WO2024113118A1 - 光调制器、发射装置、通信系统及调制方法 - Google Patents

光调制器、发射装置、通信系统及调制方法 Download PDF

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WO2024113118A1
WO2024113118A1 PCT/CN2022/134808 CN2022134808W WO2024113118A1 WO 2024113118 A1 WO2024113118 A1 WO 2024113118A1 CN 2022134808 W CN2022134808 W CN 2022134808W WO 2024113118 A1 WO2024113118 A1 WO 2024113118A1
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optical signal
optical
modulated
electro
transmission direction
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PCT/CN2022/134808
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English (en)
French (fr)
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秦扬
彭星
郑泽秋
杨哲
金宇骋
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华为技术有限公司
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • 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
    • H04B10/516—Details of coding or modulation
    • H04B10/548—Phase or frequency modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems

Definitions

  • the present application relates to the field of communication technology, and in particular to an optical modulator, a transmitting device, a communication system and a modulation method.
  • Optical modulators are important active devices in the field of optical communications and are widely used in optical transceiver module products. They work by converting high and low voltage modulation signals into strong and weak light intensity modulation signals.
  • the optical modulator is a Mach-Zehnder modulator (MZM).
  • the size of the optical modulator is generally large, such as the silicon-based MZM is generally 1 to 3 millimeters (mm) long, and the length of the lithium niobate MZM is generally around 1 centimeter (cm), it will lead to insufficient integration and is not conducive to miniaturization development.
  • the present application provides an optical modulator, a transmitting device, a communication system and a modulation method, which are used to reduce the size of the optical modulator and improve the integration.
  • the present application provides an optical modulator, which may include: a beam combiner/splitter, a first electro-optical phase shifter and a second electro-optical phase shifter connected to the beam combiner/splitter, a first inverter connected to the first electro-optical phase shifter, and a second inverter connected to the second electro-optical phase shifter.
  • the beam combiner/splitter is used to divide the input optical signal into a first optical signal and a second optical signal, and input the first optical signal into the first electro-optical phase shifter, and input the second optical signal into the second electro-optical phase shifter;
  • the first electro-optical phase shifter is used to perform a first phase modulation on the first optical signal to obtain a first modulated optical signal, and input the first modulated optical signal into the first inverter;
  • the first inverter is used to adjust the transmission direction of the first modulated optical signal from the first transmission direction to a second transmission direction, and the second transmission direction is opposite to the first transmission direction, so that the first modulated optical signal is input into the first electro-optical phase shifter;
  • the first electro-optical phase shifter is also used to perform the first phase modulation on the first modulated optical signal to obtain a second modulated optical signal, and input the second modulated optical signal into the combiner/splitter;
  • the second electro-optical phase shifter is used to perform the second phase modulation on the second optical signal to obtain a third modulated optical signal, and input the third modulated optical signal into the second inverter;
  • the second inverter is used to adjust the transmission direction of the third modulated optical signal from the third transmission direction to a fourth transmission direction, and the fourth transmission direction is opposite to the third transmission direction, so that the third modulated optical signal is input into the second electro-optical phase shifter;
  • the second electro-optical phase shifter is also used to perform the second phase modulation on the third modulated optical signal to obtain a fourth modulated optical signal, and input the fourth modulated optical signal into the combiner/splitter;
  • the beam combiner/splitter is further used to combine the second modulated optical signal and the fourth modulated optical signal to form a modulated optical signal, and output the modulated optical signal.
  • the first inverter since the first inverter is provided in the optical modulator, the first optical signal can be transmitted in the reverse direction after undergoing one phase modulation, so that the first optical signal undergoes two phase modulations in the phase modulation area of the first electro-optical phase shifter (i.e., the phase shift of the first optical signal is doubled).
  • the second inverter since the second inverter is provided in the optical modulator, the second optical signal can be transmitted in the reverse direction after undergoing one phase modulation, so that the second optical signal undergoes two phase modulations in the phase modulation area of the second electro-optical phase shifter (i.e., the phase shift of the second optical signal is doubled).
  • the optical signal undergoes only one phase modulation in the phase modulation area of the modulation arm. Therefore, compared with the conventional optical modulator, the length of the phase modulation area in the first electro-optical phase shifter and the second electro-optical phase shifter in the optical modulator can be halved, thereby effectively reducing the size of the optical modulator and improving the integration.
  • the first reflector is a first reflector, a first waveguide loopback or a first grating structure
  • the second reflector is a second reflector, a second waveguide loopback or a second grating structure.
  • the splitting ratio of the first optical signal and the second optical signal is 1:m, m>0 and m ⁇ 1. That is to say, the combiner/splitter can split the input optical signal in non-equal proportions. In this way, after the first optical signal and the second optical signal are phase modulated respectively, since the first optical signal and the second optical signal are non-equal proportions, after the first optical signal and the second optical signal are combined, the phase offset of the first optical signal and the phase offset of the second optical signal will not be completely offset. Therefore, compared with the input optical signal, the final output optical signal will be superimposed with additional phase modulation, so that pre-compensation can be achieved.
  • the beam combiner/splitter is a multi-mode interferometer.
  • the optical modulator further includes a microring resonator array connected to the beam combiner/splitter; the microring resonator array is used to perform delay compensation processing on the modulated optical signal output by the beam combiner/splitter.
  • an embodiment of the present application provides a transmitting device, which includes an optical modulator described in any possible design of the first aspect.
  • the splitting ratios of the N optical signals are the same.
  • the N optical modulators include the optical modulators described in any possible design of the first aspect above.
  • an embodiment of the present application provides a communication system, which includes a receiving device, an optical fiber link, and the transmitting device described in the second aspect or the third aspect, and the optical fiber link connects the transmitting device and the receiving device.
  • an embodiment of the present application provides a modulation method, which can be applied to the optical modulator of the first aspect.
  • the method includes: dividing an input optical signal into a first optical signal and a second optical signal; performing a first phase modulation on the first optical signal in a first phase modulation zone to obtain a first modulated optical signal; and adjusting the transmission direction of the first modulated optical signal from the first transmission direction to a second transmission direction, the second transmission direction being opposite to the first transmission direction, so that the first modulated optical signal is transmitted to the first phase modulation zone; performing the first phase modulation on the first modulated optical signal in the first phase modulation zone to obtain a second modulated optical signal; performing a second phase modulation on the second optical signal in the second phase modulation zone to obtain a third modulated optical signal; and adjusting the transmission direction of the third modulated optical signal from the third transmission direction to a fourth transmission direction, the fourth transmission direction being opposite to the third transmission direction, so that the third modulated optical signal is transmitted to the second phase modulation zone;
  • FIG1 is a schematic diagram of wavelength division multiplexing provided in an embodiment of the present application.
  • FIG2 is a schematic diagram of a conventional optical modulator (such as MZM) provided in an embodiment of the present application;
  • FIG3 is a schematic diagram of the structure of an optical modulator provided in Example 1 of the present application.
  • FIG4 is a schematic diagram of the structure of an optical modulator provided in Embodiment 2 of the present application.
