavelength group corresponding to at least one modulation unit 103, wherein each wavelength group includes a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit 103 corresponding to the wavelength group.
  • the control unit 104 is used to control the switch unit 102 to output the light of the first wavelength in the wavelength group corresponding to the modulation unit 103 to each modulation unit 103 in a first time period, and to control the switch unit 102 to output the light of the second wavelength in the wavelength group corresponding to the modulation unit 103 to each modulation unit 103 in a second time period.
  • Each modulation unit 103 is used to modulate the light of the first wavelength in the wavelength group corresponding to the modulation unit 103 input by the switch unit 102 in the first time period to output the modulated light of the first wavelength.
  • Each modulation unit 103 is further configured to modulate the light of the second wavelength in the wavelength group corresponding to the modulation unit 103 input by the switch unit 102 within the second time period, so as to output modulated light of the second wavelength.
  • each wavelength group may not include other wavelengths, or may include other wavelengths, which is not limited in the embodiments of the present application.
  • the difference between any two wavelengths in the wavelength group can be an integer multiple of the FSR of the modulation unit corresponding to the wavelength group.
  • the difference between the i-th wavelength and the i+1-th wavelength arranged in order from small to large in the wavelength group is FSR, i ⁇ 1, in other words, the wavelengths in the wavelength group are arranged in sequence according to the intervals of FSR.
  • the 5 wavelengths are X, X+FSR, X+2*FSR, X+3*FSR and X+4*FSR respectively.
  • the wavelength of the optical signal is switched between the first wavelength and the second wavelength, and the wavelength of the optical signal is switched only once. It can be understood that when the wavelength group also includes other wavelengths in addition to the first wavelength and the second wavelength, the wavelength of the optical signal can be switched between any two wavelengths in the wavelength group, and the wavelength of the optical signal can be switched multiple times in the wavelength group.
  • the switch unit 102 can be regarded as a filter.
  • the filter interval of the switch unit 102 for the light of the wavelength group corresponding to each modulation unit 103 is larger than the wavelength range of the wavelength group, so that the switch unit 102 can select a wavelength of light from the light of the wavelength group and output it to the modulation unit corresponding to the wavelength group.
  • a wavelength group includes ⁇ 1 to ⁇ n, and n is greater than 1
  • the power of the light of these wavelengths output by the light source 101 can be shown in FIG9. It can be seen that the power of the light of these wavelengths is the same (or similar) and is greater than zero.
  • the switch unit 102 can make the filter response of the first wavelength ⁇ a in the wavelength group "1" under the control of the control electrical signal (voltage signal or current signal) provided by the control unit 104, so that the power of the light of the first wavelength ⁇ a output by the switch unit 102 is greater than zero, and then the modulation unit 103 corresponding to the wavelength group can modulate the light of the first wavelength ⁇ a to output the optical signal of the first wavelength ⁇ a.
  • the control electrical signal voltage signal or current signal
  • the switch unit 102 can also make the filter response of other wavelengths in the wavelength group except the first wavelength ⁇ a "0" under the control of the control electrical signal provided by the control unit 104, so that the power of the light of the other wavelengths output by the switch unit 102 is zero.
  • the wavelength of the optical signal When the wavelength of the optical signal is switched between the wavelengths in the wavelength group, it is only necessary to change the control electrical signal provided by the control unit 104 to the switch unit 102. For example, as shown in FIG11, assuming that in the second time period, the wavelength of the optical signal needs to be switched from the first wavelength ⁇ a in ⁇ 1 to ⁇ n in FIG10 to the second wavelength ⁇ b, then the control electrical signal provided by the control unit 104 to the switch unit 102 in the second time period is changed relative to the control electrical signal provided by the control unit 104 to the switch unit 102 in the first time period.
  • the switch unit 102 can, under the control of the control electrical signal provided by the control unit 104, make the filter response of the second wavelength ⁇ b in the wavelength group "1", so that the power of the light of the second wavelength ⁇ b output by the switch unit 102 is greater than zero, and then the modulation unit 103 corresponding to the wavelength group can modulate the light of the second wavelength ⁇ b to output the optical signal of the second wavelength ⁇ b.
  • the switch unit 102 can also, under the control of the control electrical signal provided by the control unit 104, make the filter response of other wavelengths in the wavelength group except the second wavelength ⁇ b "0", so that the power of the light of the other wavelengths output by the switch unit 102 is zero.
  • the modulation unit 103 is a modulator with FSR.
  • the modulation unit 103 can be a resonant modulator (such as a micro-ring modulator (MRM)) or an interferometric modulator (such as a non-equal-arm MZM), a Michelson interferometric modulator (MIM), etc.
  • MRM micro-ring modulator
  • MIM Michelson interferometric modulator
  • the FSR of the modulation unit 103 is the wavelength difference between two adjacent responses in the spectrum of the modulation unit 103 .
  • the difference between two adjacent resonant wavelengths of the resonant modulator is the FSR of the resonant modulator.
  • the resonant modulator as an MRM as an example, assuming that the MRM is used to modulate light in the C band (1529.16 nm to 1568.36 nm, 191.15 THz to 196.05 THz), and the MRM includes a silicon optical waveguide with a radius of 100 microns, the spectrum of the MRM is shown in FIG12, and the MRM has a total of 6 resonant wavelengths, namely 1543.181 nm, 1544.681 nm, 1546.183 nm, 1547.688 nm, 1549.197 nm, and 1550.708 nm, then the FSR of the MRM is approximately 1.505 nm.
  • the difference between two adjacent interference destructive wavelengths or the difference between two adjacent interference long wavelengths of the interference type resonator is the FSR of the interference type resonator.
  • the interference type resonator as a non-equal arm MZM as an example, assuming that the non-equal arm MZM is used to modulate light in the C band, and the non-equal arm MZM includes two waveguide arms, both of which include silicon optical waveguides, and the length difference between the two waveguide arms is 128 microns.
  • the spectrum of the non-equal arm MZM is shown in Figure 13.
  • the non-equal arm MZM has a total of 3 interference destructive wavelengths, which are 1545.32 nanometers, 1550.14 nanometers, and 1554.98 nanometers, respectively.
  • the FSR of the non-equal arm MZM is about 4.83 nanometers.
  • the FSR of the modulation unit is related to the geometric parameters of the modulation unit.
  • the FSR of the modulation unit ⁇ 2 /(2 ⁇ R ⁇ ng ), where ⁇ is any wavelength (such as the center wavelength) in the wavelength group corresponding to the modulation unit, ⁇ represents pi, R is the radius of the microring in the MRM, and ng is the group refractive index of the waveguide in the microring of the MRM.
  • the FSR of the modulation unit ⁇ 2 /( ⁇ L ⁇ ng ), where ⁇ L is the length difference between the two waveguide arms of the non-equal-arm MZM or non-equal-arm MIM.
  • the wavelength group corresponding to the modulation unit can be set as needed, and the wavelength of the light emitted by the light source, the geometric parameters of the switch unit and the geometric parameters of the modulation unit can be designed accordingly, so that the FSR of the modulation unit matches the wavelength of the light emitted by the light source (the difference between the wavelengths of any two wavelengths of light in the wavelength group corresponding to each modulation unit emitted by the light source is an integer multiple of the FSR of the modulation unit).
  • the optical transmitter provided in the embodiment of the present application is highly flexible and can be adapted to various communication standards.
  • optical transmitter including one modulation unit and an optical transmitter including multiple modulation units as examples for explanation.
  • the optical transmitter includes a modulation unit 103.
  • the light source 101 in the optical transmitter is used to output light of the wavelength group (including wavelengths 1 to 20) corresponding to the modulation unit 103. If in the first time period, wavelength 5 among wavelengths 1 to 20 is the first wavelength, then the switch unit 102 can output the light of wavelength 5 to the modulation unit 103 under the control of the control unit 104, and prohibit the output of light of wavelengths 1-4 and wavelengths 6-20.
  • the modulation unit 103 modulates the light of wavelength 5 so that the optical transmitter outputs an optical signal of wavelength 5.
  • wavelength 7 among wavelengths 1 to 20 is the second wavelength
  • the switch unit 102 can output the light of wavelength 7 to the modulation unit 103 under the control of the control unit 104, and prohibit the output of light of wavelengths 1-6 and wavelengths 8-20.
  • the modulation unit 103 modulates the light of wavelength 7 so that the optical transmitter outputs an optical signal of wavelength 7. In this way, the wavelength of the optical signal output by the optical transmitter is switched from wavelength 5 to wavelength 7.
  • the light source 101 continues to emit light of multiple wavelengths, and the bias voltage loaded on the modulation unit 103 does not need to be changed.
  • the optical transmitter includes four modulation units 103.
  • the light source 101 in the optical transmitter is used to output light with wavelengths 1 to 50, wherein the wavelength group corresponding to the first modulation unit 103 includes: wavelengths 1, 5...49; the wavelength group corresponding to the second modulation unit 103 includes: wavelengths 2, 6...50; the wavelength group corresponding to the third modulation unit 103 includes: wavelengths 3, 7...47; the wavelength group corresponding to the fourth modulation unit 103 includes: wavelengths 4, 8...48.
  • wavelength 5 in wavelengths 1, 5...49 is the first wavelength
  • wavelength 6 in wavelengths 2, 6...50 is the first wavelength
  • wavelength 7 in wavelengths 3, 7...47 is the first wavelength
  • wavelength 8 in wavelengths 4, 8...48 is the first wavelength.
  • the switch unit 102 can output light with wavelengths 5, 6, 7, and 8, and prohibit the output of light with wavelengths 1-4 and light with wavelengths 9-50.
  • the first modulation unit 103 can modulate the light of wavelength 5, the second modulation unit 103 can modulate the light of wavelength 6, the third modulation unit 103 can modulate the light of wavelength 7, and the fourth modulation unit 103 can modulate the light of wavelength 8, so that the optical transmitter outputs optical signals of wavelengths 5, 6, 7, and 8.
  • the switch unit 102 can switch the wavelength of the output light from the first wavelength to the second wavelength under the control of the control unit 104, so that the modulation unit 103 modulates the light of the second wavelength.
  • the light source 101 continuously emits light of multiple wavelengths, and the bias voltage loaded on the modulation unit 103 does not need to be changed.
  • the number of wavelengths in the wavelength groups corresponding to different modulation units 103 may be the same or different.
  • the wavelengths in the wavelength groups corresponding to one or more modulation units 103 may be switched.
  • the wavelength difference of the wavelengths of the optical signals modulated by different modulation units 103 before and after the switching may be the same or different, which is not limited in the embodiments of the present application.
  • the modulation speed of the optical transmitter is the sum of the modulation speeds of the multiple modulation units 103. For example, assuming that the modulation speed of each modulation unit 103 is 100 Gbits per second (Gb/s), and the optical transmitter includes four modulation units 103, the modulation speed of the optical transmitter is 400 Gbits per second.
  • the light source 101, the switch unit 102 and the modulation unit 103 may be implemented in a variety of ways. The following will introduce the various ways of implementing each part of the light source 101, the switch unit 102 and the modulation unit 103 respectively.
  • the light source 101 may include a QDMLL or a QWMLL.
  • both the QDMLL and the QWMLL may emit 50 wavelengths of light in the range of 1540 nm to 1560 nm, and the interval between adjacent wavelengths in the 50 wavelengths is 0.4 nm, and the interval between the frequencies corresponding to the adjacent wavelengths is 50 GHz, and these wavelengths may match the ITU, such as the ITU DWDM standard.
  • the light source 101 may be an optical frequency comb.
  • the optical frequency comb can emit light of multiple wavelengths with different repetition rates within a certain wavelength range (for example, frequency intervals of 50 GHz, 100 GHz, etc.).
  • the light source 101 may be a light source pool.
  • the light source pool includes a plurality of lasers corresponding to the plurality of wavelengths, and a MUX, each laser being used to emit light of a corresponding wavelength, and the MUX being used to combine the light of the plurality of wavelengths emitted by the plurality of lasers.
  • the switch unit 102 may have an output port, and the switch unit 102 is used to output light from the output port to each modulation unit 103. For example, in a first time period, the switch unit 102 is used to output light of a first wavelength in a wavelength group corresponding to the modulation unit 103 from the output port to each modulation unit 103. In a second time period, the switch unit 102 is used to output light of a second wavelength in a wavelength group corresponding to the modulation unit 103 from the output port to each modulation unit 103. This situation is applicable to the case where the optical transmitter includes one or more modulation units 103.
  • the switch unit 102 has a plurality of output ports corresponding to the plurality of modulation units 103, and the switch unit 102 is used to output light to the modulation unit from the output ports corresponding to the modulation unit 103.
  • the switch unit 102 is used to output light of a first wavelength in a wavelength group corresponding to the modulation unit 103 from the output port corresponding to the modulation unit 103 to the modulation unit 103.
  • the switch unit 102 is used to output light of a second wavelength in a wavelength group corresponding to the modulation unit 103 from the output port corresponding to the modulation unit 103 to the modulation unit 103.
  • the switch unit 102 has one output port, which is applicable to the case where the optical transmitter includes one or more modulation units 103.
  • the first implementation of the switch unit 102 can be combined with each implementation of the light source 101.
  • the switch unit 102 includes: a first DEMUX and a first MUX, and an optical switch group corresponding to the modulation unit 103.
  • the optical transmitter includes at least one modulation unit 103, and therefore, the switch unit 102 includes at least one optical switch group corresponding to the at least one modulation unit 103.
  • FIG14 only shows one optical switch group corresponding to one modulation unit 103.
  • the switch unit 102 includes multiple optical switch groups (for example, when the optical transmitter includes two modulation units 103, the switch unit 102 in FIG15 includes two optical switch groups).
  • One output port of the switch unit 102 is the output port of the first MUX.
  • the first DEMUX is used to receive the light of the wavelength group;
  • the optical switch group includes: a plurality of optical switches corresponding to each wavelength in the wavelength group; the plurality of optical switches may be the same or different.
  • the first DEMUX is used to transmit the received light of each wavelength in the wavelength group to the optical switches corresponding to each wavelength.
  • the control unit (not shown in FIG. 14 and FIG.
  • the optical switch corresponding to the first wavelength in the optical switch group is used to control the optical switch corresponding to the first wavelength in the optical switch group to turn on, and control the optical switch not corresponding to the first wavelength in the optical switch group to turn off; in this way, the light of the first wavelength in the wavelength group is transmitted to the first MUX and then output to the modulation unit 103, while the light of other wavelengths in the wavelength group except the first wavelength cannot be transmitted to the first MUX and output to the modulation unit 103.
  • the control unit (not shown in Figures 14 and 15) is used to control the optical switch corresponding to the second wavelength in the optical switch group to be turned on, and control the optical switch in the optical switch group that does not correspond to the second wavelength to be turned off; in this way, the light of the second wavelength in the wavelength group is transmitted to the first MUX and then output to the modulation unit 103, while the light of other wavelengths in the wavelength group except the second wavelength cannot be transmitted to the first MUX and output to the modulation unit 103.
  • the first DEMUX is used to receive the light of the wavelength group corresponding to each modulation unit in the at least one modulation unit 103; the first DEMUX is used to transmit the received light of these wavelengths to the optical switches corresponding to the wavelengths, and the optical switches corresponding to different wavelengths are different.
  • the control unit is used to control the optical switch corresponding to the first wavelength in the optical switch group corresponding to each modulation unit 103 to turn on, and control the optical switch not corresponding to the first wavelength in the optical switch group to turn off; in this way, the light of the first wavelength in the optical switch group corresponding to each modulation unit 103 is transmitted to the first MUX and then output to the modulation unit.
  • the control unit is used to control the optical switch corresponding to the second wavelength in the optical switch group corresponding to each modulation unit 103 to turn on, and control the optical switch not corresponding to the second wavelength in the optical switch group to turn off; in this way, the light of the second wavelength in the optical switch group corresponding to each modulation unit 103 is transmitted to the first MUX and then output to the modulation unit.
  • the first DEMUX has an input terminal connected to the light source 101, and the first DEMUX has a plurality of output terminals connected one-to-one with the optical switches in the optical switch group corresponding to the at least one modulation unit 103.
  • the first MUX has a plurality of input terminals connected one-to-one with the optical switches in the optical switch group corresponding to the at least one modulation unit 103, and an output terminal connected to the at least one modulation unit 103.
  • the optical switches are connected to a control unit, and the control unit can determine the optical switches that need to be turned on and the optical switches that need to be turned off in the optical switch group.
  • the control unit can provide a control electrical signal for turning on the optical switch to the optical switch that needs to be turned on, and provide a control electrical signal for turning off the optical switch to the optical switch that needs to be turned off. It can be understood that the optical switches that need to be turned off can also be in the off state by default, and the control unit can also be free from providing control electrical signals to these optical switches.
  • the control unit can control the optical switch corresponding to the smallest wavelength among the 20 optical switches corresponding to the 20 wavelengths to turn on, and the other optical switches except the optical switch among the 20 optical switches to turn off. In this way, the switch unit can output the light with the smallest wavelength among the 20 wavelengths.
  • the switch unit 102 has one output port, which is applicable to the case where the optical transmitter includes one or more modulation units 103.
  • the second implementation of the switch unit 102 can be combined with each implementation of the light source 101.
  • the switch unit 102 includes: a first optical waveguide and a second optical waveguide, and a micro-ring group corresponding to the modulation unit 103.
  • the optical transmitter includes at least one modulation unit 103, so the switch unit 102 includes at least one micro-ring group corresponding to the at least one modulation unit 103.
  • FIG16 takes one micro-ring group corresponding to one modulation unit 103 as an example, and FIG17 takes multiple micro-ring groups corresponding to multiple modulation units 103 as an example.
  • An output port of the switch unit 102 is one end of the second optical waveguide.
  • the first optical waveguide and the second optical waveguide are both strip-shaped and extend in the same direction;
  • the microring group includes: along the arrangement direction of the first optical waveguide and the second optical waveguide, at least two switch microrings are arranged in sequence and spaced between the first optical waveguide and the second optical waveguide.
  • Figures 16 and 17 both take the microring group including two switch microrings (switch microrings are also called microring resonators) as an example;
  • Figure 17 takes the same microring groups as an example, it can be understood that the size and number of switch microrings in each microring group can also be different.
  • the first optical waveguide couples the switch microring adjacent to the first optical waveguide in the microring group
  • the second optical waveguide couples the switch microring adjacent to the second optical waveguide in the microring group
  • the adjacent switch microrings in the microring group are coupled to each other.
  • the two switch microrings in each microring group in Figures 16 and 17 are coupled to each other, and the upper switch microring is coupled to the second optical waveguide, and the lower switch microring is coupled to the first optical waveguide.
  • the radii of different switch microrings are different.
  • the at least one micro-ring group includes a plurality of micro-ring groups
  • the plurality of micro-ring groups are sequentially spaced and arranged along the extension direction of the first optical waveguide.
  • the first optical waveguide and the second optical waveguide may also be implemented in other ways, for example, the extension directions of the first optical waveguide and the second optical waveguide may be different (such as perpendicular).
  • the microring group may also include only one switch microring located between the first optical waveguide and the second optical waveguide, and the switch microring may be coupled to both the first optical waveguide and the second optical waveguide.
  • a modulation unit 103 (any modulation unit 103 in at least one modulation unit 103) and its corresponding wavelength group and microring group are taken as an example: the first optical waveguide is used to receive the light of the wavelength group corresponding to the modulation unit 103 emitted by the light source 101; the control unit can be connected to each switch microring, and the control unit is used to control the microring group to couple the light of the first wavelength in the light of the wavelength group transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit 103 in the first time period, and to control the microring group to couple the light of the second wavelength in the light of the wavelength group transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit 103 in the second time period.
  • the first optical waveguide is used to receive light of a wavelength group corresponding to each modulation unit 103 in the at least one modulation unit 103 emitted by the light source 101;
  • the control unit can be connected to each micro-ring group, and the control unit is used to control the micro-ring group corresponding to each modulation unit 103 to couple a wavelength (such as the first wavelength in the first time period or the second wavelength in the second time period) of the light of the wavelength group corresponding to the modulation unit transmitted in the first optical waveguide to the second optical waveguide for output.
  • the first optical waveguide has one end connected to the light source 101
  • the second optical waveguide has one end connected to the modulation unit 103.
  • the control unit is electrically connected to each microring group, and the control unit can provide a control electrical signal to the switch microring in the microring group according to the size of the microring group and the wavelength of the optical signal to be modulated by the modulation unit 103 corresponding to the microring group, so that the microring group can couple the optical signal of the wavelength from the first optical waveguide to the second optical waveguide.
  • the switch microring includes an annular optical waveguide and an electrode located around the annular optical waveguide, and only the annular optical waveguide in the switch microring is shown in Figures 16 and 17.
  • the control unit can be connected to the electrode to load a control electrical signal (current signal or voltage signal) to each electrode in the microring group, so that the microring group can couple the light of the wavelength transmitted in the first optical waveguide to the second optical waveguide.
  • the microring group When the microring group includes at least two switch microrings arranged in sequence and at intervals between the first optical waveguide and the second optical waveguide along the arrangement direction of the first optical waveguide and the second optical waveguide (as shown in FIG. 16 or FIG. 17), the microring group can couple light of one wavelength (such as the first wavelength in the first time period or the second wavelength in the second time period) in the light of the wavelength group corresponding to the modulation unit 103 transmitted on the first optical waveguide to the second optical waveguide based on the vernier caliper effect under the control of the control electrical signal provided by the control unit.
  • one wavelength such as the first wavelength in the first time period or the second wavelength in the second time period
  • each switch microring in the microring group can couple light of one wavelength set in the light of the wavelength group from the first optical waveguide under the control of the control electrical signal provided by the control unit; different switch microrings can couple light of different wavelength sets from the first optical waveguide under the control of the control electrical signal provided by the control unit, and at least two wavelength sets coupled by at least two switch microrings in the microring group under the control of the control electrical signal both include the above-mentioned one wavelength, and the at least two switch microrings can couple the light of the one wavelength to the second optical waveguide based on the vernier caliper effect.
  • the radius of the switch microring is related to the interval of the wavelength of light coupled from the first optical waveguide by the switch microring.
  • the interval of the wavelength of light coupled from the first optical waveguide by the switch microring with a larger radius is smaller, while the interval of the wavelength of light coupled from the first optical waveguide by the switch microring with a smaller radius is larger.
  • the radii of different switch microrings in the microring group are different, so the intervals of the wavelength of light coupled from the first optical waveguide by different switch microrings are different, so that different switch microrings couple light of different wavelength groups from the first optical waveguide.
  • the control electrical signal provided by the control unit to at least one switch microring in the microring group can be changed.
  • the control electrical signal loaded by the control unit to the switch microring changes, the wavelength of the light coupled from the first optical waveguide by the switch microring changes, but the interval of the wavelength of the light coupled from the first optical waveguide by the switch microring remains unchanged.
  • the microring group corresponding to the modulation unit 103 includes two switch microrings. If a switch microring with a larger radius can couple light with wavelengths 1, 5, 9, 13, and 17 from the first optical waveguide under the control of the control electrical signal provided by the control unit, and a switch microring with a smaller radius can couple light with wavelengths 2, 9, and 16 from the first optical waveguide under the control of the control electrical signal provided by the control unit, then the microring group can couple light with wavelength 9 to the second optical waveguide.
  • the control electrical signal provided by the control unit to a switch microring with a larger radius can be changed so that the switch microring with a larger radius couples light with wavelengths 2, 6, 10, 14, and 18 from the first optical waveguide, and thus the microring group can couple light with wavelength 2 to the second optical waveguide under the control of the control unit.
  • the control electrical signal provided by the control unit to a switch microring with a smaller radius can be changed so that the switch microring with a smaller radius couples light with wavelengths 3, 10, and 17 from the first optical waveguide, and thus the microring group can couple light with wavelength 17 to the second optical waveguide.
  • the switch unit 102 can be regarded as a filter.
  • the switch unit 102 uses a micro-ring group for filtering.
  • the filtering interval of the micro-ring group needs to be greater than the wavelength range of the multiple wavelengths provided by the light source 101. In this way, the micro-ring group can output light of one wavelength among the multiple wavelengths.
  • the filtering interval of the micro-ring group is the least common multiple of the filtering intervals of the switch micro-rings in the micro-ring group. Therefore, the filtering interval of the switch micro-rings in the micro-ring group can be set according to the required filtering interval of the micro-ring group.
  • the wavelength group can be 50 wavelengths arranged in sequence at intervals of 50 GHz in the range of 1529.16 nanometers to 1568.36 nanometers (i.e., 191.15 terahertz to 196.05 terahertz, about 4.9 terahertz).
  • the FSR of the switch microring ⁇ 2 /(2 ⁇ R ⁇ ng ), assuming that the group refractive index ng of the waveguide in the switch microring is 4, the larger radius of the two switch microrings can be set to about 480 microns, and the smaller radius can be set to about 9 microns.
  • the filtering interval of the switch microring with a larger radius is 25 GHz (ie, 0.2 nanometers)
  • the filtering interval of the switch microring with a smaller radius is 1.28 THz (ie, 10.24 nanometers)
  • the filtering interval of the microring group is 6.4 THz (greater than 4.9 THz).
  • the switch unit 102 has multiple output ports, which is applicable to the case where the optical transmitter includes multiple modulation units 103.
  • the third implementation of the switch unit 102 can be combined with each implementation of the light source 101.
  • the switch unit 102 includes: a first optical waveguide, a plurality of micro-ring groups corresponding to a plurality of modulation units 103, and a plurality of third optical waveguides corresponding to a plurality of modulation units 103.
  • the output port corresponding to the modulation unit 103 is one end of the third optical waveguide corresponding to the modulation unit 103.
  • FIG18 takes four modulation units 103 and four third optical waveguides as an example.
  • the wavelength group, micro-ring group and third optical waveguide corresponding to the modulation unit 103 Take a modulation unit 103 (any modulation unit 103 among multiple modulation units 103), the wavelength group, micro-ring group and third optical waveguide corresponding to the modulation unit 103 as an example: the first optical waveguide and the third optical waveguide are both strip-shaped and extend in the same direction; the micro-ring group includes: at least two switch micro-rings arranged in sequence and at intervals between the first optical waveguide and the third optical waveguide along the arrangement direction of the first optical waveguide and the third optical waveguide, and the radii of different switch micro-rings are different.
  • the first optical waveguide couples the switch micro-ring adjacent to the first optical waveguide in the micro-ring group
  • the second optical waveguide couples the switch micro-ring adjacent to the second optical waveguide in the micro-ring group
  • the adjacent switch micro-rings in the micro-ring group are coupled to each other.
  • the first optical waveguide is used to receive the light of the wavelength group emitted by the light source; the control unit is connected to the switch microring, and in the first time period, the control unit is used to control the microring group to couple the light of the first wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it to the modulation unit; in the second time period, the control unit is used to control the microring group to couple the light of the second wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it to the modulation unit.
  • the optical transmitter includes a plurality of modulation units 103
  • the switch unit 102 includes a plurality of micro-ring groups corresponding to the plurality of modulation units 103, and the plurality of micro-ring groups are arranged in sequence along the extension direction of the first optical waveguide.
  • FIG. 18 takes the same micro-ring groups as an example, and it can be understood that the size and number of the switch micro-rings in each micro-ring group may also be different.
  • the plurality of third optical waveguides corresponding to the plurality of modulation units 103 can be distributed on one side or both sides of the first optical waveguide.
  • FIG. 18 takes the example of four third optical waveguides distributed on both sides of the first optical waveguide, and two third optical waveguides distributed on each side of the first optical waveguide.
  • the first optical waveguide and the third optical waveguide may also be implemented in other ways, for example, the extension directions of the first optical waveguide and the third optical waveguide may be different (such as perpendicular).
  • the microring group may also include only one switch microring located between the first optical waveguide and the third optical waveguide corresponding to the microring group, and the switch microring may be coupled to both the first optical waveguide and the third optical waveguide.
  • the third implementable manner of the switch unit 102 is similar to the second implementable manner of the switch unit 102. The difference is that: in the second implementable manner of the switch unit 102, light of one wavelength in the wavelength group corresponding to each modulation unit 103 is output from the second optical waveguide, and the switch unit 102 has one output port; while in the third implementable manner of the switch unit 102, light of one wavelength in the wavelength group corresponding to each modulation unit 103 is output from the third optical waveguide corresponding to the micro-ring group corresponding to the modulation unit 103, and the switch unit 102 has multiple output ports.
  • the parts of the third implementable manner of the switch unit 102 other than the above-mentioned differences can refer to the second implementable manner of the switch unit 102, and the embodiments of the present application will not be described in detail here.
  • the modulation unit 103 may modulate light by in-phase orthogonal modulation or by direct modulation, which is not limited in the embodiments of the present application.
  • an in-phase orthogonal optical signal can be modulated, so that the optical signal modulated by the optical transmitter can be used for long-distance transmission, and the optical signal can be used in a long-distance wavelength division optical network.
  • the in-phase orthogonal modulation can be quadrature phase shift keying (QPSK) modulation, quadrature amplitude modulation (QAM), etc.
  • Direct modulation has only intensity modulation but no phase modulation. Direct modulation can be on-off keying modulation of "0" and “1", or four-level pulse amplitude modulation of "00", "01”, “10” and "11".
  • the modulation unit 103 is used to modulate light by in-phase orthogonal modulation, such as QPSK modulation or QAM.
  • the first implementable manner is applicable to the case where the optical transmitter includes one or more modulation units 103 and the switch unit 102 has one output port.
  • the first implementable manner of the modulation unit 103 can be combined with the first implementable manner or the second implementable manner of the switch unit 102.
  • FIG19 takes the optical transmitter including one modulation unit 103 as an example
  • FIG20 takes the optical transmitter including multiple modulation units 103 as an example.
  • the optical transmitter further includes: an MZI waveguide 105 and a phase shifter 106.
  • the MZI waveguide 105 includes: a first waveguide arm and a second waveguide arm connected in parallel and of equal length. One end of the first waveguide arm is connected to one end of the second waveguide arm, and the other end of the first waveguide arm is connected to the other end of the second waveguide arm.
  • the modulation unit 103 includes a first modulation microring and a second modulation microring, and both the first modulation microring and the second modulation microring can be referred to as MRMs.
  • the radius of the first modulation microring is the same as the radius of the second modulation microring; FIG.
  • each modulation unit is the same as an example, and it can be understood that the size of the first modulation microring in each modulation unit can also be different, and the size of the second modulation microring in each modulation unit can also be different.
  • the first modulation microring is spaced and coupled with the first waveguide arm, and the second modulation microring is spaced and coupled with the second waveguide arm, and the first modulation microring is not coupled with the second modulation microring.
  • the first modulation microring can be located on the side of the first waveguide arm away from the second waveguide arm, and the second modulation microring can be located on the side of the second waveguide arm away from the first waveguide arm.
  • the optical transmitter when the optical transmitter includes a plurality of modulation units 103, the plurality of modulation units 103 are sequentially arranged at intervals along the extension direction of the first waveguide arm.
  • the phase shifter 106 is located on the second waveguide arm and is located on a side of all the modulation units 103 (the above-mentioned at least one modulation unit 103) in the optical transmitter away from one end of the MZI waveguide 105.
  • one end of the MZI waveguide 105 is used to receive the light output by the switch unit (such as the light of the first wavelength in the first time period or the light of the second wavelength in the second time period); after receiving the light, one end of the MZI waveguide 105 can transmit the light to the first waveguide arm and the second waveguide arm.
  • the first modulation microring is used to perform phase shift keying modulation on the light transmitted in the first waveguide arm;
  • the second modulation microring is used to perform phase shift keying modulation on the light transmitted in the second waveguide arm;
  • the phase shifter 106 is used to perform 90 degree phase shift on the light passing through (the light modulated by the second modulation microring), such as the phase shifter performs 90 degree phase shift on the light by loading a voltage or a current.
  • the optical transmitter includes at least one modulation unit 103, and one end of the MZI waveguide 105 is used to receive light of a wavelength (such as the first wavelength in the first time period or the second wavelength in the second time period) in the wavelength group corresponding to each modulation unit 103 in the at least one modulation unit 103 output by the switch unit; the MZI waveguide 105 can also transmit these lights to the above-mentioned first waveguide arm and the second waveguide arm.
  • a wavelength such as the first wavelength in the first time period or the second wavelength in the second time period
  • the first modulation microring in each modulation unit is used to perform phase shift keying modulation on light of a wavelength in the wavelength group corresponding to the modulation unit transmitted in the first waveguide arm;
  • the second modulation microring in each modulation unit is used to perform phase shift keying modulation on light of a wavelength in the wavelength group corresponding to the modulation unit transmitted in the second waveguide arm;
  • the phase shifter 106 is used to perform 90-degree phase shift on the light (the light modulated by the second modulation microring), such as the phase shifter performs 90-degree phase shift on the light by loading a voltage or current.
  • the light output from the other end of the MZI waveguide includes: the optical signal modulated by each modulation unit.
  • the MZI waveguide may include not only a first waveguide arm and a second waveguide arm, but also a power splitting structure, and one end of the first waveguide arm and one end of the second waveguide arm are connected by a Y-shaped branch structure.
  • the power splitting structure is taken as an example of a Y-shaped branch structure, and the power splitting structure may also be a multimode interference structure, etc.
  • the Y-shaped branch structure may be located at one end of the MZI waveguide. After receiving light, one end of the MZI waveguide 105 may transmit the light to the first waveguide arm and the second waveguide arm using the power splitting structure.
  • the modulation microring may include a ring-shaped optical waveguide and an electrode located around the ring-shaped optical waveguide, and only the ring-shaped optical waveguide in the modulation microring is shown in Figures 19 and 20.
  • the electrode may be loaded with a driving signal and a bias voltage, so that the modulation microring can modulate light of any wavelength in the wavelength group corresponding to the modulation unit transmitted in the coupled waveguide arm.
  • the first modulation microring is used to perform binary phase shift keying (BPSK) modulation on the light of the wavelength transmitted in the first waveguide arm;
  • the second modulation microring is used to perform the same BPSK modulation on the light of the wavelength transmitted in the second waveguide arm;
  • the phase shifter 106 is used to perform 90-degree phase shift on the light passing through (the light modulated by the second modulation microring).
  • the optical signal output from the other end of the MZI is a QPSK optical signal.
  • the constellation diagram of the signal obtained after the first modulated microring performs BPSK modulation on the light of the wavelength transmitted in the first waveguide arm can be shown in FIG21; the constellation diagram of the signal obtained after the second modulated microring performs BPSK modulation on the light of the wavelength transmitted in the second waveguide arm can also be shown in FIG21; the constellation diagram of the signal obtained after the phase shifter 106 performs a 90-degree phase shift on the signal modulated by the second modulated microring can be shown in FIG22; the constellation diagram of the QPSK optical signal output from the other end of the MZI can be shown in FIG23.
  • the horizontal axis I is the in-phase axis
  • the vertical axis Q is the orthogonal axis
  • the black dots in the figure represent the optical signal
  • the distance of the black dots from the origin represents the intensity of the optical signal
  • the angle between the line connecting the black dots and the origin and the positive half axis of the I axis is the phase of the optical signal.
  • the two optical signals obtained after the phase shifter 106 performs a 90-degree phase shift on the signal obtained by the second modulated micro-ring modulation have the same intensity but opposite phases, and each of the two optical signals has a 90-degree phase difference with each optical signal in FIG. 21 .
  • the FSR of the modulation unit is related to the geometric parameters of the modulation unit, and the geometric parameters of the modulation unit can be set according to the required FSR.
  • the radii of the first modulation microring and the second modulation microring can be set to 240 microns, so that the FSR of the modulation unit 103 is 50GHz.
  • the modulation unit 103 is also used to modulate the optical signal by in-phase orthogonal modulation, such as QPSK modulation or QAM. Moreover, the second implementation is applicable to the case where the optical transmitter includes one modulation unit 103 (the number of the modulation unit 103 is 1) and the switch unit 102 has one output port. The second implementation of the modulation unit 103 can be combined with the first implementation or the second implementation of the switch unit 102.
  • the modulation unit 103 includes: a first non-equal arm MZM and a second non-equal arm MZM.
  • the optical transmitter also includes: an MZI waveguide 105 and a phase shifter 106.
  • the MZI waveguide includes: a first waveguide arm and a second waveguide arm connected in parallel and of equal length; the first non-equal arm MZM is located on the first waveguide arm, and the second non-equal arm MZM is located on the second waveguide arm; the phase shifter is located on the second waveguide arm, and is located on the side of the second non-equal arm MZM away from one end of the MZI waveguide; one end of the MZI waveguide is used to receive the light output by the switch unit; the first non-equal arm MZM is used to perform phase shift keying modulation on the light in the first waveguide arm; the second non-equal arm MZM is used to perform phase shift keying modulation on the light in the second waveguide arm; the phase shifter is used to perform 90 degree phase shift on the passing light.
  • the second implementable manner of the modulation unit 103 can refer to the first implementable manner of the modulation unit 103 mentioned above, which is applicable to the case of an optical transmitter including a modulation unit 103 (as shown in Figure 19).
  • the difference lies in that in the second implementable manner of the modulation unit 103, the non-equal-arm MZM is arranged on the waveguide arm, while in the first implementable manner of the modulation unit 103, the modulation microring is spaced from the waveguide arm.