  • FIG5 is a schematic diagram of a structure of a transmitting device provided in Embodiment 3 of the present application.
  • FIG6 is a schematic diagram of another structure of a transmitting device provided in Embodiment 3 of the present application.
  • FIG7 is a schematic diagram of a communication system provided in an embodiment of the present application.
  • FIG8 is a schematic diagram of a flow chart corresponding to the modulation method provided in an embodiment of the present application.
  • the C-RAN network architecture can realize the centralized management of the baseband processing unit (BBU).
  • BBU baseband processing unit
  • the radio frequency unit is, for example, a remote radio unit (RRU).
  • wavelength division multiplexing (WDM) technology can be used to achieve optical fiber multiplexing.
  • WDM wavelength division multiplexing
  • multiple RF units can be connected to BBU through a wavelength division device to multiplex one optical fiber, thereby improving the utilization of optical fiber.
  • the main optical fiber (the optical fiber between the wavelength division device on the RF unit side and the wavelength division device on the BBU side) connected to the RF units that perform optical fiber multiplexing through the same wavelength division device is the same, and only the length of the pigtail between the wavelength division device on the RF unit side and each RF unit may be different.
  • WDM technology can also be called lightwave multiplexing technology. It is a data transmission technology that combines two or more optical signals of different wavelengths through a multiplexer at the transmitting end, couples them into the same optical fiber for transmission, and separates the optical signals of various wavelengths through a demultiplexer at the receiving end.
  • the basic principle is to carry different optical signals by different colors (wavelength frequencies), and then multiplex them on one optical fiber for transmission.
  • Commonly used wavelength division multiplexing includes coarse wavelength division multiplexing (CWDM), dense wavelength division multiplexing (DWDM), and lan-wavelength division multiplexing (LWDM).
  • a wavelength division device is a device that uses WDM technology to support the transmission of two or more optical signals of different wavelengths in one optical fiber.
  • a wavelength division device can be a CWDM wavelength division device, a DWDM wavelength division device, or a LWDM wavelength division device.
  • a wavelength division device can standardize the wavelength of the optical modules of the RF unit and BBU. Different wavelength division devices have different specifications for the wavelength of the optical modules of the RF unit and BBU ports.
  • the wavelength division device is a 6-wavelength CWDM wavelength division device
  • the wavelength of the optical module of the RF unit can be 1271, 1291, or 1311 (unit: nanometers (nm)
  • the wavelength of the optical module of the BBU can be 1331, 1351, or 1371 (unit: nanometers).
  • the optical module of BBU may include three optical modulators, which modulate optical signals of three wavelengths (i.e., 1331 or 1351 or 1371nm) respectively, and input the modulated optical signals into the wavelength division device, which then transmits the optical signals of the three wavelengths to different RF units through one optical fiber.
  • three optical modulators which modulate optical signals of three wavelengths (i.e., 1331 or 1351 or 1371nm) respectively, and input the modulated optical signals into the wavelength division device, which then transmits the optical signals of the three wavelengths to different RF units through one optical fiber.
  • FIG2 is a schematic diagram of a conventional optical modulator (such as an MZM).
  • the conventional optical modulator 10 may include: a beam splitter 11, and a modulation arm arranged on each branch of the beam splitter 11.
  • the number of branches of the beam splitter 11 is two, and the two branches are symmetrically arranged, that is, the two modulation arms (modulation arm 12 and modulation arm 13) are symmetrically arranged.
  • the conventional optical modulator 10 also includes: a beam combiner 14 connected to the two modulation arms.
  • the beam splitter 11 splits the optical signal into two beams of equal power or two optical signals (i.e., the splitting ratio of the two optical signals is 1:1), for example, the two optical signals are optical signal a and optical signal b, and the optical signal a is input to the modulation arm 12, and the optical signal b is input to the modulation arm 13.
  • the modulation arm 12 performs phase modulation on the optical signal a to obtain the modulated optical signal a, and inputs the modulated optical signal a to the beam combiner 14;
  • the modulation arm 13 performs phase modulation on the optical signal b to obtain the modulated optical signal b, and inputs the modulated optical signal b to the beam combiner 14.
  • the beam combiner 14 combines the modulated optical signal a and the adjusted optical signal b, and outputs the combined optical signal.
  • the traditional optical modulator uses the principle of optical interference to convert phase modulation into intensity modulation. Specifically, when the phases of the two beams of light output by the two modulation arms are the same, according to the interference theory of light, the interference is constructive when the beams are combined, and the output light intensity is the maximum, which can be regarded as a high-level signal; when there is a phase difference between the two beams of light output by the two modulation arms, the light intensity is not the maximum after the beams are combined and interference occurs. If the phase difference is ⁇ , the interference is destructive, and the output light intensity is the minimum, which can be regarded as a low-level signal. In this way, the light intensity is destructive or constructive according to the phase difference of the two beams of light, thereby forming a change in strength and realizing the modulation of the optical signal.
  • lithium niobate MZM is formed by locally doping single crystal lithium niobate material through titanium diffusion or proton exchange process.
  • the refractive index difference between the core and cladding of the waveguide is very small, and the waveguide has poor binding ability for the light field.
  • the length of the phase modulation zone needs to be designed to be very long, which makes the size of the packaged optical modulator larger, resulting in insufficient integration and is not conducive to miniaturization development.
  • the embodiment of the present application improves the structure of the traditional optical modulator by introducing an inverter into the optical modulator so that the optical signal can undergo two phase modulations back and forth in the phase modulation zone, thereby reducing the length of the phase modulation zone, thereby reducing the size of the optical modulator and improving the integration.
  • the optical modulator provided in the embodiment of the present application can be made on a chip, or can also be directly assembled in an optical module.
  • the optical modulator provided in the embodiment of the present application can be applied to communication equipment in communication scenarios such as wireless fronthaul, midhaul, data center, access network or backbone network; for example, the optical modulator provided in the embodiment of the present application can be applied to the above-mentioned BBU (for example, assembled in the optical module of the BBU).
  • FIG3 is a schematic diagram of the structure of the optical modulator provided in Embodiment 1 of the present application.
  • the optical modulator 20 may include: a beam combiner/splitter 21, a first electro-optical phase shifter 22 and a second electro-optical phase shifter 23 connected to the beam combiner/splitter 21 (i.e., the first electro-optical phase shifter 22 and the second electro-optical phase shifter 23 are located on two branches of the beam combiner/splitter 21), a first inverter 24 connected to the first electro-optical phase shifter 22, and a second inverter 25 connected to the second electro-optical phase shifter 23.
  • the beam combiner/splitter 21 is used to: split the input optical signal into a first optical signal and a second optical signal, and input the first optical signal into the first electro-optical phase shifter 22, and input the second optical signal into the second electro-optical phase shifter 23.
  • the input end of the beam combiner/splitter 21 can be connected to a laser, and the laser is used to input the optical signal to the beam combiner/splitter 21.
  • the laser can be a continuous wave (CW) laser.
  • the first electro-optical phase shifter 22 is used for performing a first phase modulation on the first optical signal to obtain a first modulated optical signal, and inputting the first modulated optical signal into the first inverter 24 .