  • the non-equal-arm MZM includes two parallel waveguide arms of unequal length and electrodes located around each waveguide arm, and only two parallel waveguide arms of unequal length in the non-equal-arm MZM are shown in Fig. 24.
  • Drive signals and bias voltages can be loaded on these electrodes, so that the non-equal-arm MZM can modulate light of any wavelength in the wavelength group corresponding to the modulation unit.
  • the FSR of the modulation unit is related to the geometric parameters of the modulation unit, and the geometric parameters of the modulation unit can be set according to the required FSR.
  • the modulation unit 103 is used to modulate the optical signal by direct modulation, and the direct modulation has only intensity modulation and no phase modulation. Moreover, the third implementation is applicable to the case where the optical transmitter includes one or more modulation units 103 and the switch unit 102 has one output port.
  • the third implementation of the modulation unit 103 can be combined with the first implementation or the second implementation of the switch unit 102. For example, FIG25 takes the optical transmitter including one modulation unit 103 as an example, and FIG26 takes the optical transmitter including multiple modulation units 103 as an example.
  • the optical transmitter further includes: a fourth optical waveguide 107
  • the modulation unit 103 includes: a modulation microring (also called MRM).
  • FIG. 26 takes the same modulation units as an example. It can be understood that the sizes of the modulation microrings in different modulation units may also be different.
  • the fourth optical waveguide 107 may be in the shape of a strip; the modulation microring is spaced and coupled with the fourth optical waveguide 107; when the optical transmitter includes a plurality of modulation units 103, the plurality of modulation microrings in the plurality of modulation units 103 are arranged in sequence along the extension direction of the fourth optical waveguide 107.
  • the fourth optical waveguide 107 is used to receive light of a wavelength in the wavelength group output by the switch unit 102 (such as the first wavelength in the first time period or the second wavelength in the second time period); the modulation microring is used to modulate the light on the fourth optical waveguide 107.
  • the optical transmitter includes at least one modulation unit, and the fourth optical waveguide 107 is used to receive light of a wavelength in the wavelength group corresponding to each modulation unit in the at least one modulation unit output by the switch unit 102; the modulation microring in each modulation unit is used to modulate light of any wavelength in the wavelength group corresponding to the modulation unit transmitted on the fourth optical waveguide 107.
  • the modulation microring in the modulation unit includes a ring-shaped optical waveguide and an electrode located around the ring-shaped optical waveguide, and only the ring-shaped optical waveguide in the modulation microring is shown in Figures 25 and 26.
  • the electrode can be loaded with a driving signal and a bias voltage, so that the modulation microring can modulate light of any wavelength in the wavelength group corresponding to the modulation unit transmitted in the coupled fourth optical waveguide.
  • the FSR of the modulation unit is related to the geometric parameters of the modulation unit, and the geometric parameters of the modulation unit can be set according to the required FSR. For example, it is assumed that the wavelengths in the wavelength group corresponding to the modulation unit all belong to the C band. For a modulation unit 103 shown in FIG25, the light source emits light of the wavelength group corresponding to the modulation unit 103, and the interval between adjacent wavelengths in the wavelength group is 50 GHz.
  • the light source emits light of multiple wavelengths with an interval of 50 GHz between adjacent wavelengths; the multiple wavelengths include the wavelength group corresponding to each modulation unit 103, and the interval between adjacent wavelengths in the wavelength group corresponding to each modulation unit 103 is 200 GHz.
  • the four modulation units 103 correspond to wavelengths of (200n+50) GHz, (200n+100) GHz, (200n+150) GHz, and (200n+200) GHz, respectively, where n ⁇ 0.
  • the FSR of each modulation unit 103 can be set to 200 GHz;
  • the modulation unit 103 is used to modulate the optical signal by direct modulation, and the fourth implementation is applicable to the case where the optical transmitter includes one modulation unit 103 (the number of the modulation unit 103 is 1) and the switch unit 102 has one output port.
  • the fourth implementation of the modulation unit 103 can be combined with the first implementation or the second implementation of the switch unit 102.
  • the modulation unit 103 includes: a non-equal-arm MZM, the non-equal-arm MZM includes two waveguide arms connected in parallel and having different lengths, and the two ends of the two waveguide arms are connected respectively.
  • the non-equal-arm MZM in the modulation unit includes two parallel waveguide arms of unequal length, and electrodes located around each waveguide arm, and only two parallel waveguide arms of unequal length in the non-equal-arm MZM are shown in Figure 27.
  • Drive signals and bias voltages can be loaded on these electrodes, so that the non-equal-arm MZM can modulate light of any wavelength in the wavelength group corresponding to the modulation unit passing through.
  • the modulation unit 103 is used to modulate the optical signal by in-phase orthogonal modulation (or direct modulation), and the fifth implementation is applicable to the case where the optical transmitter includes a plurality of modulation units 103 (the number of modulation units 103 is greater than 1) and the switch unit 102 has one output port.
  • the fifth implementation of the modulation unit 103 can be combined with the first implementation or the second implementation of the switch unit 102.
  • the optical transmitter further includes: a second DEMUX 108 and a second MUX 109; taking a modulation unit 103 (any modulation unit in the optical transmitter) and its corresponding wavelength group as an example: the second DEMUX 108 is used to receive light of a wavelength in the wavelength group (such as the first wavelength in the first time period or the second wavelength in the second time period), and transmit the light to the modulation unit 103; the modulation unit 103 is used to modulate the light into an optical signal and transmit it to the second MUX 109; the second MUX 109 is used to receive and output the optical signal modulated by the modulation unit 103.
  • the modulation unit 103 can be any unit that can modulate light.
  • the optical transmitter includes a plurality of modulation units 103, and the second DEMUX 108 is used to receive light of a wavelength in a wavelength group corresponding to each modulation unit 103 in the plurality of modulation units, and transmit the light of a wavelength in the wavelength group corresponding to each modulation unit 103 to the modulation unit 103; each modulation unit 103 is used to modulate the light of the wavelength in the corresponding wavelength group into an optical signal, and then transmit it to the second MUX 109; the second MUX 109 is used to receive and output the optical signal modulated by each modulation unit 103.
  • the modulation unit 103 is used to modulate the optical signal by in-phase orthogonal modulation (or direct modulation), and the sixth implementation is applicable to the case where the optical transmitter includes a plurality of modulation units 103 and the switch unit 102 has a plurality of output ports (such as the third implementation of the switch unit 102 mentioned above).
  • the sixth implementation of the modulation unit 103 can be combined with the third implementation of the switch unit 102.
  • the optical transmitter also includes: a second MUX 109; taking a modulation unit 103 (any modulation unit in the optical transmitter) and its corresponding wavelength group as an example: the modulation unit is used to receive light of a wavelength in the wavelength group (such as the first wavelength in the first time period or the second wavelength in the second time period) output by the corresponding output port in the switch unit, and modulate the light of the one wavelength into an optical signal; the second MUX 109 is used to receive and output the optical signal.
  • a modulation unit 103 any modulation unit in the optical transmitter
  • the modulation unit is used to receive light of a wavelength in the wavelength group (such as the first wavelength in the first time period or the second wavelength in the second time period) output by the corresponding output port in the switch unit, and modulate the light of the one wavelength into an optical signal
  • the second MUX 109 is used to receive and output the optical signal.
  • the modulation unit 103 may be any structure capable of modulating light.
  • the modulation unit 103 may adopt the structure shown in FIG. 24 .
  • the implementable manner of the light source 101, the implementable manner of the switch unit 102 and the implementable manner of the modulation unit 103 provided in the embodiment of the present application can be combined.
  • the optical source 101 can use the implementable method in (1.1), (1.2) or (1.3); the switch unit 102 can use the implementable method in (2.2); and the modulation unit 103 can use the implementable method in (3.1) or (3.2).
  • the optical transmitter needs to transmit optical signals of multiple wavelengths, and the wavelengths match the DWDM standard, and the optical signals are modulated by in-phase orthogonal modulation.
  • the light source 101 can adopt the implementable method in (1.1), (1.2) or (1.3).
  • the switch unit 102 can adopt the implementable method in (2.1) or (2.2), and the modulation unit 103 can adopt the implementable method in (3.1) or (3.5); or, the switch unit 102 can adopt the implementable method in (2.3), and the modulation unit 103 can adopt the implementable method in (3.6).
  • the optical transmitter needs to transmit optical signals of multiple wavelengths, and the optical signals are modulated by direct modulation.
  • the light source 101 can adopt the implementable method in (1.1), (1.2) or (1.3);
  • the switch unit 102 can adopt the implementable method in (2.2); and
  • the modulation unit 103 can adopt the implementable method in (3.3).
  • optical transmitter provided in the embodiment of the present application may also include other units in addition to the units introduced above, and the embodiment of the present application is not limited to this.
  • the optical transmitter may further include a power amplifier unit, such as an on-chip erbium-doped silicon nitride waveguide or an erbium-doped fiber amplifier, etc.
  • the power amplifier unit is located between the light source and the switch unit, and is used to amplify the power of the light emitted by the light source and transmit it to the switch unit.
  • the optical transmitter may further include a power beam splitter, which is used to split the light emitted by the light source pool into multiple beams of light and transmit one of the beams of light to the switch unit.
  • the light source can provide light of at least one wavelength group to the switch unit, and the control unit can control the switch unit to output light of the first wavelength or the second wavelength in the corresponding wavelength group to each modulation unit, so that the modulation unit can modulate the received light. Since the difference between the first wavelength and the second wavelength in the wavelength group corresponding to the modulation unit is an integer multiple of the FSR of the modulation unit, and the wavelength of the light input to the modulation unit by the switch unit can be switched between the first wavelength and the second wavelength, when the optical transmitter needs to switch the wavelength of the optical signal between the first wavelength and the second wavelength, the modulation unit does not need to change the bias voltage, and the light source does not need to change the light provided.
  • the control unit only needs to control the switch unit to output the light of the switched wavelength. It can be seen that the process of switching the wavelength of the optical signal of the optical transmitter is relatively simple.
  • the structure of the optical transmitter provided in the embodiment of the present application is simple.
  • the optical transmitter does not require a pump light source and a nonlinear device, so there is no problem of high power consumption introduced by the pump light source, and there is no problem of noise introduced by the nonlinear device, and it does not affect the quality of the optical signal and the link transmission performance (such as optical signal-to-noise ratio (OSNR)).
  • OSNR optical signal-to-noise ratio
  • the optical transmitter can include multiple modulation units, but only one light source and one switch unit are required, and the cost and power consumption of the optical transmitter are low.
  • the optical transmitter provided in the embodiment of the present application does not use the photoelectric conversion method to switch the wavelength of the optical signal.
  • the performance requirements of each part of the optical transmitter in the present application are low, so it is less likely to introduce noise and the problem of information loss carried by the optical signal.
  • the optical transmitter provided in the embodiment of the present application does not limit the modulation method of the modulation unit, and the modulation unit can modulate light using the same direction orthogonal modulation method or the direct modulation method.
  • the embodiment of the present application further provides an optical transmission method, which is used for any optical transmitter provided in the present application.
  • the optical transmission method includes:
  • a light source provides light of multiple wavelengths to a switch unit, wherein the multiple wavelengths include a first wavelength and a second wavelength, and a difference between the first wavelength and the second wavelength is an integer multiple of an FSR of a modulation unit;
  • control unit controls the switch unit to output light of a first wavelength to the modulation unit, and the modulation unit modulates the input light of the first wavelength to output modulated light of the first wavelength;
  • control unit controls the switch unit to output light of a second wavelength to the modulation unit, and the modulation unit modulates the input light of the second wavelength to output modulated light of the second wavelength.
  • the switch control method involved in the control unit may include:
  • the control unit controls the switch unit to output light of a first wavelength among multiple wavelengths of light provided by the light source to the modulation unit, so that the modulation unit modulates the input light of the first wavelength to output modulated light of the first wavelength;
  • the multiple wavelengths include a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit.
  • control unit controls the switch unit to output light of a second wavelength among the multiple wavelengths of light provided by the light source to the modulation unit, so that the modulation unit modulates the input light of the second wavelength to output modulated light of the second wavelength.
  • the difference between the first wavelength and the second wavelength is FSR.
  • the optical transmitter includes: a plurality of modulation units; the plurality of wavelengths of light emitted by the light source include: a plurality of wavelength groups corresponding to the plurality of modulation units one by one; for a wavelength group corresponding to a modulation unit, the wavelength group includes a first wavelength and a second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit; the first wavelengths in different wavelength groups are different, and the second wavelengths in different wavelength groups are different.
  • control unit may control the switch unit to output the light of the first wavelength in the corresponding wavelength group to the modulation unit; in S103, the control unit may control the switch unit to output the light of the second wavelength in the corresponding wavelength group to the modulation unit.
  • the light emission method provided in the embodiment of the present application is related to the implementable manner of the switch unit.
  • the switch unit adopts the implementable method described in (2.1) above, taking a modulation unit as an example, in S101, the light source provides the light of the wavelength group corresponding to the modulation unit to the first DEMUX.
  • the control unit controls the optical switch group to transmit the light of the first wavelength in the wavelength group to the first MUX and then to the modulation unit; in S103, the control unit controls the optical switch group to transmit the light of the second wavelength in the wavelength group to the first MUX and then to the modulation unit.
  • the switch unit adopts the implementable method described in (2.2) above, taking a modulation unit as an example, in S101, the light source provides the light of the wavelength group corresponding to the modulation unit to the first optical waveguide.
  • the control unit controls the micro-ring group to couple the light of the first wavelength transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit; in S103, the control unit controls the micro-ring group to couple the light of the second wavelength transmitted in the first optical waveguide to the second optical waveguide and then output it to the modulation unit.
  • the light source provides light of multiple wavelengths to the first optical waveguide.
  • the control unit can control the micro-ring group to couple the light of the first wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it, and in S103, the control unit can control the micro-ring group to couple the light of the second wavelength in the wavelength group transmitted in the first optical waveguide to the third optical waveguide and then output it.
  • control unit needs to include hardware and/or software modules that perform the corresponding functions.
  • present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application in conjunction with the embodiments, but such implementation should not be considered to be beyond the scope of the present application.
  • This embodiment can divide the functional modules of the corresponding control unit according to the above method embodiment.
  • each functional module can be divided according to each function, or two or more functions can be integrated into one processing module.
  • the above integrated module can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is schematic, specifically as a possible division method of a logical function, and there may be other division methods in actual implementation.
  • the switch control device belonging to the control unit provided by the present application will be described below in conjunction with Figure 32.
  • the switch control device includes: a first control module 301 and a second control module 302.
  • the first control module 301 is used to control the switch unit to output the first wavelength of light among the multiple wavelengths of light provided by the light source to the modulation unit in the first time period, so that the modulation unit modulates the input first wavelength of light to output modulated light of the first wavelength;
  • the multiple wavelengths include the first wavelength and the second wavelength, and the difference between the first wavelength and the second wavelength is an integer multiple of the FSR of the modulation unit;
  • the second control module 302 is used to control the switch unit to output the second wavelength of light among the multiple wavelengths of light provided by the light source to the modulation unit in the second time period, so that the modulation unit modulates the input second wavelength of light to output modulated light of the second wavelength.
  • the switch control device belonging to the control unit provided in the present application includes: a processor and a memory, in which a program is stored, and the processor is used to execute the program stored in the memory to implement any switch control method provided in the examples of the present application and executed by the control unit.
  • An embodiment of the present application also provides a chip, which includes a programmable logic circuit and/or program instructions. When the chip is running, it is used to implement any switch control method performed by a control unit provided in the example of the present application.
  • An embodiment of the present application also provides a computer-readable storage medium, in which instructions are stored.
  • the instructions When the instructions are executed on a computer, the computer executes any one of the switch control methods performed by the control unit provided in the example of the present application.
  • An embodiment of the present application also provides a computer program product comprising instructions.
  • the computer program product When the computer program product is run on a computer, the computer is enabled to execute any one of the switch control methods performed by the control unit provided in the example of the present application.
  • any of the above-mentioned switch control method embodiments executed by the control unit can be implemented in whole or in part by software, hardware, firmware or any combination thereof.
  • software When implemented using software, it can be implemented in whole or in part in the form of a computer program product, and the computer program product includes one or more computer instructions.
  • the computer program instructions When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part.
  • the computer can be a general-purpose computer, a computer network, or other programmable device.
  • the computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means.
  • the computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes one or more available media integrated.
  • the available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium, or a semiconductor medium (e.g., a solid-state hard disk), etc.
  • first and second are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.
  • the term “at least one” means one or more, and “plurality” means two or more, unless otherwise clearly defined.
  • the various different types of embodiments provided in the embodiments of the present application can refer to each other, and the embodiments of the present application are not limited to this.
  • the disclosed optical transmitter, optical module, optical communication equipment, optical communication system, optical transmission method, switch control method and device, etc. can be implemented by other configuration methods.
  • the embodiments described above are only schematic, for example, the division of units or modules is only a logical function division, and there may be other division methods in actual implementation, for example, multiple units or modules can be combined or integrated, or some features can be ignored or not executed.
  • the units described as separate components may or may not be physically separated, and the components described as units may or may not be physical units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

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Abstract

一种光发射机、光发射方法、光模块、设备及系统，涉及光通信技术领域，光发射机包括光源、开关单元、调制单元和控制单元，光源用于向开关单元提供多个波长的光；控制单元用于在第一时间段内控制开关单元向调制单元输出第一波长的光，以及在第二时间段内控制开关单元输出第二波长的光；调制单元用于在第一时间段内对输入的第一波长的光进行调制，以输出第一波长的调制光，以及在第二时间段内对输入的第二波长的光进行调制，以输出第二波长的调制光。本申请能够解决光发射机切换光信号的波长的过程较为繁琐的问题，本申请用于光发射机。

Description

光发射机、光发射方法、光模块、设备及系统 技术领域
本申请涉及光通信技术领域，特别涉及一种光发射机、光发射方法、光模块、设备及系统。
背景技术
光通信设备之间通过光信号进行通信。光发射机是光通信设备中的重要模块，光发射机包括光源和调制单元，其中，光源用于向调制单元提供一种波长的光，调制单元用于对该光进行调制，得到光通信设备需要传输的光信号。
光发射机存在切换光信号的波长的情况。示例地，光发射机在切换光信号的波长时，光发射机的光源切换向调制单元提供的光的波长，并且，光发射机需要根据切换后的光的波长对调制单元的偏置电压进行调整，以使调制单元能够对切换波长后的光进行调制。
但是，由于光发射机切换光信号的波长的过程中，不仅需要切换光源提供的光的波长，而且还要调整调制单元的偏置电压，因此，光发射机切换光信号的波长的过程较为繁琐。
发明内容
本申请提供了一种光发射机、光发射方法、光模块、设备及系统，能够解决光发射机切换光信号的波长的过程较为繁琐的问题。
第一方面，提供了一种光发射机，包括：光源、开关单元、调制单元和控制单元。其中，所述光源用于向所述开关单元提供多个波长的光；所述控制单元用于在第一时间段内控制所述开关单元向所述调制单元输出所述多个波长中第一波长的光，以及在第二时间段内控制所述开关单元向所述调制单元输出所述多个波长中第二波长的光；所述调制单元用于在所述第一时间段内对输入的所述第一波长的光进行调制，以输出所述第一波长的调制光，以及在所述第二时间段内对输入的所述第二波长的光进行调制，以输出所述第二波长的调制光。
其中，第一波长和第二波长之差为调制单元的自由光谱范围(free spectral range，FSR)的整数倍，比如，第一波长和第二波长之差为该FSR。
本申请实施例提供的光发射机中，光源能够向开关单元提供多个波长的光，并且，控制单元能够控制开关单元向调制单元输出该多个波长中第一波长或第二波长的光，以便于调制单元对接收到的光进行调制。由于第一波长和第二波长之差为调制单元的FSR的整数倍，且开关单元输入调制单元的光的波长能够在第一波长和第二波长之间切换，因此，在光发射机需要将光信号的波长在第一波长和第二波长之间切换时，调制单元无需改变偏置电压，光源也无需改变提供的光，只需控制单元控制开关单元输出切换后的波长的光即可。可见，该光发射机切换光信号的波长的过程较为简单。
通常控制单元控制开关单元切换输出的光的波长的速度较快，因此，光发射机切换光信号的波长的速度也较快，光发射机所在的光通信设备切换发出的光信号的波长的速度也较快。本申请提供的光发射机切换光信号的波长的时间能够控制在50毫秒以内，能够实现业务的 “无缝衔接”，不影响业务的连续性和一致性。示例地，在上述开关单元为基于热光效应的开关单元(可以称为热光开关)时，光发射机切换光信号的波长所需的时长为毫秒级时长；在上述开关单元为基于电光效应的开关单元(可以称为电光开关)时，光发射机切换光信号的波长所需的时长为纳秒级时长。相比前述相关技术中光发射机切换光信号的波长需要几十秒的时长，本申请实施例提供的光发射机切换光信号的波长的时长降低了千倍甚至百万倍。以上以光发射机包括一个调制单元为例，可以理解的是，光发射机也可以包括多个调制单元；不同调制单元的FSR可以相同也可以不同。在光发射机包括多个调制单元时，上述多个波长包括：该多个调制单元一一对应的多个波长组。对于一个调制单元对应的波长组，该波长组包括第一波长和第二波长，且第一波长和第二波长之差为该调制单元的FSR的整数倍。不同波长组可以相同也可以不同，不同波长组中的第一波长不同，不同波长组中的第二波长不同。这种情况下，控制单元用于：在第一时间段内控制开关单元向调制单元输出对应的波长组中第一波长的光，以及在第二时间段内控制开关单元向调制单元输出对应的波长组中第二波长的光。
可以理解的是，每个波长组除了包括第一波长和第二波长之外，可以不包括其他波长，也可以还包括其他波长，本申请实施例对此不作限定。并且，在波长组包括该其他波长时，波长组中任意两个波长之差均可以是该波长组对应的调制单元的FSR的整数倍。
进一步地，本申请中，光源、开关单元和调制单元均可以有多种可实现方式，以下将分别对光源、开关单元和调制单元中每个部分的多种可实现方式进行介绍。
(1)光源。光源可以包括量子点锁模激光器(quantum dot mode locked laser，QDMLL)、量子阱锁模激光器(quantum well mode locked laser，QWMLL)、光频梳或光源池。
(2)开关单元。
开关单元可以具有一个出端口，开关单元用于从该出端口向每个调制单元输出光。比如，在第一时间段，开关单元用于从该出端口向每个调制单元输出该调制单元对应的波长组中第一波长的光。在第二时间段，开关单元用于从该出端口向每个调制单元输出该调制单元对应的波长组中第二波长的光。这种情况适用于光发射机包括一个或多个调制单元的情况。
或者，在光发射机包括多个调制单元时，开关单元具有与该多个调制单元一一对应的多个出端口，开关单元用于从调制单元对应的出端口向该调制单元输出光。比如，在第一时间段，开关单元用于从调制单元对应的出端口向该调制单元输出该调制单元对应的波长组中第一波长的光。在第二时间段，开关单元用于从调制单元对应的出端口向该调制单元输出该调制单元对应的波长组中第二波长的光。
(2.1)在开关单元的第一种可实现方式中，开关单元具有一个出端口，这种情况适用于光发射机包括一个或多个调制单元的情况。开关单元的第一种可实现方式可以与光源的每种可实现方式结合。
所述开关单元包括：第一波分解复用器(de-multiplexer，DEMUX)和第一波分复用器(multiplexer，MUX)，以及与所述至少一个调制单元一一对应的至少一个光开关组；所述开关单元的出端口为所述第一MUX的出端口；对于所述一个调制单元：所述第一DEMUX用于接收该调制单元对应的波长组的光；所述调制单元对应的所述光开关组包括：与该波长组中的波长一一对应的多个光开关；所述第一DEMUX用于将该波长组中各个波长的光分别传输至对应的所述光开关；在第一时间段，控制单元用于控制该光开关组中对应第一波长的 光开关导通，以及控制该光开关组中不对应第一波长的光开关关断；这样一来，该波长组中第一波长的光传输至第一MUX后输出至该调制单元，而该波长组中除第一波长之外的其他波长的光无法传输至第一MUX并输出至该调制单元。在第二时间段，控制单元用于控制该光开关组中对应第二波长的光开关导通，以及控制该光开关组中不对应第二波长的光开关关断；这样一来，该波长组中第二波长的光传输至第一MUX后输出至该调制单元，而该波长组中除第二波长之外的其他波长的光无法传输至第一MUX并输出至该调制单元。
(2.2)在开关单元的第二种可实现方式中，开关单元具有一个出端口，这种情况适用于光发射机包括一个或多个调制单元的情况。开关单元的第二种可实现方式可以与光源的每种可实现方式结合。
所述开关单元包括：第一光波导和第二光波导，以及与所述至少一个调制单元一一对应的至少一个微环组；所述开关单元的出端口为所述第二光波导的一端；所述第一光波导和所述第二光波导均呈条状，且延伸方向相同；所述微环组包括：沿所述第一光波导和所述第二光波导的排布方向，依次间隔地排布在所述第一光波导和所述第二光波导之间的至少两个开关微环，不同所述开关微环的半径不同；所述第一光波导耦合所述微环组中与所述第一光波导相邻的所述开关微环，所述第二光波导耦合所述微环组中与所述第二光波导相邻的所述开关微环，所述微环组中相邻的所述开关微环之间互相耦合；在所述至少一个微环组包括多个微环组时，所述多个微环组沿所述第一光波导的延伸方向依次间隔排布；对于所述一个调制单元对应的波长组和所述微环组：所述第一光波导用于接收所述光源发出的该波长组的光；在第一时间段，所述控制单元用于控制所述微环组将所述第一光波导中传输的该波长组中第一波长的光耦合至所述第二光波导后输出；在第二时间段，所述控制单元用于控制所述微环组将所述第一光波导中传输的该波长组中第二波长的光耦合至所述第二光波导后输出。
(2.3)在开关单元的第三种可实现方式中，开关单元具有多个出端口，这种情况适用于光发射机包括多个调制单元的情况。开关单元的第三种可实现方式可以与光源的每种可实现方式结合。
所述开关单元包括：第一光波导，与所述多个调制单元一一对应的多个微环组，以及与所述多个调制单元一一对应的多个第三光波导；所述调制单元对应的所述出端口为所述调制单元对应的所述第三光波导的一端；对于所述一个调制单元对应的所述微环组和所述第三光波导：所述第一光波导和所述第三光波导均呈条状，且延伸方向相同；所述微环组包括：沿所述第一光波导和所述第三光波导的排布方向，依次间隔地排布在所述第一光波导和所述第三光波导之间的至少两个开关微环，不同所述开关微环的半径不同；所述第一光波导耦合所述微环组中与所述第一光波导相邻的所述开关微环，所述第二光波导耦合所述微环组中与所述第二光波导相邻的所述开关微环，所述微环组中相邻的所述开关微环之间互相耦合；所述多个微环组沿所述第一光波导的延伸方向依次间隔排布；所述第一光波导用于接收所述光源发出的调制单元对应的波长组的光；在第一时间段，所述控制单元用于控制所述微环组将所述第一光波导中传输的该波长组中第一波长的光耦合至所述第三光波导后输出至该调制单元；在第二时间段，所述控制单元用于控制所述微环组将所述第一光波导中传输的该波长组中第二波长的光耦合至所述第三光波导后输出至该调制单元。
(3)调制单元。
调制单元可以采用同相正交调制的方式调制光信号，也可以不采用同相正交调制的方式 (如直接调制的方式)调制光信号，本申请对此不做限定。
(3.1)在调制单元的第一种可实现方式中，调制单元用于采用同相正交调制的方式调制光。并且，该第一种可实现方式适用于光发射机包括一个或多个调制单元，开关单元具有一个出端口的情况。调制单元的第一种可实现方式可以与开关单元的第一种可实现方式或第二种可实现方式结合。
示例地，所述光发射机还包括：马赫增德干涉仪(mach-zehnder interferometer，MZI)波导和移相器；所述MZI波导包括：并联且等长的第一波导臂和第二波导臂；所述调制单元包括：第一调制微环和第二调制微环；所述第一调制微环的半径与所述第二调制微环的半径相同；所述第一调制微环与所述第一波导臂间隔且耦合，所述第二调制微环与所述第二波导臂间隔且耦合；在所述至少一个调制单元包括多个调制单元时，所述多个调制单元沿所述第一波导臂的延伸方向依次间隔排布；所述移相器位于所述第二波导臂上，且位于所述至少一个调制单元远离所述MZI波导的一端的一侧；对于一个所述调制单元及其对应的波长组：在第一时间段，所述MZI波导的一端用于接收所述开关单元输出的该波长组中第一波长的光；所述第一调制微环用于对所述第一波导臂中该第一波长的光进行相移键控调制；所述第二调制微环用于对所述第二波导臂中该第一波长的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。在第二时间段，所述MZI波导的一端用于接收所述开关单元输出的该波长组中第二波长的光；所述第一调制微环用于对所述第一波导臂中该第二波长的光进行相移键控调制；所述第二调制微环用于对所述第二波导臂中该第二波长的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。
(3.2)在调制单元的第二种可实现方式中，调制单元也用于采用同相正交调制的方式调制光信号。并且，该第二种可实现方式适用于光发射机包括一个调制单元，开关单元具有一个出端口的情况。调制单元的第二种可实现方式可以与开关单元的第一种可实现方式或第二种可实现方式结合。
所述调制单元包括：第一非等臂马赫增德调制器(mach-zehnder modulator，MZM)、第二非等臂MZM；光发射机还包括MZI波导和移相器。所述MZI波导包括：并联且等长的第一波导臂和第二波导臂；所述第一非等臂MZM位于所述第一波导臂上，所述第二非等臂MZM位于所述第二波导臂上；所述移相器位于所述第二波导臂上，且位于所述第二非等臂MZM远离所述MZI波导的一端的一侧。在第一时间段，所述MZI波导的一端用于接收所述开关单元输出的该调制单元对应的波长组中第一波长的光；所述第一非等臂MZM用于对所述第一波导臂中所述第一波长的光进行相移键控调制；所述第二非等臂MZM用于对所述第二波导臂中所述第一波长的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。在第二时间段，所述MZI波导的一端用于接收所述开关单元输出的该调制单元对应的波长组中第二波长的光；所述第一非等臂MZM用于对所述第一波导臂中所述第二波长的光进行相移键控调制；所述第二非等臂MZM用于对所述第二波导臂中所述第二波长的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。
(3.3)在调制单元的第三种可实现方式中，调制单元用于采用直接调制的方式调制光信号，直接调制只有强度调制，无相位调制。并且，该第三种可实现方式适用于光发射机包括一个或多个调制单元，开关单元具有一个出端口的情况。调制单元的第三种可实现方式可以与开关单元的第一种可实现方式或第二种可实现方式结合。
示例地，所述光发射机还包括：第四光波导，所述调制单元包括：调制微环；所述第四光波导呈条状；所述调制微环与所述第四光波导间隔且耦合；在所述至少一个调制单元包括多个调制单元时，所述多个调制单元中的多个调制微环沿所述第四光波导的延伸方向依次排布；对于所述一个调制单元及其对应的波长组：在第一时间段，所述第四光波导用于接收所述开关单元输出的该波长组中第一波长的光，所述调制微环用于对所述第四光波导上的所述第一波长的光进行调制。在第二时间段，所述第四光波导用于接收所述开关单元输出的该波长组中第二波长的光，所述调制微环用于对所述第四光波导上的所述第二波长的光进行调制。
(3.4)在调制单元的第四种可实现方式中，调制单元用于采用直接调制的方式调制光信号，并且，该第四种可实现方式适用于光发射机包括一个调制单元，开关单元具有一个出端口的情况。调制单元的第四种可实现方式可以与开关单元的第一种可实现方式或第二种可实现方式结合。在调制单元的第四种可实现方式中，调制单元包括：非等臂MZM，非等臂MZM包括并联且长度不同的两个波导臂，这两个波导臂的两端分别连接。
(3.5)在调制单元的第五种可实现方式中，调制单元用于采用同相正交调制(或直接调制)的方式调制光信号，并且，该第五种可实现方式适用于光发射机包括多个调制单元，开关单元具有一个出端口的情况。调制单元的第五种可实现方式可以与开关单元的第一种可实现方式或第二种可实现方式结合。示例地，所述至少一个调制单元包括多个调制单元；所述光发射机还包括：第二DEMUX和第二MUX；对于所述一个调制单元及其对应的波长组：在第一时间段，所述第二DEMUX用于接收所述波长组中第一波长的光，并将所述第一波长的光传输至所述调制单元；所述调制单元用于对所述第一波长的光进行调制；所述第二MUX用于接收并输出所述调制单元调制得到的光信号。在第二时间段，所述第二DEMUX用于接收所述波长组中第二波长的光，并将所述第二波长的光传输至所述调制单元；所述调制单元用于对所述第二波长的光进行调制；所述第二MUX用于接收并输出所述调制单元调制得到的光信号。
(3.6)在调制单元的第六种可实现方式中，调制单元用于采用同相正交调制(或直接调制)的方式调制光信号，并且，该第六种可实现方式适用于光发射机包括多个调制单元，并且开关单元具有多个出端口的情况。调制单元的第六种可实现方式可以与开关单元的第三种可实现方式结合。示例地，所述光发射机还包括：第二MUX；对于所述一个调制单元及其对应的波长组：在第一时间段，所述调制单元用于接收所述开关单元中对应的所述出端口输出的所述波长组中第一波长的光，并对所述第一波长的光进行调制；所述第二MUX用于接收并输出所述调制单元调制得到的光信号。在第二时间段，所述调制单元用于接收所述开关单元中对应的所述出端口输出的所述波长组中第二波长的光，并对所述第二波长的光进行调制；所述第二MUX用于接收并输出所述调制单元调制得到的光信号。
第二方面，本申请还提供了一种光发射方法，该方法由第一方面提供的任一种光发射机执行，对于光发射机中的至少一个调制单元中的一个调制单元(任一个调制单元)，该光发射方法包括：光源向开关单元提供多个波长的光，其中，多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍；在第一时间段内，控制单元控制开关单元向调制单元输出第一波长的光，调制单元对输入的第一波长的光进行调制，以输出第一波长的调制光；在第二时间段内，控制单元控制开关单元向调制单元输出第二波长的光，调制单元对输入的第二波长的光进行调制，以输出第二波长的调制光。
可选地，第一波长与第二波长之差为FSR。
可选地，光发射机包括：多个调制单元；光源发出的光的多个波长包括：多个调制单元一一对应的多个波长组；对于一个调制单元对应的波长组，该波长组包括第一波长和第二波长，且第一波长和第二波长之差为该调制单元的FSR的整数倍；不同波长组中的第一波长不同，不同波长组中的第二波长不同。在第一时间段，控制单元可以控制开关单元向该调制单元输出对应的波长组中第一波长的光；在第二时间段，控制单元可以控制开关单元向调制单元输出对应的波长组中第二波长的光。
本申请实施例提供的光发射方法与开关单元的可实现方式相关。
当开关单元采用上述(2.1)中所述的可实现方式时，以一个调制单元为例，光源向第一DEMUX提供该调制单元对应的波长组的光。在第一时间段，控制单元控制光开关组将该波长组中第一波长的光传输至第一MUX后传输至该调制单元；在第二时间段，控制单元控制光开关组将该波长组中第二波长的光传输至第一MUX后传输至该调制单元。
当开关单元采用上述(2.2)中所述的可实现方式时，以一个调制单元为例，光源向第一光波导提供该调制单元对应的波长组的光。在第一时间段，控制单元控制微环组将第一光波导中传输的第一波长的光耦合至第二光波导后输出至调制单元；在第二时间段，控制单元控制微环组将第一光波导中传输的第二波长的光耦合至第二光波导后输出至调制单元。
当开关单元采用上述(2.3)中所述的可实现方式时，光源向第一光波导提供多个波长的光。对于一个调制单元对应的波长组、微环组和第三光波导，在第一时间段，控制单元可以控制微环组将第一光波导中传输的波长组中第一波长的光耦合至第三光波导后输出，在第二时间段，控制单元可以控制微环组将第一光波导中传输的波长组中第二波长的光耦合至第三光波导后输出。