  • the first inverter 24 is used to adjust the transmission direction of the first modulated optical signal from the first transmission direction to the second transmission direction, where the second transmission direction is opposite to the first transmission direction, so that the first modulated optical signal is input into the first electro-optical phase shifter 22 .
  • the first electro-optical phase shifter 22 is further used to perform a first phase modulation on the first modulated optical signal to obtain a second modulated optical signal, and input the second modulated optical signal into the beam combiner/splitter 21 .
  • the second electro-optical phase shifter 23 is used for performing a second phase modulation on the second optical signal to obtain a third modulated optical signal, and inputting the third modulated optical signal into the second inverter 25 .
  • the second inverter 25 is used to adjust the transmission direction of the third modulated optical signal from the third transmission direction to a fourth transmission direction, which is opposite to the third transmission direction, so that the third modulated optical signal is input into the second electro-optical phase shifter 23 .
  • the second electro-optical phase shifter 23 is further used to perform a second phase modulation on the third modulated optical signal to obtain a fourth modulated optical signal, and input the fourth modulated optical signal into the beam combiner/splitter 21 .
  • the beam combiner/splitter 21 is further used to combine the second modulated optical signal and the fourth modulated optical signal to form a modulated optical signal, and output the modulated optical signal.
  • the first inverter 24 is provided in the optical modulator 20
  • the first optical signal can be transmitted in reverse after undergoing one phase modulation, so that the first optical signal undergoes two phase modulations in the phase modulation area of the first electro-optical phase shifter 22 (i.e., the phase shift of the first optical signal is doubled).
  • the second inverter 25 is provided in the optical modulator 20
  • the second optical signal can be transmitted in reverse after undergoing one phase modulation, so that the second optical signal undergoes two phase modulations in the phase modulation area of the second electro-optical phase shifter 23 (i.e., the phase shift of the second optical signal is doubled).
  • the optical signal undergoes only one phase modulation in the phase modulation area of the modulation arm. Therefore, compared with the conventional optical modulator 10, the length of the phase modulation area in the first electro-optical phase shifter 22 and the second electro-optical phase shifter 23 in the optical modulator 20 can be halved, thereby effectively reducing the size of the optical modulator and improving the integration.
  • the electrical signal loss can be effectively reduced (the longer the length of the phase modulation zone, the greater the electrical signal loss), thereby facilitating the reduction of the amplitude requirements for the driving electrical signals in the first electro-optical phase shifter 22 and the second electro-optical phase shifter 23.
  • the optical ports (i.e., the input port of the optical signal and the output port of the modulated optical signal) in the optical modulator 20 are both located at the beam combiner/splitter 21, i.e., the input port of the optical signal and the output port of the modulated optical signal are on the same side; whereas in the conventional optical modulator 10, the input port of the optical signal is located at the beam splitter 11, and the output port of the modulated optical signal is located at the beam combiner 14, i.e., the input port of the optical signal and the output port of the modulated optical signal are located on both sides of the modulation arm. Therefore, compared with the conventional optical modulator 10, the optical modulator 20 sets the optical ports on the same side, which can reduce the routing loss, the difficulty of optical port coupling, and the number of fiber arrays (FA).
  • FA fiber arrays
  • optical modulator 20 The various components included in the optical modulator 20 are described below.
  • the beam combiner/splitter 21 may be a multi-mode interferometer (MMI), for example, the beam combiner/splitter 21 is a 2*2MMI.
  • MMI multi-mode interferometer
  • One side of the 2*2MMI has two ports, namely port 1 and port 2, and the other side thereof also has two ports, namely port 3 and port 4.
  • Port 1 is used to input an optical signal
  • port 2 is used to output a modulated optical signal
  • port 3 is used to output a first optical signal
  • port 4 is used to output a second optical signal.
  • the DC phase difference between the second modulated optical signal and the fourth modulated optical signal can be controlled by adjusting the working point of the optical modulator 20 and/or the length difference between the phase modulation area of the first electro-optical phase shifter 22 and the phase modulation area of the second electro-optical phase shifter 23, so that the modulated optical signal after the second modulated optical signal and the fourth modulated optical signal are combined can be output from another port of the 2*2MMI without backflow to the input port.
  • the beam combiner/splitter 21 may also be other possible interferometers, such as a Mach-Zehnder interferometer (MZI), without specific limitation.
  • MZI Mach-Zehnder interferometer
  • the combiner/splitter 21 can split the input optical signal into a first optical signal and a second optical signal according to a splitting ratio of 1:m, where m>0 and m ⁇ 1.
  • the combiner/splitter 21 can perform non-equal-proportional splitting on the input optical signal.
  • the phase offset of the first optical signal and the phase offset of the second optical signal will not be completely offset. Therefore, compared with the input optical signal, the final output optical signal will be superimposed with additional phase modulation, so that pre-compensation can be achieved.
  • the pre-compensation described in the embodiments of the present application can occur before the optical fiber link, that is, the optical signal has been modulated before the dispersion occurs, for example, the optical modulator 20 is set on the transmitting device side, that is, the phase modulation of the optical signal is performed on the transmitting device side. Therefore, after the optical signal output by the optical modulator 20 enters the optical fiber link, even if the optical signal is dispersed in the optical fiber link, the optical signal has been pre-compensated when entering the optical fiber link, which can effectively reduce the problem caused by the dispersion.
  • the dispersion compensation of the optical signal by the optical modulator 20 of the present application is described in detail below using mathematical derivation.
  • the electric field of the first optical signal is:
  • x(t) represents a composite signal.
  • x(t) represents a composite signal after the real signal s(t) and the DC bias b (different DC biases correspond to different operating points), that is:
  • A is the component corresponding to the first optical signal output by the combiner/splitter 21
  • B is the component corresponding to the second optical signal output by the combiner/splitter 21.
  • a and B also satisfy:
  • the working point is selected in the linear region (in the linear region, since the mapping function relationship between the electrical signal and the optical signal is a simple linear relationship, the information carried by the electrical signal will not change or be distorted after being modulated into the optical signal. Since the relationship between the DC bias voltage and the output optical power of the optical modulator is similar to a sin curve, if the working point is selected in the middle of the sin curve (such as the position of sin0, sin ⁇ ), it is considered that the optical modulator is working in the linear region), the above formula (5) can be approximated as:
  • the transmission of an optical signal in a 10 km long optical fiber link is taken as an example.
  • the transfer function generated by the dispersion effect is h
  • the electric field of the optical signal received by the receiving device is:
  • the intensity of the optical signal received by the receiving device is:
  • the splitting ratio of the beam combiner/splitter 21 is not equal to 1, m ⁇ 1, that is, A ⁇ B.
  • the 4(A 2 -B 2 )b*S( ⁇ )*sin( ⁇ 2 ⁇ L/2) part in I( ⁇ ) is not zero, dispersion compensation can be achieved, and according to the relative size of A and B, the positive compensation direction or negative compensation direction of the optical signal can be controlled.
  • the first electro-optical phase shifter 22 may include a first traveling wave electrode, and the first electro-optical phase shifter 22 may load a high-speed electrical signal into a phase modulation region (referred to as a first phase modulation region) of the first electro-optical phase shifter 22 through the first traveling wave electrode, and change the refractive index of the first phase modulation region by changing the carrier concentration in the waveguide of the first phase modulation region, thereby performing a first phase modulation on the optical signal passing through the first phase modulation region.
  • a phase modulation region referred to as a first phase modulation region
  • the second electro-optical phase shifter 23 may include a second traveling wave electrode.
  • the second electro-optical phase shifter 23 may load a high-speed electrical signal into a phase modulation region (referred to as a second phase modulation region) of the second electro-optical phase shifter 23 through the second traveling wave electrode, and change the refractive index of the second phase modulation region by changing the carrier concentration in the waveguide of the second phase modulation region, thereby performing a second phase modulation on the optical signal passing through the second phase modulation region.
  • first phase modulation and the second phase modulation may be the same or different.
  • first phase modulation and the second phase modulation may be set according to factors such as the optical fiber link and the transmission distance so that the optical signal received by the receiving device has better quality.
  • the first inverter 24 and the second inverter 25 may be structures for transmitting the optical signal in reverse direction.
  • the first inverter 24 may be a first reflector, a first waveguide loopback or a first grating structure
  • the second inverter 25 may be a second reflector, a second waveguide loopback or a second grating structure.
  • first inverter 24 and the second inverter 25 can be independent structures, for example, the first inverter 24 and the second inverter 25 are two independent reflectors respectively; or, the first inverter 24 and the second inverter 25 can also be an integrated structure, for example, the first inverter 24 and the second inverter 25 are the same reflector.
  • FIG4 is a schematic diagram of the structure of the optical modulator provided in Example 2 of the present application.
  • the optical modulator 30 may include: a combiner/splitter 21, a first electro-optical phase shifter 22 and a second electro-optical phase shifter 23 connected to the combiner/splitter 21, a first inverter 24 connected to the first electro-optical phase shifter 22, a second inverter 25 connected to the second electro-optical phase shifter 23, and a micro-ring resonator array 26 connected to the combiner/splitter 21.
  • the optical modulator 30 shown in FIG4 also includes a micro-ring resonator array 26. Except for this difference, the other contents can refer to the description in Example 1.
  • the microring resonator array 26 is used to perform delay compensation processing on the modulated optical signal output by the combiner/splitter 21.
  • optical signals of different wavelengths can be subjected to different degrees of delay compensation, so as to further enhance the dispersion compensation effect (that is, the dispersion can be compensated by setting unequal splitting ratios and microring resonator arrays), which is convenient for balancing the dispersion caused by the transmission link.
  • the microring resonator array 26 may include a microring resonator (also referred to as a microring), or may include multiple microring resonators.
  • the microring resonator array 26 includes multiple microring resonators, the multiple microring resonators may be connected in series or in parallel, without specific limitation.
  • the microring resonator array 26 includes a microring, and the microring may be a thermally adjustable microring; that is, the delay imposed by the microring on the optical signal may be adjusted by controlling the temperature.
  • FIG5 is a schematic diagram of the structure of a transmitting device provided in Embodiment 3 of the present application.
  • the transmitting device 50 includes one or more optical modulators.
  • FIG5 shows two optical modulators (i.e., optical modulator 51 and optical modulator 52) included in the transmitting device 50, wherein the optical modulator 51 or the optical modulator 52 may be the optical modulator 20 in Embodiment 1 above, or may also be the optical modulator 30 in Embodiment 2 above.
  • the optical modulator 51 and the optical modulator 52 can work independently.
  • the optical modulator 51 can modulate the optical signal of the first wavelength (such as 1331nm) and output the modulated optical signal
  • the optical modulator 52 can modulate the optical signal of the second wavelength (such as 1351nm) and output the modulated optical signal.
  • FIG6 is another schematic diagram of the structure of the transmitting device provided in the third embodiment of the present application.
  • the transmitting device 60 includes a beam splitter 61 and N optical modulators connected to the beam splitter 61.
  • the optical modulator 62 or the optical modulator 63 can be the optical modulator 20 in the above-mentioned embodiment 1, or can also be the optical modulator 30 in the above-mentioned embodiment 2.
  • the beam splitter 61 is used to: split the input optical signal into N optical signals, and input the N optical signals into N optical modulators respectively.
  • the splitting ratios of the N optical signals are the same, that is, the splitting ratio of the N optical signals is 1:1.
  • the beam splitter 61 divides the input optical signal into N optical signals, and the N optical signals enter N optical modulators for phase modulation respectively, and then the N optical modulators can output modulated optical signals respectively.
  • the splitting ratios corresponding to the N optical modulators can be the same or different. When the splitting ratios corresponding to the N optical modulators are different, different transmission distances can be adapted, thereby making signal transmission more flexible.
  • the N optical modulators in the transmitting device can reuse the same input port through a beam splitter, that is, the N optical modulators can modulate the optical signal of the same wavelength and output the modulated optical signal respectively, thereby facilitating improving the integration.
  • FIG. 7 is a schematic diagram of a communication system provided in an embodiment of the present application.
  • a communication system 70 includes a transmitting device 71 (the transmitting device 71 may be the transmitting device 50 illustrated in FIG. 5 or the transmitting device 60 illustrated in FIG. 6), an optical fiber link 72, and a receiving device 73.
  • the optical fiber link 72 connects the transmitting device 71 and the receiving device 73.
  • the modulated optical signal transmitted by the transmitting device 71 will be dispersed after long-distance transmission in the optical fiber link 72, and the optical modulator in the transmitting device can pre-compensate the optical signal and compensate for the dispersion, so that the optical signal received by the receiving device 73 has better quality, so as to realize high-speed, large-capacity, and long-distance communication.
  • FIG8 is a flow chart of a modulation method according to an embodiment of the present application.
  • the modulation method may be performed on an optical signal by the optical modulator in the above-mentioned embodiment 1 or embodiment 2.
  • the modulation method may include:
  • the first optical signal can be transmitted in the reverse direction after undergoing one phase modulation
  • the first optical signal can undergo two phase modulations in the first phase modulation area (i.e., the phase shift of the first optical signal is doubled).
  • the second optical signal can be transmitted in the reverse direction after undergoing one phase modulation, so that the second optical signal can undergo two phase modulations in the second phase modulation area (i.e., the phase shift of the second optical signal is doubled).
  • the length of the phase modulation area can be halved, effectively reducing the size of the optical modulator and improving the integration.
  • a and/or B in the embodiments of the present application describes the association relationship of associated objects, indicating that three relationships may exist, for example, A and/or B, which may represent: the situation where A exists alone, A and B exist at the same time, and B exists alone, wherein A and B may be singular or plural.
  • a and/or B At least one of the following (individuals)” or similar expressions thereof refer to any combination of these items, including any combination of single items (individuals) or plural items (individuals).
  • “at least one of A, B and C” includes A, B, C, AB, AC, BC or ABC.
  • ordinal numbers such as “first” and “second” to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects.