第三方面，提供了一种开关控制方法，该方法可以由第一方面提供的任一种光发射机中的控制单元执行，该方法包括：在第一时间段内，控制单元控制开关单元向调制单元输出光源提供的多个波长的光中第一波长的光，以便于调制单元对输入的第一波长的光进行调制，以输出第一波长的调制光；在第二时间段内，控制单元控制开关单元向调制单元输出光源提供的多个波长的光中第二波长的光，以便于调制单元对输入的第二波长的光进行调制，以输出第二波长的调制光。其中，该多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍。
第四方面，提供了一种开关控制装置，该开关控制装置属于第一方面中任一设计所述的光发射机中的控制单元，该开关控制装置包括用于执行第三方面提供的控制方法的各个模块。
第五方面，提供了一种开关控制装置，该开关控制装置包括：处理器和存储器，存储器中存储有程序，处理器用于执行存储器中存储的程序，以实现第三方面所述的方法。
第六方面，提供了一种芯片，所述芯片包括可编程逻辑电路和/或程序指令，当所述芯片运行时用于实现如第三方面所述的方法。
第七方面，提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当所述指令在计算机上运行时，使得计算机执行如第三方面所述的方法。
第八方面，提供了一种包含指令的计算机程序产品，当所述计算机程序产品在计算机上运行时，使得计算机执行第三方面所述的方法。
第九方面，提供了一种光模块，包括第一方面中任一设计所述的光发射机，以及光接收 机。
第十方面，提供了一种光通信设备，包括第九方面所述的光模块，以及处理电路；所述处理电路用于向所述光模块提供携带待传输数据的驱动信号，所述光模块中的调制单元用于基于所述驱动信号对光进行调制。
第十一方面，提供了一种光通信系统，包括多个第十方面所述的光通信设备。
第二方面至第十一方面的效果可以参考第一方面中相应方案的效果，本申请在此不做赘述。
附图说明
图1为本申请实施例提供的一种光通信系统的结构示意图；
图2为本申请实施例提供的另一种光通信系统的结构示意图；
图3为本申请实施例提供的一种光发射机的结构示意图；
图4为本申请实施例提供的另一种光发射机的结构示意图；
图5为本申请实施例提供的又一种光发射机的结构示意图；
图6为本申请实施例提供的一种通信网络的示意图；
图7为本申请实施例提供的一种光通信系统的示意图；
图8为本申请实施例提供的一种光发射机的结构示意图；
图9为本申请实施例提供的一种光源发出的光的功率示意图；
图10为本申请实施例提供的一种第一波长的滤波示意图；
图11为本申请实施例提供的一种第二波长的滤波示意图；
图12为本申请实施例提供的一种MRM的频谱示意图；
图13为本申请实施例提供的一种非等臂MZM的频谱示意图；
图14为本申请实施例提供的一种开关单元的结构示意图；
图15为本申请实施例提供的另一种开关单元的结构示意图；
图16为本申请实施例提供的另一种开关单元的结构示意图；
图17为本申请实施例提供的另一种开关单元的结构示意图；
图18为本申请实施例提供的另一种开关单元的结构示意图；
图19为本申请实施例提供的一种调制单元的结构示意图；
图20为本申请实施例提供的另一种调制单元的结构示意图；
图21为本申请实施例提供的一种信号的星座图；
图22为本申请实施例提供的另一种信号的星座图；
图23为本申请实施例提供的另一种信号的星座图；
图24为本申请实施例提供的另一种调制单元的结构示意图；
图25为本申请实施例提供的另一种调制单元的结构示意图；
图26为本申请实施例提供的另一种调制单元的结构示意图；
图27为本申请实施例提供的另一种调制单元的结构示意图；
图28为本申请实施例提供的另一种调制单元的结构示意图；
图29为本申请实施例提供的另一种调制单元的结构示意图；
图30为本申请实施例提供的一种光发射方法的流程图；
图31为本申请实施例提供的一种开关控制方法的流程图；
图32为本申请实施例提供的一种开关控制装置的结构示意图。
具体实施方式
为使本申请的原理、技术方案和优点更加清楚，下面将结合附图对本申请实施方式做进一步的详细描述。
本申请实施例提供了一种光通信系统，该光通信系统包括多个光通信设备。光通信设备之间具有链路，光通信设备之间可以通过在链路上传输的光信号通信。
光通信设备可以是通过光信号进行通信的任意设备，如光线路终端(optical line terminal，OLT)、光传送网(optical transport network，OTN)设备、数据中心等。
传输光信号的链路可以包括光纤，该链路还可以包括设置在光纤上的一个或多个器件，如光功率放大器(booster amplifier，BA)、光线路放大器(optical line amplifier，OLA)、前置放大器(pre-amplifier，PA)。链路中的部分链路段还可以通过设置光检测通道(optical supervisory channel，OSC)实现对光信号的波长和光功率等参数的检测。
示例地，图1为本申请实施例提供的一种光通信系统的结构示意图。图1中示出了第一光通信设备01和第二光通信设备02，以及第一光通信设备01和第二光通信设备02之间的链路。链路包括光纤03，以及设置在光纤03上且沿第一光通信设备01到第二光通信设备01的方向依次排布的BA 04、OLA 05、PA 06，且部分链路段设置了OSC。
光通信设备包括光模块，光模块包括光发射机(transmitter，Tx)和光接收机(receiver，Rx)，光发射机用于调制光通信设备待发射的光信号，光接收机用于解调光通信设备接收到的光信号。图1中以光通信设备01向光通信设备02发送光信号为例。请继续参考图1，第一光通信设备01中的光模块(图1中未示出)包括光发射机011，第二光通信设备02中的光模块(图1中未示出)包括光接收机021。其中，光发射机011能够调制光信号，并将该光信号通过链路传输至第二光通信设备02的光接收机021。第二光通信设备02中的光接收机021可以对该光信号进行解调。
光通信设备除了包括光模块之外，还可以包括其他结构，比如，光通信设备还包括处理电路；该处理电路用于向光模块提供携带待传输数据的驱动信号，光模块中的调制单元用于基于该驱动信号对光进行调制得到光信号。
随着数据业务爆炸式增长，光通信系统快速发展，光通信设备中光发射机的数量也可以是多个，光通信设备中光接收机的数量也可以是多个。这种情况下，该光通信系统可以是基于波分复用(wavelength division multiplexing，WDM)系统，如密集波分复用(dense wavelength division multiplexing，DWDM)系统。
比如，如图2所示，在图1的基础上，第一光通信设备01中的光模块包括三个光发射机011和MUX，第二光通信设备02中的光模块包括三个光接收机021和DEMUX。第一光通信设备01中的各个光发射机011通过MUX连接至链路，第二光通信设备02中各个第二光接收机021通过DEMUX连接至链路。光发射机011用于发出一种波长的光信号，并且不同光发射机011发出的光信号的波长不同；不同光接收机021用于接收一种波长的光信号，并且不同光接收机021接收到的光信号的波长也不同。
进一步地，光发射机可以有多种实现方式。
示例地，如图3所示，光发射机可以包括光源0111和调制单元0112。其中，光源0111用于提供一个波长的光，调制单元0112用于对该光进行调制，得到该一个波长的光信号。
又示例地，如图4所示，光发射机可以包括光源0111、调制单元0112和光波长转换单元(optical transponder unit，OTU)0113。其中，光源0111用于提供一个波长的光；调制单元0112用于对该光进行调制，得到该一个波长的光信号；OTU 0113用于对该光信号进行波长转换，得到另一个波长的光信号。
OTU也可以有多种实现方式。
比如，请继续参考图4，OTU 0113包括泵浦光源01131A和非线性器件01132A。非线性器件01132A包括非线性材料(如氮化硅、铌酸锂等)，非线性器件01132A可以是氮化硅微环、薄膜铌酸锂波导等。其中，泵浦光源01131A用于向非线性器件01132A提供泵浦激光，调制单元0112调制得到的一个波长的光信号会传输至非线性器件01132A，在泵浦激光的作用下，该一个波长的光信号能够在非线性器件01132A中转换为另一个波长的光信号，实现光信号的波长转换。但是，光信号在非线性器件01132A中的转换效率低，转换得到的光信号的功率较小，影响光信号的质量。并且，光信号在经过非线性器件的过程中会引入噪声，导致光信号劣化，有OSNR代价，影响通信效果。
又比如，请参考图5，OTU 0113采用光电光的方式切换光信号的波长。OTU 0113包括光电二极管(photo-diode，PD)01131B和直调光模块01132B。其中，调制单元0112调制得到的一个波长的光信号会传输至PD 01131B，并被PD 01131B解调为电信号后传输至直调光模块01132B，直调光模块01132B包括另一光源和另一调制单元(图5中未示出)，直调光模块01132B的光源提供与光源0111不同波长的光，因此可以由直调光模块01132B中的调制单元根据该电信号调制得到另一个波长的光信号，实现光信号的波长转换。但是，由于PD 01131B只能对光信号的功率进行解调，无法对光信号的相位进行解调，因此PD 01131B只能将直接调制光信号转换为电信号，而无法实现将同向正交光信号(相干光信号)转换为电信号。所以，图5所示的OTU 0113所在的光发射机无法输出同向正交光信号。并且，当光发射机需要输出多种波长的光信号(如图2所示)时，该光发射机需要包括多个光源、多个调制单元、多个PD和多个直调光模块，可见，该光发射机中器件的数量较多，光发射机的成本和功耗都较高。此外，在直调光模块的调制方式比较复杂(例如采用四电平脉冲幅度调制)时，对光发射机中各个器件的性能要求较高，比如，要求PD需要较好地响应系数和灵敏度，调制单元需要较高的消光比和线性度等，否则会存在引入噪声或光信号携带的信息丢失的问题。
进一步地，光通信设备存在切换发送的光信号的波长的情况。
示例地，假设第一光通信设备01和第二光通信设备02之间的通信网络如图6所示，第一光通信设备01和第二光通信设备02之间可以存在链路A(节点1→节点2→节点3→节点7)和链路B(节点1→节点4→节点7)。假设第一光通信设备01通过链路A向第二光通信设备02发送波长1的光信号，若在此过程中链路A故障，则第一光通信设备01可以通过重路由确定链路B，并通过链路B向第二光通信设备01发送光信号。在链路B中，若第一光通信设备01原先发送的光信号的波长1已经被占用，则第一光通信设备01还需要切换光信号的波长，比如，第一光通信设备01将原先光信号的波长1切换为未被占用的波长2。
又示例地，如图7所示，假设光通信系统包括8个光通信设备A至H，其中，光通信设 备A可以向光通信设备E和F发送光信号，光通信设备B可以向光通信设备G发送光信号，光通信设备C可以向光通信设备G和H发送光信号，光通信设备D可以向光通信设备H发送光信号。光通信设备E至H可以对接收到的光信号进行处理。假设光通信设备C为第一光通信设备，光通信设备C在向光通信设备G发送光信号的过程中，若光通信设备G的负载较高，且光通信设备H的负载较低，则光通信设备C可以停止向光通信设备G发送光信号，并切换为向光通信设备H发送光信号。若此时光通信设备C发送的光信号的波长与光通信设备D向光通信设备H发送光信号的波长相同，则光通信设备C需要切换向光通信设备H发送的光信号的波长。
光通信设备利用光发射机切换光信号的波长。但是，目前，光发射机切换光信号的波长的过程较繁琐，且速度较慢。
比如，对于如图3所示的光发射机，在光通信设备切换发送的光信号的波长时，光发射机中的光源0111切换向调制单元0112提供的光的波长。另外，调制单元0112在调制光得到光信号时，需要加载偏置电压和携带数据的电信号(也称驱动信号，该驱动信号可以由光通信设备中的处理电路提供)，且不同偏置电压下调制单元0112对相同波长的光的调制效果不同。所以，在光源0111切换光的波长后，为了实现对该光的有效调制，光发射机还需要根据切换后的光的波长对调制单元0112的偏置电压进行调整。但是，光源0111切换光的波长需要几秒，光发射机调整调制单元0112的偏置电压需要十几秒或几十秒，这样一来，就使得光发射机切换光信号的波长共需要十几秒或几十秒。而为了保证通信的稳定，要求光发射机切换发送的光信号的波长的时间需控制在50毫秒以内。可见，图3所示的光发射机无法满足这一要求，会造成业务长时间的中断，影响了通信的稳定和连续性。
又比如，对于如图4所示的光发射机，在光通信设备切换发送的光信号的波长时，光发射机中的泵浦光源01131A切换泵浦激光的波长，以使光发射机中的非线性器件01132A输出的光信号的波长改变。但是，泵浦光源01131A切换泵浦激光的波长需要几秒，这样一来，就使得光发射机切换光信号的波长共需要几秒。而为了保证通信的稳定，要求光发射机切换光信号的波长的时间需控制在50毫秒以内。可见，图4所示的光发射机也无法满足这一要求，会造成业务长时间的中断，影响了通信的稳定和连续性。
再比如，对于如图5所示的光发射机，在光通信设备切换发送的光信号的波长时，光发射机中的直调光模块01132B中的光源切换向直调光模块01132B中的调制单元提供的光的波长。另外，光发射机还需要根据该波长对直调光模块01132B中的调制单元的偏置电压进行调整。但是，直调光模块01132B中的光源切换光的波长需要几秒，光发射机调整直调光模块01132B中的调制单元的偏置电压需要十几秒或几十秒，这样一来，就使得光发射机切换发送的光信号的波长共需要十几秒或几十秒。而为了保证通信的稳定，要求光发射机切换发送的光信号的波长的时间需控制在50毫秒以内。可见，图5所示的光发射机也无法满足这一要求，会造成业务长时间的中断，影响了通信的稳定和连续性。
本申请实施例提供了一种光发射机，该光发射机切换光信号的波长的过程较为简单，且切换光信号的波长的速度较快，能够将切换光信号的波长的时间控制在50毫秒以内。并且，本申请实施例提供的光发射机还可以调制得到同向正交光信号。
示例地，图8为本申请实施例提供的一种光发射机的结构示意图，如图8所示，该光发 射机包括：光源101、开关单元102、调制单元103和控制单元104。其中，光源101、开关单元102和调制单元103依次连接，控制单元104与开关单元102连接。
光源101用于向开关单元102提供多个波长的光(也称连续光)。该多个波长可以是匹配国际电信联盟(international telecommunication union，ITU)标准的波长，如匹配ITU DWDM标准的波长。该多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍，第一波长和第二波长之差的绝对值是该调制单元的FSR的正整数倍。比如，第一波长和第二波长之差为该调制单元的FSR的整数倍。
控制单元104用于在第一时间段内控制开关单元102向调制单元103输出第一波长的光，以及在第二时间段内控制开关单元102向调制单元103输出第二波长的光。
调制单元103用于在第一时间段内对开关单元102输入的第一波长的光进行调制，以输出第一波长的调制光，以及在第二时间段内对开关单元102输入的第二波长的光进行调制，以输出第二波长的调制光。
调制单元103在波长差为FSR的整数倍的任意两个波长处的频谱响应相同(或近似相同)。由于多个波长中第一波长和第二波长之差为调制单元的FSR的整数倍，因此，调制单元103对第一波长和第二波长的光的调制效果相同(或近似相同)，比如调制单元在第一波长和第二波长处调制的消光比、带宽、误码率等性能都是一致的。在光发射机需要切换光信号的波长时，开关单元102输入调制单元103的光的波长可以在第一波长和第二波长之间切换，但调制单元103对波长切换前后的光的调制效果相同(或近似相同)，因此，无需改变调制单元103上加载的偏置电压。
另外，调制单元103上加载的驱动信号与业务相关，在业务不变时，驱动信号携带的数据不变，调制单元103加载的驱动信号也不变；在业务改变时，驱动信号携带的数据改变，调制单元103加载的驱动信号也改变。
综上所述，本申请实施例提供的光发射机中，光源能够向开关单元提供多个波长的光，并且，控制单元能够控制开关单元向调制单元输出该多个波长中第一波长或第二波长的光，以便于调制单元对接收到的光进行调制。由于第一波长和第二波长之差为调制单元的FSR的整数倍，且开关单元输入调制单元的光的波长能够在第一波长和第二波长之间切换，因此，在光发射机需要将光信号的波长在第一波长和第二波长之间切换时，调制单元无需改变偏置电压，光源也无需改变提供的光，只需控制单元控制开关单元输出切换后的波长的光即可。可见，该光发射机切换光信号的波长的过程较为简单。
通常控制单元控制开关单元切换输出的光的波长的速度较快，因此，光发射机切换光信号的波长的速度也较快，光发射机所在的光通信设备切换发出的光信号的波长的速度也较快。本申请提供的光发射机切换光信号的波长的时间能够控制在50毫秒以内，能够实现业务的“无缝衔接”，不影响业务的连续性和一致性。示例地，在上述开关单元为基于热光效应的开关单元(可以称为热光开关)时，光发射机切换光信号的波长所需的时长为毫秒级时长；在上述开关单元为基于电光效应的开关单元(可以称为电光开关)时，光发射机切换光信号的波长所需的时长为纳秒级时长。相比前述相关技术中光发射机切换光信号的波长需要几十秒的时长，本申请实施例提供的光发射机切换光信号的波长的时长降低了千倍甚至百万倍。
以上实施例中以光发射机包括一个调制单元103为例，可以理解的是，光发射机也可以包括多个调制单元103；不同调制单元103的FSR可以相同也可以不同。在光发射机包括多 个调制单元103时，上述多个波长包括：该多个调制单元103一一对应的多个波长组。对于一个调制单元103对应的波长组，该波长组包括第一波长和第二波长，且第一波长和第二波长之差为该调制单元103的FSR的整数倍。不同波长组可以相同也可以不同，不同波长组中的第一波长不同，不同波长组中的第二波长不同。这种情况下，控制单元104用于：在第一时间段内控制开关单元102向调制单元103输出对应的波长组中第一波长的光，以及在第二时间段内控制开关单元102向调制单元103输出对应的波长组中第二波长的光。
本申请实施例不对上述多个波长组中波长的大小关系进行限定。示例地，该多个波长组可以按照从小到大的顺序依次排布，这种情况下，存在一个波长组中的最小波长大于另一个波长组中的最大波长的情况。又示例地，也可以是该多个波长组存在交叉，这种情况下，存在一个波长组中的一些波长大于另一个波长组中的一些波长，但小于该另一个波长组中的另一些波长的情况。
根据以上内容可知，本申请实施例提供的光发射机包括：光源101、开关单元102、至少一个调制单元103和控制单元104。光源101用于向开关单元102提供与至少一个调制单元103一一对应的至少一个波长组的光，其中，每个波长组包括第一波长和第二波长，第一波长和第二波长之差为该波长组对应的调制单元103的FSR的整数倍。控制单元104用于在第一时间段内控制开关单元102向每个调制单元103输出该调制单元103对应的波长组中第一波长的光，以及在第二时间段内控制开关单元102向每个调制单元103输出该调制单元103对应的波长组中第二波长的光。每个调制单元103用于在第一时间段内对开关单元102输入的该调制单元103对应的波长组中第一波长的光进行调制，以输出该第一波长的调制光。每个调制单元103还用于在第二时间段内对开关单元102输入的该调制单元103对应的波长组中第二波长的光进行调制，以输出该第二波长的调制光。