  • references to "one embodiment” or “some embodiments” etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application.
  • the phrases “in one embodiment”, “in another embodiment”, “in some other embodiments”, “in some other embodiments”, etc. appearing in different places in this specification do not necessarily refer to the same embodiment, but mean “one or more but not all embodiments", unless otherwise specifically emphasized in other ways.
  • the terms “including”, “comprising”, “having” and their variations all mean “including but not limited to”, unless otherwise specifically emphasized in other ways.

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Abstract

一种光调制器、发射装置、通信系统及调制方法。光调制器包括合/分束器，与合/分束器连接的第一电光移相器和第二电光移相器，与第一电光移相器连接的第一反向器，与第二电光移相器连接的第二反向器。合/分束器将输入的光信号分为第一光信号和第二光信号，并将第一光信号输入第一电光移相器，将第二光信号输入第二电光移相器；由于设置了第一反向器，使得第一光信号经历过一次相位调制后可以反向传输，实现第一光信号在第一电光移相器中的相位调制区来回经历两次相位调制；第二反向器也是类似。相比于传统的光调制器来说，光调制器中第一电光移相器和第二电光移相器中的相位调制区的长度可以减半，从而有效缩小光调制器的尺寸，提高集成度。

Description

光调制器、发射装置、通信系统及调制方法 技术领域
本申请涉及通信技术领域，尤其涉及一种光调制器、发射装置、通信系统及调制方法。
背景技术
随着通信技术的迅速发展，现代通信对信息大容量与高速化的需求不断提高，光作为一种高速、高带宽、多维度的传输媒介，使得光通信技术迅猛发展。光调制器是光通信领域的重要有源器件，并被广泛应用于光收发模块产品中，其工作方式是将高低变化的电压调制信号转化为强弱变化的光强度调制信号。比如，光调制器为马赫增德尔调制器(Mach-Zehnder modulator，MZM)。
然而，由于光调制器的尺寸一般比较大，如硅基MZM一般在1～3毫米(mm)长，铌酸锂MZM的长度一般在1厘米(cm)左右，从而会导致集成度不足，不利于小型化发展。
发明内容
本申请提供了一种光调制器、发射装置、通信系统及调制方法，用于降低光调制器的尺寸，便于提高集成度。
第一方面，本申请提供了一种光调制器，该光调制器可以包括：合/分束器，与合/分束器连接的第一电光移相器和第二电光移相器，与第一电光移相器连接的第一反向器，与第二电光移相器连接的第二反向器。
上述光调制器工作时，所述合/分束器用于将输入的光信号分为第一光信号和第二光信号，并将第一光信号输入所述第一电光移相器，将第二光信号输入所述第二电光移相器；
所述第一电光移相器用于对所述第一光信号进行第一相位调制得到第一调制光信号，并将所述第一调制光信号输入所述第一反向器；所述第一反向器用于将所述第一调制光信号的传输方向由第一传输方向调整为第二传输方向，所述第二传输方向与所述第一传输方向相反，以使所述第一调制光信号输入所述第一电光移相器；所述第一电光移相器还用于对所述第一调制光信号进行所述第一相位调制，得到第二调制光信号，并将所述第二调制光信号输入所述合/分束器；
所述第二电光移相器用于对所述第二光信号进行第二相位调制得到第三调制光信号，并将所述第三调制光信号输入所述第二反向器；所述第二反向器用于将所述第三调制光信号的传输方向由第三传输方向调整为第四传输方向，所述第四传输方向与所述第三传输方向相反，以使所述第三调制光信号输入所述第二电光移相器；所述第二电光移相器还用于对所述第三调制光信号进行所述第二相位调制，得到第四调制光信号，并将所述第四调制光信号输入所述合/分束器；
所述合/分束器还用于对所述第二调制光信号和所述第四调制光信号进行合束，形成调制光信号，并输出所述调制光信号。
如此，由于光调制器中设置了第一反向器，从而使得第一光信号经历过一次相位调制后可以反向传输，实现第一光信号在第一电光移相器中的相位调制区来回经历两次相位调 制(即第一光信号的相移量翻倍)。同样地，由于光调制器中设置了第二反向器，从而使得第二光信号经历过一次相位调制后可以反向传输，实现第二光信号在第二电光移相器中的相位调制区来回经历两次相位调制(即第二光信号的相移量翻倍)。而传统的光调制器中，光信号在调制臂的相位调制区仅经历一次相位调制。因此，相比于传统的光调制器来说，光调制器中第一电光移相器和第二电光移相器中的相位调制区的长度可以减半，从而可以有效缩小光调制器的尺寸，提高集成度。
在一种可能的设计中，所述第一反向器为第一反射镜、第一波导回环器或第一光栅结构；所述第二反向器为第二反射镜、第二波导回环器或第二光栅结构。
在一种可能的设计中，所述第一光信号和第二光信号的分光比例为1：m，m>0且m≠1。也就是说，合/分束器可以对输入的光信号进行非等比例的分光。如此，后续对第一光信号和第二光信号分别进行相位调制后，由于第一光信号和第二光信号为非等比例，第一光信号与第二光信号合束之后，第一光信号的相位偏移与第二光信号的相位偏移不会完全抵消。因此，相比于输入的光信号，最终输出的光信号会叠加有额外的相位调制，从而可以实现预补偿。
在一种可能的设计中，所述合/分束器为多模干涉仪。
在一种可能的设计中，所述光调制器还包括与所述合/分束器连接的微环谐振器阵列；所述微环谐振器阵列用于对所述合/分束器输出的调制光信号进行延时补偿处理。
如此，通过设置微环谐振器阵列对光调制信号进行延时补偿处理，便于与传输链路带来的色散相平衡。
第二方面，本申请实施例提供一种发射装置，所述发射装置包括上述第一方面的任一种可能的设计中所述的光调制器。
第三方面，本申请实施例提供一种发射装置，所述发射装置包括：分束器，与所述分束器连接的N个光调制器；其中，所述分束器用于：将输入的光信号分为N个光信号，将所述N个光信号分别输入所述N个光调制器；所述N个光调制器中的第i光调制器用于：对所述N个光信号中的第i光信号进行相位调制，并输出第i调制光信号；其中，i＝1,2,……N，N为大于1的整数。
在一种可能的设计中，所述N个光信号的分光比例相同。
在一种可能的设计中，所述N个光调制器包括上述第一方面的任一种可能的设计中所述的光调制器。
第四方面，本申请实施例提供一种通信系统，该通信系统包括接收装置、光纤链路和第二方面或第三方面所述的发射装置，光纤链路连接发射装置和接收装置。
第五方面，本申请实施例提供一种调制方法，该方法可以应用于上述第一方面的光调制器。该方法包括：将输入的光信号分为第一光信号和第二光信号；在第一相位调制区对所述第一光信号进行第一相位调制得到第一调制光信号；以及，将所述第一调制光信号的传输方向由第一传输方向调整为第二传输方向，所述第二传输方向与所述第一传输方向相反，以使所述第一调制光信号传输至所述第一相位调制区；在所述第一相位调制区对所述第一调制光信号进行所述第一相位调制，得到第二调制光信号；在第二相位调制区对所述第二光信号进行第二相位调制得到第三调制光信号；以及，将所述第三调制光信号的传输方向由第三传输方向调整为第四传输方向，所述第四传输方向与所述第三传输方向相反，以使所述第三调制光信号传输至所述第二相位调制区；在所述第二相位调制区对所述第三 调制光信号进行所述第二相位调制，得到第四调制光信号；对所述第二调制光信号和所述第四调制光信号进行合束，形成调制光信号，并输出所述调制光信号。
附图说明
图1为本申请实施例提供的波分复用示意图；
图2为本申请实施例提供的一种传统的光调制器(比如MZM)示意图；
图3为本申请实施例一提供的光调制器的结构示意图；
图4为本申请实施例二提供的光调制器的结构示意图；
图5为本申请实施例三提供的发射装置的一种结构示意图；
图6为本申请实施例三提供的发射装置的又一种结构示意图；
图7为本申请实施例中提供的通信系统示意图；
图8为本申请实施例提供的调制方法所对应的流程示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。
随着通信技术的飞速发展，移动用户数量及业务量高速增长，无线接入网设备(比如基站)的数量急剧增加。为了优化网络架构，在无线前传场景中，集中式无线接入网(centralized radio access network，C-RAN)成为主流的应用，C-RAN网络架构可实现基带处理单元(building base band unit，BBU)集中管理，BBU和射频单元之间通过光纤连接，射频单元比如为远端射频单元(remote radio unit，RRU)。
由于BBU和RRU之间的距离一般较远，为了节约光纤资源，可以采用波分复用(wavelength division multiplexing，WDM)技术实现光纤复用。如图1所示，多个射频单元可以通过波分设备复用一根光纤与BBU连接，从而提高光纤利用率。此外，通过同一波分设备进行光纤复用的射频单元所连接的主光纤(位于射频单元侧的波分设备和BBU侧的波分设备之间的光纤)相同，仅在射频单元侧的波分设备到各射频单元之间的尾纤长度可能存在差别。
其中，WDM技术也可以称为光波复用技术，是一种在发送端将两种或多种不同波长的光信号经复用器(multiplexer)汇合在一起，并耦合到同一根光纤中进行发送，在接收端经解复用器(de-multiplexer)将各种波长的光信号分离的数据传输技术。基本原理是将不同的光信号由不同的颜色(波长频率)承载，然后复用在一根光纤上传输。常用的波分复用包括稀疏波分复用(coarse wavelength division multiplexing，CWDM)、密集波分复用(dense wavelength division multiplexing，DWDM)、细波分复用(lan-wavelength division multiplexing，LWDM)等。
波分设备是一种采用WDM技术支持两种或多种不同波长的光信号在一根光纤中进行传输的设备，比如波分设备可以是CWDM波分设备、DWDM波分设备、LWDM波分设备等。波分设备可以对射频单元和BBU的光模块波长进行规范，其中不同波分设备对射频单元和BBU端口的光模块波长的规范不同。以波分设备为6波的CWDM波分设备为例，根据6波的CWDM波分设备对光模块波长规范，射频单元的光模块波长可以为1271、1291或1311(单位：纳米(nm))，BBU的光模块波长可以为1331、1351或1371(单位：纳 米)。
以BBU发送信号为例，BBU的光模块中可以包括3个光调制器，3个光调制分别对三种波长(即1331或1351或1371nm)的光信号进行调制，并将调制后的光信号输入至波分设备，进而由波分设备将三种波长的光信号通过一根光纤传输给不同的射频单元。
图2为一种传统的光调制器(比如MZM)示意图。如图2所示，传统的光调制器10可以包括：分束器11，设置在分束器11的每个分支上的调制臂。参考图2所示，在具体设置时，分束器11的分支个数为两个，两个分支对称设置，即两个调制臂(调制臂12和调制臂13)对称设置。进一步地，传统的光调制器10还包括：与两个调制臂连接的合束器14。
具体实施时，分束器11接收到输入的光信号后，将光信号分为功率相等的两束光或者说两个光信号(即两个光信号的分光比为1:1)，比如两个光信号分别为光信号a和光信号b，并将光信号a输入调制臂12，将光信号b输入调制臂13。进而，调制臂12对光信号a进行相位调制，得到调制后的光信号a，并将调制后的光信号a输入合束器14；调制臂13对光信号b进行相位调制，得到调制后的光信号b，并将调制后的光信号b输入合束器14。合束器14对调制后的光信号a和调整后的光信号b进行合束，并输出合束后的光信号。
其中，传统的光调制器是利用光学干涉原理将相位调制转换强度调制。具体来说，当两个调制臂输出的两束光的相位相同时，根据光的干涉理论，合束时干涉相长，输出的光强最大，可以看作是高电平信号；当两个调制臂输出的两束光存在相位差时，合束发生干涉后，光强不是最大值，若相位差为π，干涉相消，输出光强最小，可以看作是低电平信号。如此，根据两束光的相位差形成光强的相消或者相长，从而形成强弱变化，实现对光信号的调制。
然而，由于传统的光调制器的尺寸一般比较大，以铌酸锂MZM为例，铌酸锂MZM通过钛扩散或质子交换工艺对单晶铌酸锂材料进行局部掺杂构成波导，波导的芯层和包层之间的折射率差很小，波导对光场的束缚能力差，同时为了达到低驱动电压的性能，相位调制区的长度需要设计的很长，这使得封装后的光调制器尺寸较大，从而会导致集成度不足，不利于小型化发展。
基于此，本申请实施例对传统的光调制器的结构进行改进，通过在光调制器中引入反向器，使得光信号可以在相位调制区来回经历两次相位调制，便于缩小相位调制区的长度，进而缩小光调制器的尺寸，提高集成度。
示例性地，本申请实施例提供的光调制器可以制作在芯片上，或者也可以直接装配在光模块中。本申请实施例提供的光调制器可以应用于无线前传、中回传、数据中心、接入网或骨干网等通信场景的通信设备中；比如，本申请实施例提供的光调制器可以应用于上述BBU(比如装配在BBU的光模块中)。
实施例一
图3为本申请实施例一提供的光调制器的结构示意图。如图3所示，光调制器20可以包括：合/分束器21，与合/分束器21连接的第一电光移相器22和第二电光移相器23(即第一电光移相器22和第二电光移相器23位于合/分束器21的两个分支上)，与第一电光移相器22连接的第一反向器24，与第二电光移相器23连接的第二反向器25。