可以理解的是，每个波长组除了包括第一波长和第二波长之外，可以不包括其他波长，也可以还包括其他波长，本申请实施例对此不作限定。并且，在波长组包括该其他波长时，波长组中任意两个波长之差均可以是该波长组对应的调制单元的FSR的整数倍。示例地，波长组中按照从小到大的顺序排布的第i个波长与第i+1个波长之差为FSR，i≥1，换句话说，该波长组中的波长按照FSR的间隔依次排布。假设该波长组中最小的波长为X，且该波长组包括5个波长，则这5个波长分别为X、X+FSR、X+2*FSR、X+3*FSR和X+4*FSR。
另外，本申请实施例中以光信号的波长在第一波长和第二波长之间切换，且光信号的波长只切换一次为例。可以理解的是，在波长组还包括除第一波长和第二波长之外的其他波长时，光信号的波长可以在波长组中任意两个波长之间切换，并且，光信号的波长可以在波长组中多次切换。
本申请实施例中，开关单元102可以看作是一个滤波器。开关单元102对每个调制单元103对应的波长组的光的滤波间隔大于该波长组的波长范围，这样一来，开关单元102便可以从该波长组的光中选择一个波长的光输出至该波长组对应的调制单元。
示例地，假设一个波长组包括λ1至λn，n大于1，那么光源101输出的这些波长的光的功率可以如图9所示，可以看出，这些波长的光的功率相同(或相似)，且均大于零。如图10所示，在第一时间段，开关单元102能够在控制单元104提供的控制电信号(电压信号或电流信号)的控制下，使该波长组中第一波长λa的滤波响应为“1”，以使开关单元102输出的该第一波长λa的光的功率大于零，进而该波长组对应的调制单元103能够对第一波 长λa的光进行调制，以输出第一波长λa的光信号。在第一时间段，开关单元102还能够在控制单元104提供的控制电信号的控制下，使该波长组中除第一波长λa之外的其他波长的滤波响应为“0”，以使开关单元102输出的该其他波长的光的功率为零。
当光信号的波长在该波长组中的波长之间切换时，只需改变控制单元104向开关单元102提供的控制电信号即可。示例地，如图11所示，假设在第二时间段，光信号的波长需要由图10中λ1至λn中的第一波长λa切换为第二波长λb，那么，控制单元104在第二时间段相对在第一时间段向开关单元102提供的控制电信号发生改变。在第二时间段，开关单元102能够在控制单元104提供的控制电信号的控制下，使该波长组中第二波长λb的滤波响应为“1”，以使开关单元102输出的第二波长λb的光的功率大于零，进而该波长组对应的调制单元103能够对第二波长λb的光进行调制，以输出第二波长λb的光信号。在第二时间段，开关单元102还能够在控制单元104提供的控制电信号的控制下，使该波长组中除第二波长λb之外的其他波长的滤波响应为“0”，以使开关单元102输出的该其他波长的光的功率为零。
在本申请实施例中，调制单元103是具有FSR的调制器，比如调制单元103可以是谐振型调制器(如微环调制器(micro-ring modulator，MRM))或干涉型调制器(如非等臂MZM)、迈克尔逊干涉调制器(michelson interferometric modulator，MIM))等。
调制单元103的FSR为调制单元103的频谱中两个相邻响应之间的波长差。
示例地，在调制单元103为谐振型调制器时，谐振型调制器的两个相邻谐振波长之间的差值即为该谐振型调制器的FSR。以谐振型调制器为MRM为例，假设MRM用于对C波段(1529.16纳米至1568.36纳米，191.15太赫兹(THz)至196.05太赫兹))的光进行调制，且该MRM包括半径为100微米的硅光波导，该MRM的频谱如图12所示，该MRM共有6个谐振波长，分别为1543.181纳米、1544.681纳米、1546.183纳米、1547.688纳米、1549.197纳米、1550.708纳米，则该MRM的FSR约为1.505纳米。
又示例地，在调制单元103为干涉型谐振器时，干涉型谐振器的两个相邻干涉相消波长之差或两个相邻干涉相长波长之差即为该干涉型谐振器的FSR。以干涉型谐振器为非等臂MZM为例，假设非等臂MZM用于对C波段的光进行调制，且该非等臂MZM包括两个波导臂，这两个波导臂均包括硅光波导，这两个波导臂的长度差为128微米。该非等臂MZM的频谱如图13所示，该非等臂MZM共有3个干涉相消波长，分别为1545.32纳米、1550.14纳米、1554.98纳米，则非等臂MZM的FSR约为4.83纳米。
此外，调制单元的FSR与调制单元的几何参数有关。比如，在调制单元是MRM时，调制单元的FSR＝λ 2/(2πR·n g)，其中，λ为调制单元对应的波长组中的任一波长(如中心波长)，π表示圆周率，R为MRM中微环的半径，n g为MRM的微环中波导的群折射率。在调制单元是非等臂MZM或非等臂MIM时，调制单元的FSR＝λ 2/(ΔL·n g)，其中ΔL为非等臂MZM或非等臂MIM的两个波导臂的长度差。可以根据需要设置调制单元对应的波长组，相应地设计光源发出的光的波长、开关单元的几何参数和调制单元的几何参数，以使调制单元的FSR与光源发出的光的波长匹配(光源发出的每个调制单元对应的波长组中任意两个波长的光的波长之差是该调制单元的FSR的整数倍)。例如，若调制单元对应的波长组需要匹配ITU DWDM标准，且该调制单元对应的波长组中相邻波长的间隔需要设置为100吉赫兹(GHz)时，光源需要发出满足这一条件的该多个波长，开关单元和调制单元的结构和功能也需要相 应设计。可见，本申请实施例提供的光发射机的灵活度较高，可以适配各种通信标准。
以下将分别以包括一个调制单元和包括多个调制单元的光发射机为例进行讲解。
示例1，光发射机包括一个调制单元103。该光发射机中光源101用于输出该调制单元103对应的波长组(包括波长1至20)的光。若在第一时间段内，波长1至20中的波长5是第一波长，那么开关单元102可以在控制单元104的控制下，将波长5的光输出至调制单元103，以及禁止输出波长1-4的光，以及波长6-20的光。调制单元103对该波长5的光进行调制，以使光发射机输出波长5的光信号。若在第二时间段内，波长1至20中的波长7是第二波长，那么开关单元102可以在控制单元104的控制下，将波长7的光输出至调制单元103，以及禁止输出波长1-6的光，以及波长8-20的光。调制单元103对该波长7的光进行调制，以使光发射机输出波长7的光信号。这样一来，便实现了将光发射机输出的光信号的波长由波长5切换为波长7。在此过程中，光源101持续发出多个波长的光，调制单元103上加载的偏置电压无需改变。
示例2，光发射机包括四个调制单元103。该光发射机中光源101用于输出波长1至50的光，其中，第一个调制单元103对应的波长组包括：波长1、5...49；第二个调制单元103对应的波长组包括：波长2、6...50；第三个调制单元103对应的波长组包括：波长3、7...47；第四个调制单元103对应的波长组包括：波长4、8...48。假设在第一时间段，波长1、5...49中的波长5是第一波长，波长2、6...50中的波长6是第一波长，波长3、7...47中的波长7是第一波长，波长4、8...48中的波长8是第一波长。那么，开关单元102可以在控制单元104的控制下，将波长5、6、7、8的光输出，以及禁止输出波长1-4的光，以及波长9-50的光。第一个调制单元103能够对该波长5的光进行调制，第二个调制单元103能够对该波长6的光进行调制，第三个调制单元103能够对该波长7的光进行调制，第四个调制单元103能够对该波长8的光进行调制，以使光发射机输出波长5、6、7、8的光信号。在第二时间段，若任一调制单元103对应的波长组中的第一波长切换为第二波长，那么开关单元102可以在控制单元104的控制下，将输出的光的波长由该第一波长切换为该第二波长，以使该调制单元103对该第二波长的光进行调制。在此过程中，光源101持续发出多个波长的光，该调制单元103上加载的偏置电压无需改变。
可以理解的是，不同调制单元103对应的波长组中波长的个数可以相同也可以不同。在光发射机包括多个调制单元103时，可以是一个或多个调制单元103对应的波长组中的波长发生切换。并且，不同调制单元103用于调制得到的光信号的波长在切换前后的波长差可以相同也可以不同，本申请实施例对此不作限定。
在光发射机包括多个调制单元103时，光发射机的调制速度为该多个调制单元103的调制速度之和。比如，假设每个调制单元103的调制速度均为100吉比特每秒(Gb/s)，且光发射机包括四个调制单元103，那么光发射机的调制速度为400吉比特每秒。
进一步地，光源101、开关单元102和调制单元103均可以有多种可实现方式，以下将分别对光源101、开关单元102和调制单元103中每个部分的多种可实现方式进行介绍。
(1)光源101。
(1.1)在光源101的第一种可实现方式中，光源101可以包括QDMLL或QWMLL。示例地，QDMLL和QWMLL均可以发出在1540纳米至1560纳米的范围内的50个波长的光，并且这50个波长中相邻波长的间隔为0.4纳米，相邻波长对应的频率的间隔为间隔50吉赫 兹，这些波长可以匹配ITU，比如匹配ITU DWDM标准。
(1.2)在光源101的第二种可实现方式中，光源101可以是光频梳。光频梳能够发出一定波长范围内不同重频(例如频率间隔为50吉赫兹、100吉赫兹等)的多个波长的光。
(1.3)在光源101的第三种可实现方式中，光源101可以是光源池。光源池包括与上述多个波长一一对应的多个激光器，以及MUX，每个激光器用于发出对应的波长的光，MUX用于将该多个激光器发出的多个波长的光进行合波。
(2)开关单元102。
开关单元102可以具有一个出端口，开关单元102用于从该出端口向每个调制单元103输出光。比如，在第一时间段，开关单元102用于从该出端口向每个调制单元103输出该调制单元103对应的波长组中第一波长的光。在第二时间段，开关单元102用于从该出端口向每个调制单元103输出该调制单元103对应的波长组中第二波长的光。这种情况适用于光发射机包括一个或多个调制单元103的情况。
或者，在光发射机包括多个调制单元103时，开关单元102具有与该多个调制单元103一一对应的多个出端口，开关单元102用于从调制单元103对应的出端口向该调制单元输出光。比如，在第一时间段，开关单元102用于从调制单元103对应的出端口向该调制单元103输出该调制单元103对应的波长组中第一波长的光。在第二时间段，开关单元102用于从调制单元103对应的出端口向该调制单元103输出该调制单元103对应的波长组中第二波长的光。
(2.1)在开关单元102的第一种可实现方式中，开关单元102具有一个出端口，这种情况适用于光发射机包括一个或多个调制单元103的情况。开关单元102的第一种可实现方式可以与光源101的每种可实现方式结合。
如图14所示，开关单元102包括：第一DEMUX和第一MUX，以及调制单元103对应的光开关组。光发射机包括至少一个调制单元103，因此，开关单元102就包括与该至少一个调制单元103一一对应的至少一个光开关组。图14中仅示出了一个调制单元103对应的一个光开关组，在光发射机包括多个调制单元103时，开关单元102包括多个光开关组(如在光发射机包括两个调制单元103时，图15中开关单元102包括两个光开关组)。开关单元102的一个出端口为第一MUX的出端口。
请继续参考图14或图15，以一个调制单元103(至少一个调制单元103中的任一调制单元103)，该调制单元103对应的波长组和开关组为例：第一DEMUX用于接收该波长组的光；该光开关组包括：与该波长组中的各个波长一一对应的多个光开关；该多个光开关可以相同也可以不同。第一DEMUX用于将接收到的该波长组中各个波长的光分别传输至该各个波长对应的光开关。在第一时间段，控制单元(图14和图15中未示出)用于控制该光开关组中对应第一波长的光开关导通，以及控制该光开关组中不对应第一波长的光开关关断；这样一来，该波长组中第一波长的光传输至第一MUX后输出至该调制单元103，而该波长组中除第一波长之外的其他波长的光无法传输至第一MUX并输出至该调制单元103。在第二时间段，控制单元(图14和图15中未示出)用于控制该光开关组中对应第二波长的光开关导通，以及控制该光开关组中不对应第二波长的光开关关断；这样一来，该波长组中第二波长的光传输至第一MUX后输出至该调制单元103，而该波长组中除第二波长之外的其他波长的光无法传输至第一MUX并输出至该调制单元103。
总的来说，在光发射机包括至少一个调制单元103时，第一DEMUX用于接收该至少一个调制单元103中每个调制单元对应的波长组的光；第一DEMUX用于将接收到的这些波长的光分别传输至波长对应的光开关，不同波长对应的光开关不同。在第一时间段，控制单元用于控制每个调制单元103对应的光开关组中对应第一波长的光开关导通，以及控制该光开关组中不对应第一波长的光开关关断；这样一来，每个调制单元103对应的光开关组中第一波长的光传输至第一MUX后输出至该调制单元。在第二时间段，控制单元用于控制每个调制单元103对应的光开关组中对应第二波长的光开关导通，以及控制该光开关组中不对应第二波长的光开关关断；这样一来，每个调制单元103对应的光开关组中第二波长的光传输至第一MUX后输出至该调制单元。
在开关单元102的第一种可实现方式中，第一DEMUX具有与光源101连接的输入端，第一DEMUX具有与上述至少一个调制单元103对应的光开关组中光开关一一对应连接的多个输出端。第一MUX具有与上述至少一个调制单元103对应的光开关组中光开关一一对应连接的多个输入端，以及与上述至少一个调制单元103连接的输出端。光开关与控制单元连接，控制单元可以确定光开关组中需要开启的光开关，以及需要关断的光开关。控制单元可以向需要开启的光开关提供用于开启光开关的控制电信号，以及向需要关断的光开关提供用于关断光开关的控制电信号。可以理解的是，需要关断的光开关也可以是默认处于关断状态，控制单元也可以无需向这些光开关提供控制电信号。
示例地，假设一个调制单元103对应的波长组包括20个波长，这20个波长中最小波长为该调制单元103当前需要调制得到的光信号的波长(如第一时间段的第一波长或第二时间段的第二波长)，则控制单元可以控制这20个波长一一对应的20个光开关中，对应该最小波长的光开关开启，以及这20个光开关中除该光开关之外的其他光开关关断。这样一来，便可以使得开关单元输出这20个波长的光中最小波长的光。
(2.2)在开关单元102的第二种可实现方式中，开关单元102具有一个出端口，这种情况适用于光发射机包括一个或多个调制单元103的情况。开关单元102的第二种可实现方式可以与光源101的每种可实现方式结合。
如图16所示，开关单元102包括：第一光波导和第二光波导，以及调制单元103对应的微环组。光发射机包括至少一个调制单元103，因此，开关单元102包括与该至少一个调制单元103一一对应的至少一个微环组，图16中以一个调制单元103对应的一个微环组为例，图17中以多个调制单元103一一对应的多个微环组为例。开关单元102的一个出端口为第二光波导的一端。
请参考图16或图17，第一光波导和第二光波导均呈条状，且延伸方向相同；微环组包括：沿第一光波导和第二光波导的排布方向，依次间隔地排布在第一光波导和第二光波导之间的至少两个开关微环，图16和图17中均以微环组包括两个开关微环(开关微环也称微环谐振器)为例；图17中以各个微环组相同为例，可以理解的是，各个微环组中开关微环的尺寸和数量也可以不同。第一光波导耦合微环组中与第一光波导相邻的开关微环，第二光波导耦合微环组中与第二光波导相邻的开关微环，微环组中相邻的开关微环之间互相耦合。比如，图16和图17中每个微环组中的两个开关微环相互耦合，并且，上面的开关微环与第二光波导耦合，下面的开关微环与第一光波导耦合。在每个微环组中的至少两个开关微环中，不同所述开关微环的半径不同。在至少一个微环组包括多个微环组时，多个微环组沿第一光波导 的延伸方向依次间隔排布。
可以理解的是，第一光波导和第二光波导还可以有其他实现方式，比如，第一光波导和第二光波导的延伸方向可以不同(如垂直)。在第一光波导和第二光波导的延伸方向相互垂直时，微环组也可以只包括位于第一光波导和第二光波导之间的一个开关微环，这个开关微环可以与第一光波导和第二光波导均耦合。
无论第一光波导、第二光波导和微环组采用何种实现方式，以一个调制单元103(至少一个调制单元103中的任一调制单元103)及其对应的波长组和微环组为例：第一光波导用于接收光源101发出的该调制单元103对应的波长组的光；控制单元可以与每个开关微环连接，控制单元用于在第一时间段控制该微环组将第一光波导中传输的该波长组的光中第一波长的光耦合至第二光波导后输出至该调制单元103，以及在第二时间段控制该微环组将第一光波导中传输的该波长组的光中第二波长的光耦合至第二光波导后输出至该调制单元103。
总的来说，在光发射机包括至少一个调制单元103时，第一光波导用于接收光源101发出的该至少一个调制单元103中每个调制单元103对应的波长组的光；控制单元可以与每个微环组连接，控制单元用于控制每个调制单元103对应的微环组将第一光波导中传输的该调制单元对应的波长组的光中一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光耦合至第二光波导后输出。
在开关单元102的第二种可实现方式中，第一光波导具有与光源101连接的一端，第二光波导具有与调制单元103连接的一端。控制单元与每个微环组电连接，控制单元可以根据该微环组的尺寸，以及该微环组对应的调制单元103待调制得到的光信号的波长，向微环组中的开关微环提供控制电信号，以使该微环组能够将该波长的光信号从第一光波导耦合至第二光波导。示例地，开关微环包括环状光波导，以及位于环状光波导周围的电极，图16和图17中仅示出了开关微环中的环状光波导。控制单元可以与该电极连接，用于向微环组中的各个电极加载控制电信号(电流信号或电压信号)，使微环组能够将该第一光波导中传输的该波长的光耦合至第二光波导。
在微环组包括沿第一光波导和第二光波导的排布方向，依次间隔地排布在第一光波导和第二光波导之间的至少两个开关微环时(如图16或图17所示)，微环组可以在控制单元提供的控制电信号的控制下，基于游标卡尺效应将第一光波导上传输的该调制单元103对应的波长组的光中，一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光耦合至第二光波导。示例地，微环组中的每个开关微环能够在控制单元提供的控制电信号的控制下，从第一光波导中耦合该波长组的光中一个波长集合的光；不同开关微环能够在控制单元提供的控制电信号的控制下，从第一光波导中耦合不同波长集合的光，并且，该微环组中的至少两个开关微环在控制电信号的控制下耦合的至少两个波长集合均包含上述一个波长，该至少两个开关微环基于游标卡尺效应，便可以将该一个波长的光耦合至第二光波导。
开关微环的半径与开关微环从第一光波导中耦合的光的波长的间隔相关，半径较大的开关微环从第一光波导中耦合的光的波长的间隔较小，而半径较小的开关微环从第一光波导中耦合的光的波长的间隔较大。微环组中不同开关微环的半径不同，因此，不同开关微环从第一光波导中耦合的光的波长的间隔不同，使得不同开关微环从第一光波导中耦合不同波长组的光。
如果需要改变微环组耦合至第二光波导的光的波长，则可以改变控制单元向该微环组中 至少一个开关微环提供的控制电信号。其中，控制单元向开关微环加载的控制电信号改变时，开关微环从第一光波导中耦合的光的波长改变，但开关微环从第一光波导中耦合的光的波长的间隔不变。