合/分束器21用于：将输入的光信号分为第一光信号和第二光信号，并将第一光信号输入第一电光移相器22，将第二光信号输入第二电光移相器23。比如，合/分束器21的输入端可以连接激光器，激光器用于向合/分束器21输入光信号。作为一种可能的实现，激光器可以为连续(continuous wave，CW)激光器。
第一电光移相器22用于：对第一光信号进行第一相位调制得到第一调制光信号，并将第一调制光信号输入第一反向器24。
第一反向器24用于：将第一调制光信号的传输方向由第一传输方向调整为第二传输方向，第二传输方向与第一传输方向相反，以使第一调制光信号输入第一电光移相器22。
第一电光移相器22还用于：对第一调制光信号进行第一相位调制，得到第二调制光信号，并将第二调制光信号输入合/分束器21。
第二电光移相器23用于：对第二光信号进行第二相位调制得到第三调制光信号，并将第三调制光信号输入第二反向器25。
第二反向器25用于：将第三调制光信号的传输方向由第三传输方向调整为第四传输方向，第四传输方向与第三传输方向相反，以使第三调制光信号输入第二电光移相器23。
第二电光移相器23还用于：对第三调制光信号进行第二相位调制，得到第四调制光信号，并将第四调制光信号输入合/分束器21。
合/分束器21还用于：对第二调制光信号和第四调制光信号进行合束，形成调制光信号，并输出调制光信号。
如此，一方面，由于光调制器20中设置了第一反向器24，从而使得第一光信号经历过一次相位调制后可以反向传输，实现第一光信号在第一电光移相器22中的相位调制区来回经历两次相位调制(即第一光信号的相移量翻倍)。同样地，由于光调制器20中设置了第二反向器25，从而使得第二光信号经历过一次相位调制后可以反向传输，实现第二光信号在第二电光移相器23中的相位调制区来回经历两次相位调制(即第二光信号的相移量翻倍)。而传统的光调制器10中，光信号在调制臂的相位调制区仅经历一次相位调制。因此，相比于传统的光调制器10来说，光调制器20中第一电光移相器22和第二电光移相器23中的相位调制区的长度可以减半，从而可以有效缩小光调制器的尺寸，提高集成度。
此外，当第一电光移相器22和第二电光移相器23中的相位调制区的长度减半时，可以有效降低电信号损耗(相位调制区的长度越长，电信号损耗越大)，从而便于降低对第一电光移相器22和第二电光移相器23中的驱动电信号的幅值要求。
又一方面，光调制器20中的光口(即光信号的输入端口和调制光信号的输出端口)均位于合/分束器21，即光信号的输入端口和调制光信号的输出端口在同一侧；而传统的光调制器10中，光信号的输入端口位于分束器11，调制光信号的输出端口位于合束器14，即光信号的输入端口和调制光信号的输出端口位于调制臂的两侧。因此，相比于传统的光调制器10来说，光调制器20将光口设置在同一侧可以降低走线损耗，降低光口耦合难度和光纤阵列(fiber array，FA)数量。
下面分别对光调制器20所包括的各个器件进行描述。
(1)合/分束器21
示例性地，合/分束器21可以为多模干涉仪(multi-mode interferometer，MMI)，比如合/分束器21为2*2MMI。其中，2*2MMI的一侧具有两个端口，分别为端口1和端口2， 相对应的另一侧也具有两个端口，分别为端口3和端口4。端口1用于输入光信号，端口2用于输出调制光信号，端口3用于输出第一光信号，端口4用于输出第二光信号。
比如，具体实施中，可以通过调整光调制器20的工作点和/或第一电光移相器22的相位调制区和第二电光移相器23的相位调制区的长度差，来控制第二调制光信号和第四调制光信号的直流相位差，以便于第二调制光信号和第四调制光信号合束后的调制光信号可以从2*2MMI的另一个端口输出，不会对输入端口形成倒灌。
可以理解的是，在其它可能的实施例中，合/分束器21也可以为其它可能的干涉仪，比如马赫增德尔干涉仪(Mach-Zehnder interferometer，MZI)，具体不做限定。
作为一种可能的实现，合/分束器21可以将输入的光信号按照1:m的分光比分为第一光信号和第二光信号，其中，m>0且m≠1。也就是说，合/分束器21可以对输入的光信号进行非等比例的分光。如此，后续对第一光信号和第二光信号分别进行相位调制后，由于第一光信号和第二光信号为非等比例，第一光信号与第二光信号合束之后，第一光信号的相位偏移与第二光信号的相位偏移不会完全抵消。因此，相比于输入的光信号，最终输出的光信号会叠加有额外的相位调制，从而可以实现预补偿。
可以理解的是，本申请实施例中所描述的预补偿可以发生在光纤链路之前，也就是说，光信号在发生色散之前已经被调制，例如光调制器20设置在发射装置侧，即在发射装置侧对光信号进行的相位调制。因此，当光调制器20输出的光信号进入光纤链路后，即使光信号在光纤链路中发生色散，由于光信号进入光纤链路已经进行了预补偿，从而可以有效减少色散带来的问题。
下面利用数学推导对本申请的光调制器20对光信号的色散补偿进行详细说明。
在本申请的光调制器20中，第一光信号的电场为：
E 1＝Ae ix(t)                 (1)
第二光信号的电场为：
E 2＝Be -ix(t)                  (2)
其中，x(t)表示复合信号。在本申请的光调制器20中，x(t)表示真实信号s(t)和直流偏置b(不同的直流偏置对应不同的工作点)共同作用后的复合信号，即：
x(t)＝s(t)+b              (3)
上述公式(1)和(2)中，A为合/分束器21输出的第一光信号对应的分量，B为合/分束器21输出的第二光信号对应的分量。A、B和m满足：A:B＝1:m。当m＝1时，A＝B。此外，A和B还满足：
A 2+B 2＝1              (4)
根据上述公式(1)、(2)、(3)和(4)，第一光信号与第二光信号合束之后的电场为：
E＝E 1+E 2＝(A+B)cosx(t)+i(A-B)sinx(t)         (5)
由于工作点选取在线性区(在线性区域内，由于电信号与光信号的映射函数关系为简单线性关系，电信号所携带的信息调制到光信号中后，信息不会发生变化与失真。由于光调制器的直流偏置电压与输出光功率的关系类似于一个sin曲线，因此，如果工作点选取在sin曲线中间的位置(如sin0，sinπ的位置)，则认为是光调制器是工作在线性区域内)，故上述公式(5)可以近似为：
E＝(A+B)x(t)+i(A-B)x(t)              (6)
当光调制器20应用于通信系统时，以光信号在10km长的光纤链路中传输为示例。假 设色散效应产生的传递函数为h，则接收装置接收到的光信号的电场为：
Figure PCTCN2022134808-appb-000001
根据上述公式(7)，接收装置接收到的光信号的强度为：
Figure PCTCN2022134808-appb-000002
忽略上述公式(8)中的常数项，可得：
Figure PCTCN2022134808-appb-000003
上述公式(9)中，由于高阶项为前项近似产生的误差，可忽略。因此，将I(t)进行快速傅立叶变换(fast fourier transform，FFT)，并且带入以下公式：