例如，假设调制单元103对应波长组包括(波长1-20)，调制单元103对应的微环组包括两个开关微环。如果半径较大的一个开关微环能够在控制单元提供的控制电信号的控制下，从第一光波导中耦合波长1、5、9、13和17的光，半径较小的开关微环能够在控制单元提供的控制电信号的控制下，从第一光波导中耦合波长2、9和16的光，那么，该微环组便可以将波长9的光耦合至第二光波导。
如果需要改变耦合至第二光波导的光的波长，可以改变控制单元向半径较大的一个开关微环提供的控制电信号，以使半径较大的该开关微环从第一光波导中耦合波长2、6、10、14和18的光，这样一来，该微环组便可以在控制单元的控制下将波长2的光耦合至第二光波导。或者，如果需要改变耦合至第二光波导的光的波长，可以改变控制单元向半径较小的一个开关微环提供的控制电信号，以使半径较小的该开关微环从第一光波导中耦合波长3、10和17的光，这样一来，该微环组便可以将波长17的光耦合至第二光波导。
开关单元102可以看做滤波器，在开关单元102的第二种可实现方式中，开关单元102利用微环组进行滤波，微环组的滤波间隔需要大于光源101提供的多个波长所在的波长范围，这样一来，微环组便可以输出该多个波长中的一个波长的光。微环组的滤波间隔为微环组中各个开关微环的滤波间隔的最小公倍数，因此，可以根据需要的微环组的滤波间隔设置微环组中开关微环的滤波间隔。
以微环组包括半径不同的两个开关微环为例。假设光源101向开关单元提供调制单元103对应的波长组均属于C波段，且匹配ITU DWDM标准。该波长组可以是在1529.16纳米至1568.36纳米(即191.15太赫兹至196.05太赫兹，约为4.9太赫兹)的范围内按照50吉赫兹的间隔依次排布的50个波长。开关微环的FSR＝λ 2/(2πR·n g)，假设开关微环中波导的群折射率n g为4，则可以将两个开关微环中的较大半径设置为480微米左右，将较小半径设置为9微米左右。这样一来，该较大半径的开关微环的滤波间隔为25吉赫兹(即0.2纳米)，该较小半径的开关微环的滤波间隔为1.28太赫兹(即10.24纳米)，该微环组的滤波间隔为6.4太赫兹(大于4.9太赫兹)。
(2.3)在开关单元102的第三种可实现方式中，开关单元102具有多个出端口，这种情况适用于光发射机包括多个调制单元103的情况。开关单元102的第三种可实现方式可以与光源101的每种可实现方式结合。
如图18所示，开关单元102包括：第一光波导，与多个调制单元103一一对应的多个微环组，以及与多个调制单元103一一对应的多个第三光波导。调制单元103对应的出端口为调制单元103对应的第三光波导的一端。图18中以四个调制单元103以及四个第三光波导为例。
以一个调制单元103(多个调制单元103中的任一调制单元103)，该调制单元103对应的波长组、微环组和第三光波导为例：第一光波导和第三光波导均呈条状，且延伸方向相同；微环组包括：沿第一光波导和第三光波导的排布方向，依次间隔地排布在第一光波导和第三光波导之间的至少两个开关微环，不同开关微环的半径不同。第一光波导耦合微环组中与第一光波导相邻的开关微环，第二光波导耦合微环组中与第二光波导相邻的开关微环，微环组 中相邻的开关微环之间互相耦合。第一光波导用于接收光源发出的该波长组的光；控制单元与开关微环连接，在第一时间段，控制单元用于控制微环组将第一光波导中传输的该波长组中第一波长的光耦合至第三光波导后输出至该调制单元；在第二时间段，控制单元用于控制微环组将第一光波导中传输的该波长组中第二波长的光耦合至第三光波导后输出至该调制单元。
本申请实施例中，光发射机包括多个调制单元103，开关单元102包括该多个调制单元103一一对应的多个微环组，该多个微环组沿第一光波导的延伸方向依次间隔排布。另外，图18中以各个微环组相同为例，可以理解的是，各个微环组中开关微环的尺寸和数量也可以不同。该多个调制单元103一一对应的多个第三光波导可以分布在第一光波导的一侧或两侧，图18中以四个第三光波导分布在第一光波导的两侧，且第一光波导的每侧分布有两个第三光波导为例。
可以理解的是，第一光波导和第三光波导还可以有其他实现方式，比如，第一光波导和第三光波导的延伸方向可以不同(如垂直)。在第一光波导和第三光波导的延伸方向相互垂直时，微环组也可以只包括位于第一光波导和该微环组对应的第三光波导之间的一个开关微环，这个开关微环可以与第一光波导和该第三光波导均耦合。
开关单元102的第三种可实现方式与开关单元102的第二种可实现方式较为相似。区别在于：开关单元102的第二种可实现方式中，每个调制单元103对应的波长组中一个波长的光均从第二光波导输出，开关单元102具有一个输出端口；而开关单元102的第三种可实现方式中，每个调制单元103对应的波长组中一个波长的光从该调制单元103对应的微环组对应的第三光波导输出，开关单元102具有多个输出端口。
开关单元102的第三种可实现方式中除上述区别之外的部分可以参考开关单元102的第二种可实现方式，本申请实施例在此不做赘述。
(3)调制单元103。
调制单元103可以采用同相正交调制的方式调制光，也可以采用直接调制的方式调制光，本申请实施例对此不做限定。
在调制单元采用同相正交调制的方式调制光时，便可以调制得到同相正交光信号，使得该光发射机调制得到的光信号能够用于长距离传输，该光信号可以用于长距离波分光网络。示例地，同相正交调制可以是正交相移键控(quadrature phase shift keying，QPSK)调制、正交幅度调制(quadrature amplitude modulation，QAM)等。
直接调制只有强度调制，无相位调制。直接调制可以为“0”和“1”的开关键控调制，也可以为“00”、“01”、“10”和“11”的四电平脉冲幅度调制等。
(3.1)在调制单元103的第一种可实现方式中，调制单元103用于采用同相正交调制的方式调制光，如QPSK调制或QAM等。并且，该第一种可实现方式适用于光发射机包括一个或多个调制单元103，开关单元102具有一个出端口的情况。调制单元103的第一种可实现方式可以与开关单元102的第一种可实现方式或第二种可实现方式结合。示例地，图19中以光发射机包括一个调制单元103为例，图20以光发射机包括多个调制单元103为例。
请参考图19或图20，光发射机还包括：MZI波导105和移相器106。MZI波导105包括：并联且等长的第一波导臂和第二波导臂。第一波导臂的一端与第二波导臂的一端连接，第一波导臂的另一端与第二波导臂的另一端连接。调制单元103包括第一调制微环和第二调 制微环，第一调制微环和第二调制微环均可以称为MRM。第一调制微环的半径与第二调制微环的半径相同；图20中以各个调制单元相同为例，可以理解的是，各个调制单元中的第一调制微环的尺寸也可以不同，各个调制单元中的第二调制微环的尺寸也可以不同。第一调制微环与第一波导臂间隔且耦合，第二调制微环与第二波导臂间隔且耦合，并且，第一调制微环与第二调制微环不耦合。示例地，第一调制微环可以位于第一波导臂远离第二波导臂的一侧，第二调制微环可以位于第二波导臂远离第一波导臂的一侧。如图20所示，在光发射机包括多个调制单元103时，多个调制单元103沿第一波导臂的延伸方向依次间隔排布。请继续参考图19或图20，移相器106位于第二波导臂上，且位于光发射机中的所有调制单元103(上述至少一个调制单元103)远离MZI波导105的一端的一侧。
以一个调制单元103(至少一个调制单元103中的任一调制单元103)及其对应的波长组为例：MZI波导105的一端用于接收开关单元输出的光(如第一时间段的第一波长的光或第二时间段中的第二波长的光)；MZI波导105的一端在接收到该光后，可以将该光传输至上述第一波导臂和第二波导臂上。第一调制微环用于对第一波导臂中传输的光进行相移键控调制；第二调制微环用于对第二波导臂中传输的光进行相移键控调制；移相器106用于对经过的光(第二调制微环调制后的光)进行90度的移相，如移相器通过加载电压或电流对光进行90度的移相。
总的来说，光发射机包括至少一个调制单元103，MZI波导105的一端用于接收开关单元输出的该至少一个调制单元103中每个调制单元103对应的波长组中一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光；MZI波导105还可以将这些光传输至上述第一波导臂和第二波导臂上。每个调制单元中的第一调制微环用于对第一波导臂中传输的该调制单元对应的波长组中一个波长的光进行相移键控调制；每个调制单元中的第二调制微环用于对第二波导臂中传输的该调制单元对应的波长组中一个波长的光进行相移键控调制；移相器106用于对经过的光(第二调制微环调制后的光)进行90度的移相，如移相器通过加载电压或电流对光进行90度的移相。之后，从MZI波导的另一端输出的光包括：每个调制单元调制得到的光信号。
在本申请实施例中，MZI波导可以不仅包括第一波导臂和第二波导臂，并且还可以包括功率分束结构，该第一波导臂的一端和第二波导臂的一端通过Y形分支结构连接。图19和图20中以功率分束结构为Y形分支结构为例，该功率分束结构也可以是多模干涉结构等。Y形分支结构可以位于MZI波导的一端。MZI波导105的一端在接收到光后，可以利用功率分束结构将该光传输至上述第一波导臂和第二波导臂上。
对于调制单元的第一调制微环和第二调制微环中的任一调制微环，该调制微环可以包括环状光波导，以及位于环状光波导周围的电极，图19和图20中仅示出了调制微环中的环状光波导。该电极上可以加载驱动信号和偏置电压，使该调制微环能够对耦合的波导臂中传输的该调制单元对应的波长组中任一波长的光进行调制。
以对调制单元对应的波长组中任一波长的光进行上述同相正交调制为QPSK调制为例，第一调制微环用于对第一波导臂中传输的该波长的光进行二进制相移键控(binary phase shift keying，BPSK)调制；第二调制微环用于对第二波导臂中传输的该波长的光进行相同的BPSK调制；移相器106用于对经过的光(第二调制微环调制后的光)进行90度的移相。经过上述BPSK和90度的移相后，从MZI的另一端输出的光信号为QPSK光信号。第一调制微环对第 一波导臂中传输的该波长的光进行BPSK调制后得到的信号的星座图可以如图21所示；第二调制微环对第二波导臂中传输的该波长的光进行BPSK调制后得到的信号的星座图也可以如图21所示；移相器106对第二调制微环调制得到的信号进行90度移相后得到的信号的星座图可以如图22所示；从MZI的另一端输出的QPSK光信号的星座图可以如图23所示。在图21、图22和图23所示的星座图中，横轴I为同相轴，纵轴Q为正交轴，图中的黑点代表光信号，黑点偏离原点(横轴I和纵轴Q的交叉点)的距离代表光信号的强度，黑点与原点的连线与I轴正半轴的角度为光信号的相位。根据图21可知，该波长的光经过BPSK调制后得到的两种光信号的强度相同但相位相反(相位相差180度)。根据图22可知，移相器106对第二调制微环调制得到的信号进行90度移相后得到的两种光信号的强度相同但相位相反，且这两种光信号中的每种光信号与图21中的每种光信号具有90度的相位差。
调制单元的FSR与调制单元的几何参数有关，可以根据需要的FSR设置调制单元的几何参数。根据MRM的FSR的计算公式FSR＝λ 2/(2πR·n g)。假设调制单元对应的波长组中的波长均属于C波段，并且，第一调制微环和第二调制微环中的光波导均为某一掺杂工艺的硅光波导，那么可以将第一调制微环和第二调制微环的半径均设置为240微米，使该调制单元103的FSR为50GHz。
(3.2)在调制单元103的第二种可实现方式中，调制单元103也用于采用同相正交调制的方式调制光信号，如QPSK调制或QAM等。并且，该第二种可实现方式适用于光发射机包括一个调制单元103(调制单元103的个数为1)，开关单元102具有一个出端口的情况。调制单元103的第二种可实现方式可以与开关单元102的第一种可实现方式或第二种可实现方式结合。
示例地，如图24所示，调制单元103包括：第一非等臂MZM和第二非等臂MZM。光发射机还包括：MZI波导105和移相器106。其中，MZI波导包括：并联且等长的第一波导臂和第二波导臂；第一非等臂MZM位于第一波导臂上，第二非等臂MZM位于第二波导臂上；移相器位于第二波导臂上，且位于第二非等臂MZM远离MZI波导的一端的一侧；MZI波导的一端用于接收开关单元输出的光；第一非等臂MZM用于对第一波导臂中的光进行相移键控调制；第二非等臂MZM用于对第二波导臂中的光进行相移键控调制；移相器用于对经过的光进行90度的移相。
调制单元103的第二种可实现方式可以参考上述调制单元103的第一种可实现方式中适用于包括一个调制单元103的光发射机的情况(如图19所示)，区别在于，调制单元103的第二种可实现方式中是非等臂MZM是设置在波导臂上，而在调制单元103的第一种可实现方式中是调制微环与波导臂间隔。
对于第一非等臂MZM和第二非等臂MZM中的任一非等臂MZM，该非等臂MZM包括两个并联且不等长的波导臂，以及位于每个波导臂周围的电极，图24中仅示出了非等臂MZM中的两个并联且不等长的波导臂。这些电极上可以加载驱动信号和偏置电压，使该非等臂MZM能够对调制单元对应的波长组中任一波长的光进行调制。
调制单元的FSR与调制单元的几何参数有关，可以根据需要的FSR设置调制单元的几何参数。根据MZM的FSR的计算公式FSR＝λ 2/(ΔL·n g)，假设调制单元对应的波长组中的波长均属于C波段，并且，第一非等臂MZM和第二非等臂MZM中的光波导均为某一掺杂工艺的硅光波导，那么可以将第一非等臂MZM和第二非等臂MZM的长度差设置为1.5毫米， 使该调制单元103的FSR为50吉赫兹。
(3.3)在调制单元103的第三种可实现方式中，调制单元103用于采用直接调制的方式调制光信号，直接调制只有强度调制，无相位调制。并且，该第三种可实现方式适用于光发射机包括一个或多个调制单元103，开关单元102具有一个出端口的情况。调制单元103的第三种可实现方式可以与开关单元102的第一种可实现方式或第二种可实现方式结合。示例地，图25中以光发射机包括一个调制单元103为例，图26以光发射机包括多个调制单元103为例。
请参考图25或图26，在调制单元103的第三种可实现方式中，光发射机还包括：第四光波导107，调制单元103包括：调制微环(也称MRM)。图26中以各个调制单元相同为例，可以理解的是，不同调制单元中的调制微环的尺寸也可以不同。第四光波导107可以呈条状；调制微环与第四光波导107间隔且耦合；在光发射机包括多个调制单元103时，多个调制单元103中的多个调制微环沿第四光波导107的延伸方向依次排布。
以一个调制单元(光发射机中的任一调制单元)及其对应的波长组为例：第四光波导107用于接收开关单元102输出的该波长组中一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光；该调制微环用于对第四光波导107上的该光进行调制。
总的来说，光发射机包括至少一个调制单元，第四光波导107用于接收开关单元102输出的该至少一个调制单元中每个调制单元对应的波长组中一个波长的光；每个调制单元中的调制微环用于对第四光波导107上传输的该调制单元对应的波长组中任一波长的光进行调制。
示例地，调制单元中的调制微环包括环状光波导，以及位于环状光波导周围的电极，图25和图26中仅示出了调制微环中的环状光波导。该电极上可以加载驱动信号和偏置电压，使该调制微环能够对耦合的第四光波导中传输的该调制单元对应的波长组中任一波长的光进行调制。
调制单元的FSR与调制单元的几何参数有关，可以根据需要的FSR设置调制单元的几何参数。示例地，假设调制单元对应的波长组中的波长均属于C波段。对于图25所示的一个调制单元103，光源发出该调制单元103对应的波长组的光，该波长组中相邻波长的间隔为50吉赫兹，该调制单元103的FSR也可以是50吉赫兹；该调制单元103中调制微环中的光波导为某一掺杂工艺的硅光波导，可以根据MRM的FSR的计算公式FSR＝λ 2/(2πR·n g)，可以将调制微环的半径设置为60微米。对于图26所示的四个调制单元103，光源发出相邻波长的间隔为50吉赫兹的多个波长的光；该多个波长包括每个调制单元103对应的波长组，并且，每个调制单元103对应的波长组中相邻波长的间隔为200吉赫兹。示例地，四个调制单元103分别对应(200n+50)吉赫兹的波长、(200n+100)吉赫兹的波长、(200n+150)吉赫兹的波长和(200n+200)吉赫兹的波长，n≥0。每个调制单元103的FSR可以设置为200吉赫兹；调制单元103中调制微环中的光波导为某一掺杂工艺的硅光波导，可以根据MRM的FSR的计算公式FSR＝λ 2/(2πR·n g)，将这四个调制微环的半径设置为不同的半径。
(3.4)在调制单元103的第四种可实现方式中，调制单元103用于采用直接调制的方式调制光信号，并且，该第四种可实现方式适用于光发射机包括一个调制单元103(调制单元103的个数为1)，开关单元102具有一个出端口的情况。调制单元103的第四种可实现方式可以与开关单元102的第一种可实现方式或第二种可实现方式结合。如图27所示，在调制单 元103的第四种可实现方式中，调制单元103包括：非等臂MZM，非等臂MZM包括并联且长度不同的两个波导臂，这两个波导臂的两端分别连接。
示例地，调制单元中的非等臂MZM包括两个并联且不等长的波导臂，以及位于每个波导臂周围的电极，图27中仅示出了非等臂MZM中的两个并联且不等长的波导臂。这些电极上可以加载驱动信号和偏置电压，使该非等臂MZM能够对经过的该调制单元对应的波长组中任一波长的光进行调制。
(3.5)在调制单元103的第五种可实现方式中，调制单元103用于采用同相正交调制(或直接调制)的方式调制光信号，并且，该第五种可实现方式适用于光发射机包括多个调制单元103(调制单元103的个数大于1)，开关单元102具有一个出端口的情况。调制单元103的第五种可实现方式可以与开关单元102的第一种可实现方式或第二种可实现方式结合。
如图28所示，在调制单元103的第五种可实现方式中，光发射机还包括：第二DEMUX108和第二MUX 109；以一个调制单元103(光发射机中的任一调制单元)及其对应的波长组为例：第二DEMUX 108用于接收该波长组中一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光，并将该光传输至该调制单元103；该调制单元103用于将该光调制为光信号后，传输至第二MUX 109；第二MUX 109用于接收并输出该调制单元103调制得到的光信号。在这种可实现方式中，调制单元103可以是任一种能够对光进行调制的单元。
总的来说，光发射机包括多个调制单元103，第二DEMUX 108用于接收多个调制单元中每个调制单元103对应的波长组中一个波长的光，并将每个调制单元103对应的波长组中一个波长的光传输至该调制单元103；每个调制单元103用于将对应的波长组中该一个波长的光调制为光信号后，传输至第二MUX 109；第二MUX 109用于接收并输出每个调制单元103调制得到的光信号。
(3.6)在调制单元103的第六种可实现方式中，调制单元103用于采用同相正交调制(或直接调制)的方式调制光信号，并且，该第六种可实现方式适用于光发射机包括多个调制单元103，并且开关单元102具有多个出端口的情况(如前述开关单元102的第三种可实现方式)。调制单元103的第六种可实现方式可以与开关单元102的第三种可实现方式结合。
如图29所示，在调制单元103的第六种可实现方式中，光发射机还包括：第二MUX 109；以一个调制单元103(光发射机中的任一调制单元)及其对应的波长组为例：该调制单元用于接收开关单元中对应的出端口输出的该波长组中一个波长(如第一时间段的第一波长或第二时间段的第二波长)的光，并将该一个波长的光调制为光信号；第二MUX 109用于接收并输出该光信号。
进一步地，在上述调制单元103的第五种可实现方式和第六种可实现方式中，调制单元103可以是任意能够实现对光进行调制的结构，比如，调制单元103可以采用图24所示的结构。
根据前述介绍可知，本申请实施例提供的光源101的可实现方式、开关单元102的可实现方式以及调制单元103的可实现方式可以结合。
比如，假设光发射机需要发射一种波长的光信号，且该波长匹配DWDM标准，且该光信号采用同相正交调制的方式调制。那么，光源101可以采用(1.1)、(1.2)或(1.3)中的可实现方式；开关单元102可以采用(2.2)中的可实现方式；调制单元103可以采用(3.1) 或(3.2)中的可实现方式。
又比如，假设光发射机需要发射多种波长的光信号，且该波长匹配DWDM标准，且该光信号采用同相正交调制的方式调制。那么，光源101可以采用(1.1)、(1.2)或(1.3)中的可实现方式。开关单元102可以采用(2.1)或(2.2)中的可实现方式，且调制单元103可以采用(3.1)或(3.5)中的可实现方式；或者，开关单元102可以采用(2.3)中的可实现方式，且调制单元103可以采用(3.6)中的可实现方式。
再比如，假设光发射机需要发射多种波长的光信号，且该光信号采用直接调制的方式调制。那么，光源101可以采用(1.1)、(1.2)或(1.3)中的可实现方式；开关单元102可以采用(2.2)中的可实现方式；调制单元103可以采用(3.3)中的可实现方式。
可以理解的是，本申请实施例提供的光发射机还可以包括除以上介绍的单元之外的其他单元，本申请实施例对此不作限定。
示例地，该光发射机还可以包括功率放大单元，如片上掺铒氮化硅波导或掺铒光纤放大器等。功率放大单元位于光源和开关单元之间，功率放大单元用于对光源发出的光进行功率放大后传输至开关单元。
又示例地，在光源101是光源池时，光发射机还可以包括功率分束器，功率分束器用于对光源池发出的光分为多束光，并将其中一束光传输至开关单元。
综上所述，本申请实施例提供的光发射机中，光源能够向开关单元提供至少一个波长组的光，并且，控制单元能够控制开关单元向每个调制单元输出对应的波长组中第一波长或第二波长的光，以便于该调制单元对接收到的光进行调制。由于调制单元对应的波长组中第一波长和第二波长之差为该调制单元的FSR的整数倍，且开关单元输入该调制单元的光的波长能够在第一波长和第二波长之间切换，因此，在光发射机需要将光信号的波长在第一波长和第二波长之间切换时，该调制单元无需改变偏置电压，光源也无需改变提供的光，只需控制单元控制开关单元输出切换后的波长的光即可。可见，该光发射机切换光信号的波长的过程较为简单。
另外，本申请实施例提供的光发射机的结构简单。该光发射机无需泵浦光源和非线性器件，因此不存在泵浦光源引入高功耗的问题，以及不存在非线性器件引入噪声的问题，不影响光信号的质量和链路传输性能(如光信噪比(optical signal-to-noise ratio，OSNR))。并且，当光发射机需要输出多种波长的光信号时，该光发射机可以包括多个调制单元，但只需包括一个光源和一个开关单元即可，该光发射机的成本和功耗均较低。并且，本申请实施例提供的光发射机并不采用光电光转换的方式切换光信号的波长，本申请对光发射机中各个部分的性能要求较低，因此，较不容易引入噪声和出现光信号携带的信息丢失的问题。另外，本申请实施例提供的光发射机不对调制单元的调制方式进行限制，该调制单元可以采用同向正交调制方式或直接调制方式调制光。
基于本申请实施例提供的光发射机，本申请实施例还提供了一种光发射方法，该方法用于本申请提供的任一种光发射机，对于光发射机中的至少一个调制单元中的一个调制单元(任一个调制单元)，如图30所示，该光发射方法包括：
S101、光源向开关单元提供多个波长的光，其中，多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍；
S102、在第一时间段内，控制单元控制开关单元向调制单元输出第一波长的光，调制单元对输入的第一波长的光进行调制，以输出第一波长的调制光；
S103、在第二时间段内，控制单元控制开关单元向调制单元输出第二波长的光，调制单元对输入的第二波长的光进行调制，以输出第二波长的调制光。
其中，控制单元涉及的开关控制方法(如图31所示)可以包括：
S201、在第一时间段内，控制单元控制开关单元向调制单元输出光源提供的多个波长的光中第一波长的光，以便于调制单元对输入的第一波长的光进行调制，以输出第一波长的调制光；该多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍。
S202、在第二时间段内，控制单元控制开关单元向调制单元输出光源提供的多个波长的光中第二波长的光，以便于调制单元对输入的第二波长的光进行调制，以输出第二波长的调制光。
可选地，第一波长与第二波长之差为FSR。
可选地，光发射机包括：多个调制单元；光源发出的光的多个波长包括：多个调制单元一一对应的多个波长组；对于一个调制单元对应的波长组，该波长组包括第一波长和第二波长，且第一波长和第二波长之差为该调制单元的FSR的整数倍；不同波长组中的第一波长不同，不同波长组中的第二波长不同。在S102中，控制单元可以控制开关单元向该调制单元输出对应的波长组中第一波长的光；在S103中，控制单元可以控制开关单元向调制单元输出对应的波长组中第二波长的光。
本申请实施例提供的光发射方法与开关单元的可实现方式相关。
当开关单元采用上述(2.1)中所述的可实现方式时，以一个调制单元为例，在S101中，光源向第一DEMUX提供该调制单元对应的波长组的光。在S102中，控制单元控制光开关组将该波长组中第一波长的光传输至第一MUX后传输至该调制单元；在S103中，控制单元控制光开关组将该波长组中第二波长的光传输至第一MUX后传输至该调制单元。
当开关单元采用上述(2.2)中所述的可实现方式时，以一个调制单元为例，在S101中，光源向第一光波导提供该调制单元对应的波长组的光。在S102中，控制单元控制微环组将第一光波导中传输的第一波长的光耦合至第二光波导后输出至调制单元；在S103中，控制单元控制微环组将第一光波导中传输的第二波长的光耦合至第二光波导后输出至调制单元。
当开关单元采用上述(2.3)中所述的可实现方式时，在S101中，光源向第一光波导提供多个波长的光。对于一个调制单元对应的波长组、微环组和第三光波导，在S102中，控制单元可以控制微环组将第一光波导中传输的波长组中第一波长的光耦合至第三光波导后输出，在S103中控制单元可以控制微环组将第一光波导中传输的波长组中第二波长的光耦合至第三光波导后输出。
可以理解的是，控制单元为了实现上述各方法所描述的功能，需包含执行各个功能相应的硬件和/或软件模块。结合本文中所公开的实施例描述的各方法的执行过程，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。本领域技术人员可以结合实施例对每个特定的应用来使用不同方式来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本实施例可以根据上述方法实施例对相应的控制单元进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块可以采用硬件的形式实现。需要说明的是，本实施例中对模块的划分是示意性的，具体作为一种逻辑功能可能的划分方式，实际实现时可以有另外的划分方式。
当采用功能模块划分方式时，下面将结合图32描述本申请所提供的属于控制单元的开关控制装置。对于光发射机中的至少一个调制单元中的一个调制单元，如图32所示，开关控制装置包括：第一控制模块301和第二控制模块302。其中，第一控制模块301，用于在第一时间段内，控制开关单元向调制单元输出光源提供的多个波长的光中第一波长的光，以便于调制单元对输入的第一波长的光进行调制，以输出第一波长的调制光；该多个波长包括第一波长和第二波长，第一波长和第二波长之差为调制单元的FSR的整数倍；第二控制模块302，用于在第二时间段内，控制开关单元向调制单元输出光源提供的多个波长的光中第二波长的光，以便于调制单元对输入的第二波长的光进行调制，以输出第二波长的调制光。
当采用硬件实现时，本申请所提供的属于控制单元的开关控制装置包括：处理器和存储器，存储器中存储有程序，处理器用于执行存储器中存储的程序，以实现本申请实例提供的任一种由控制单元执行的开关控制方法。
本申请实施例还提供了一种芯片，所述芯片包括可编程逻辑电路和/或程序指令，当所述芯片运行时用于实现本申请实例提供的任一种由控制单元执行的开关控制方法。
本申请实施例还提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当所述指令在计算机上运行时，使得计算机执行本申请实例提供的任一种由控制单元执行的开关控制方法。
本申请实施例还提供了一种包含指令的计算机程序产品，当所述计算机程序产品在计算机上运行时，使得计算机执行本申请实例提供的任一种由控制单元执行的开关控制方法。
上述任一种由控制单元执行的开关控制方法实施例可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现，所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机的可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线)或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者包含一个或多个可用介质集成的服务器、数据中心等数据存储装置。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质，或者半导体介质(例如固态硬盘)等。
在本申请中，术语“第一”和“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性。术语“至少一个”指一个或多个，“多个”指两个或两个以上，除非另有明确的限定。
本申请实施例提供的各种不同类型的实施例均可以相互参考，本申请实施例对此不做限定。在本申请提供的相应实施例中，应该理解到，所揭露的光发射机、光模块、光通信设备、 光通信系统、光发射方法、开关控制方法及装置等可以通过其他的构成方式实现。例如，以上所描述的实施例仅仅是示意性的，例如，单元或模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或模块可以结合或者可以集成，或一些特征可以忽略，或不执行。
作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元描述的部件可以是或者也可以不是物理单元。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (16)

  1. 一种光发射机，其特征在于，包括：光源、开关单元、调制单元和控制单元；
    所述光源用于向所述开关单元提供多个波长的光，其中，所述多个波长包括第一波长和第二波长，所述第一波长和所述第二波长之差为所述调制单元的自由光谱范围FSR的整数倍；
    所述控制单元用于在第一时间段内控制所述开关单元向所述调制单元输出所述第一波长的光，以及在第二时间段内控制所述开关单元向所述调制单元输出所述第二波长的光；
    所述调制单元用于在所述第一时间段内对输入的所述第一波长的光进行调制，以输出所述第一波长的调制光，以及在所述第二时间段内对输入的所述第二波长的光进行调制，以输出所述第二波长的调制光。
  2. 根据权利要求1所述的光发射机，其特征在于，所述第一波长与所述第二波长之差为所述FSR。
  3. 根据权利要求1或2所述的光发射机，其特征在于，所述光发射机包括：多个调制单元；所述多个波长包括：所述多个调制单元一一对应的多个波长组；
    对于一个所述调制单元对应的所述波长组，所述波长组包括所述第一波长和所述第二波长，且所述第一波长和所述第二波长之差为所述调制单元的FSR的整数倍；不同所述波长组中的所述第一波长不同，不同所述波长组中的所述第二波长不同；
    所述控制单元用于：在所述第一时间段内控制所述开关单元向所述调制单元输出对应的所述波长组中所述第一波长的光，以及在第二时间段内控制所述开关单元向所述调制单元输出对应的所述波长组中所述第二波长的光。
  4. 根据权利要求1至3任一所述的光发射机，其特征在于，所述开关单元具有一个出端口，所述开关单元用于从所述出端口输出所述第一波长和所述第二波长的光。
  5. 根据权利要求4所述的光发射机，其特征在于，所述开关单元包括：第一光波导、第二光波导和微环组，所述开关单元的出端口为所述第二光波导的一端；
    所述第一光波导用于接收所述光源发出的所述多个波长的光；
    所述控制单元用于：在所述第一时间段内控制所述微环组将所述第一光波导中传输的所述第一波长的光耦合至所述第二光波导后输出；以及，在所述第二时间段内控制所述微环组将所述第一光波导中传输的所述第二波长的光耦合至所述第二光波导后输出。
  6. 根据权利要求3所述的光发射机，其特征在于，所述开关单元具有与所述多个调制单元一一对应的多个出端口，所述开关单元用于从所述调制单元对应的所述出端口输出所述调制单元对应的所述波长组中所述第一波长和所述第二波长的光。
  7. 根据权利要求6所述的光发射机，其特征在于，所述开关单元包括：第一光波导，与所述多个调制单元一一对应的多个微环组，以及与所述多个调制单元一一对应的多个第三光 波导；所述调制单元对应的所述出端口为所述调制单元对应的所述第三光波导的一端；
    所述第一光波导用于接收所述光源发出的所述多个波长的光；
    对于一个调制单元对应的所述波长组、所述微环组和所述第三光波导，所述控制单元用于：在所述第一时间段内控制所述微环组将所述第一光波导中传输的所述波长组中所述第一波长的光耦合至所述第三光波导后输出，以及在所述第二时间段内控制所述微环组将所述第一光波导中传输的所述波长组中所述第二波长的光耦合至所述第三光波导后输出。
  8. 根据权利要求4或5所述的光发射机，其特征在于，所述调制单元包括：半径相同的第一调制微环和第二调制微环，所述光发射机还包括：马赫增德干涉仪MZI波导和移相器；
    所述MZI波导包括：等长的第一波导臂和第二波导臂；所述第一调制微环与所述第一波导臂间隔且耦合，所述第二调制微环与所述第二波导臂间隔且耦合；所述移相器位于所述第二波导臂上，且位于所述调制单元远离所述MZI波导的一端的一侧；
    所述MZI波导的一端用于接收所述开关单元输出的光；所述第一调制微环用于对所述第一波导臂中传输的光进行相移键控调制；所述第二调制微环用于对所述第二波导臂中传输的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。
  9. 根据权利要求1或2所述的光发射机，其特征在于，所述调制单元包括：第一非等臂马赫增德调制器MZM和第二非等臂MZM，所述光发射机还包括：MZI波导和移相器；
    所述MZI波导包括：等长的第一波导臂和第二波导臂；所述第一非等臂MZM位于所述第一波导臂上，所述第二非等臂MZM位于所述第二波导臂上；所述移相器位于所述第二波导臂上，且位于所述第二非等臂MZM远离所述MZI波导的一端的一侧；
    所述MZI波导的一端用于接收所述开关单元输出的光；所述第一非等臂MZM用于对所述第一波导臂中传输的光进行相移键控调制；所述第二非等臂MZM用于对所述第二波导臂中传输的光进行所述相移键控调制；所述移相器用于对经过的光进行90度的移相。
  10. 根据权利要求4或5所述的光发射机，其特征在于，所述调制单元包括：与所述第四光波导间隔且耦合的调制微环，所述光发射机还包括：第四光波导；
    所述第四光波导用于接收所述开关单元输出的光，所述调制微环用于对所述第四光波导上的传输的光进行调制。
  11. 一种光发射方法，其特征在于，所述方法由权利要求1至10任一所述的光发射机执行，所述光发射机包括：光源、开关单元、调制单元和控制单元；所述方法包括：
    所述光源向所述开关单元提供多个波长的光，其中，所述多个波长包括第一波长和第二波长，所述第一波长和所述第二波长之差为所述调制单元的自由光谱范围FSR的整数倍；
    在第一时间段内，所述控制单元控制所述开关单元向所述调制单元输出所述第一波长的光，所述调制单元对输入的所述第一波长的光进行调制，以输出所述第一波长的调制光；
    在第二时间段内，所述控制单元控制所述开关单元向所述调制单元输出所述第二波长的光，所述调制单元对输入的所述第二波长的光进行调制，以输出所述第二波长的调制光。
  12. 根据权利要求11所述的方法，其特征在于，所述开关单元包括：第一光波导、第二光波导和微环组；
    所述光源向所述开关单元提供多个波长的光，包括：所述光源向所述第一光波导提供所述多个波长的光；
    所述控制单元控制所述开关单元向所述调制单元输出所述第一波长的光，包括：所述控制单元控制所述微环组将所述第一光波导中传输的所述第一波长的光耦合至所述第二光波导后输出至所述调制单元；
    所述控制单元控制所述开关单元向所述调制单元输出所述第二波长的光，包括：所述控制单元控制所述微环组将所述第一光波导中传输的所述第二波长的光耦合至所述第二光波导后输出至所述调制单元。
  13. 根据权利要求11所述的方法，其特征在于，所述光发射机包括：多个调制单元；所述多个波长包括：所述多个调制单元一一对应的多个波长组；对于一个所述调制单元对应的所述波长组，所述波长组包括所述第一波长和所述第二波长，且所述第一波长和所述第二波长之差为所述调制单元的FSR的整数倍；不同所述波长组中的所述第一波长不同，不同所述波长组中的所述第二波长不同；所述开关单元包括：第一光波导，与所述多个调制单元一一对应的多个微环组，以及与所述多个调制单元一一对应的多个第三光波导；
    所述光源向所述开关单元提供多个波长的光，包括：所述光源向所述第一光波导提供所述多个波长的光；
    所述控制单元控制所述开关单元向所述调制单元输出所述第一波长的光，包括：对于一个调制单元对应的所述波长组、所述微环组和所述第三光波导，所述控制单元控制所述微环组将所述第一光波导中传输的所述波长组中所述第一波长的光耦合至所述第三光波导后输出至所述调制单元；
    所述控制单元控制所述开关单元向所述调制单元输出所述第二波长的光，包括：对于一个调制单元对应的所述波长组、所述微环组和所述第三光波导，所述控制单元控制所述微环组将所述第一光波导中传输的所述波长组中所述第二波长的光耦合至所述第三光波导后输出至所述调制单元。
  14. 一种光模块，其特征在于，包括：权利要求1至10任一所述的光发射机，以及光接收机。
  15. 一种光通信设备，其特征在于，包括：权利要求14所述的光模块，以及处理电路；所述处理电路用于向所述光模块提供携带待传输数据的驱动信号，所述光模块中的调制单元用于基于所述驱动信号对光进行调制。
  16. 一种光通信系统，其特征在于，包括：多个权利要求15所述的光通信设备。
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