H(ω)＝cos(ω 2βL/2)+isin(ω 2βL/2)            (10)
可得：
I(ω)＝8ABb*S(ω)*cos(ω 2βL/2)+4(A 2-B 2)b*S(ω)*sin(ω 2βL/2)    (11)
当合/分束器21的分光比为1时，m＝1且A＝B，则I(ω)＝8ABb*S(ω)*cos(ω 2βL/2)，光信号会经历由色散带来的cos滤波效应。
当合/分束器21的分光比不等于1时，m≠1，即A≠B。此时，I(ω)中的4(A 2-B 2)b*S(ω)*sin(ω 2βL/2)部分不为零，可以实现色散补偿，并且根据A和B的相对大小，可以控制光信号的正补偿方向或负补偿方向。
(2)第一电光移相器22、第二电光移相器23
示例性地，第一电光移相器22可以包括第一行波电极，第一电光移相器22可以通过第一行波电极将高速电信号加载到第一电光移相器22的相位调制区(称为第一相位调制区)，通过改变第一相位调制区的波导中的载流子浓度来改变第一相位调制区的折射率，从而对经过第一相位调制区的光信号进行第一相位调制。
第二电光移相器23可以包括第二行波电极，第二电光移相器23可以通过第二行波电极将高速电信号加载到第二电光移相器23的相位调制区(称为第二相位调制区)，通过改变第二相位调制区的波导中的载流子浓度来改变第二相位调制区的折射率，从而对经过第二相位调制区的光信号进行第二相位调制。
可以理解的是，第一相位调制和第二相位调制可以相同，或者也可以不同。在实际应用中，可以根据光纤链路、传输距离等因素来设置第一相位调制和第二相位调制，使接收装置接收到的光信号质量较佳。
(3)第一反向器24、第二反向器25
第一反向器24和第二反向器25可以为使光信号反向传输的结构。比如，第一反向器24可以为第一反射镜、第一波导回环器或第一光栅结构，第二反向器25可以为第二反射镜、第二波导回环器或第二光栅结构。
可以理解的是，第一反向器24和第二反向器25可以为独立的结构，比如第一反向器24和第二反向器25分别为两个独立的反射镜；或者，第一反向器24和第二反向器25也可以为一体的结构，比如第一反向器24和第二反向器25为同一个反射镜。
实施例二
图4为本申请实施例二提供的光调制器的结构示意图。如图4所示，光调制器30可以包括：合/分束器21，与合/分束器21连接的第一电光移相器22和第二电光移相器23，与第一电光移相器22连接的第一反向器24，与第二电光移相器23连接的第二反向器25，与合/分束器21连接的微环谐振器阵列26。图4所示意的光调制器30相比于图2所示意的光调制器20来说，光调制器30还包括微环谐振器阵列26，除此区别之外的其它内容，均可以参照实施例一中的描述的。
在光调制器30中，微环谐振器阵列26用于对合/分束器21输出的调制光信号进行延时补偿处理。其中，不同波长的光信号可以被施加不同程度的延时补偿，从而可以进一步强化色散补偿效果(即可以通过设置不等分光比和微环谐振器阵列来对色散进行补偿)，便于与传输链路带来的色散相平衡。
示例性地，微环谐振器阵列26可以包括一个微环谐振器(也可以简称微环)，或者也可以包括多个微环谐振器。当微环谐振器阵列26包括多个微环谐振器时，这多个微环谐振器可以串联或者也可以并联，具体不做限定。以微环谐振器阵列26包括一个微环为例，该微环可以为热调微环；也就是说，可以通过控制温度来调整微环对光信号所施加的延时。
实施例三
图5为本申请实施例三提供的发射装置的一种结构示意图。如图5所示，发射装置50包括一个或多个光调制器。图5中示出了发射装置50所包括的两个光调制器(即光调制器51和光调制器52)，其中，光调制器51或光调制器52可以为上述实施例一中的光调制器20，或者也可以为上述实施例二中光调制器30。
光调制器51和光调制器52可以独立工作，比如光调制器51可以对第一种波长(比如1331nm)的光信号进行调制，并输出调制后的光信号；光调制器52可以对第二种波长(比如1351nm)的光信号进行调制，并输出调制后的光信号。
图6为本申请实施例三提供的发射装置的又一种结构示意图。如图6所示，发射装置60包括分束器61，与分束器61连接的N个光调制器。图6中是以N＝2为例进行示意的，N个光调制器分别为光调制器62和光调制器63。其中，光调制器62或光调制器63可以为上述实施例一中的光调制器20，或者也可以为上述实施例二中光调制器30。
分束器61用于：将输入的光信号分为N个光信号，将N个光信号分别输入N个光调制器。N个光调制器中的第i光调制器用于：对N个光信号中的第i光信号进行相位调制，并输出第i调制光信号；其中，i＝1,2,……N，N为大于1的整数。示例性地，N个光信号的分光比例相同，即N个光信号的分光比为1:1。
也就是说，分束器61将输入的光信号分为N个光信号，N个光信号分别进入N个光调制器进行相位调制，进而N个光调制器可以分别输出调制后的光信号。其中，N个光调制器对应的分光比可以相同，或者也可以不同，当N个光调制器对应的分光比不同时，可以适配不同的传输距离，从而使得信号传输更加灵活。
采用上述图6所示意的结构，发射装置中的N个光调制器可以通过分束器复用同一个输入端，即N个光调制器可以对同一种波长的光信号进行调制，并分别输出调制后的光信号，从而便于提高集成度。
基于图5或6所示意的发射装置，本申请实施例还提供一种通信系统。图7为本申请 实施例中提供的通信系统示意图，如图7所示，通信系统70包括发射装置71(发射装置71可以为图5所示意的发射装置50或图6所示意的发射装置60)、光纤链路72和接收装置73。其中，光纤链路72连接发射装置71和接收装置73。在该通信系统70中，发射装置71发射的调制光信号在光纤链路72中经过长距传输后会发生色散现象，而发射装置中的光调制器可以对光信号进行的预补偿可以对色散进行补偿，从而使接收装置73接收到的光信号质量较佳，以实现高速度、大容量、长距离的通信。
实施例四
图8为本申请实施例提供的调制方法所对应的流程示意图，本申请实施例中可以通过上述实施例一或实施例二中的光调制器对光信号执行调制方法。如图8所示，调制方法可以包括：
S801，将输入的光信号分为第一光信号和第二光信号。
S802-a，在第一相位调制区对第一光信号进行第一相位调制得到第一调制光信号。
S803-a，将第一调制光信号的传输方向由第一传输方向调整为第二传输方向，第二传输方向与第一传输方向相反，以使第一调制光信号传输至第一相位调制区。
S804-a，在第一相位调制区对第一调制光信号进行第一相位调制，得到第二调制光信号。
S802-b，在第二相位调制区对第二光信号进行第二相位调制得到第三调制光信号。
S803-b，将第三调制光信号的传输方向由第三传输方向调整为第四传输方向，第四传输方向与第三传输方向相反，以使第三调制光信号传输至第二相位调制区。
S804-b，在第二相位调制区对第三调制光信号进行第二相位调制，得到第四调制光信号。
S805，对第二调制光信号和第四调制光信号进行合束，形成调制光信号，并输出调制光信号。
采用上述方法，由于对第一光信号经历过一次相位调制后可以反向传输，实现第一光信号在第一相位调制区来回经历两次相位调制(即第一光信号的相移量翻倍)。同样地，第二光信号经历过一次相位调制后可以反向传输，实现第二光信号在第二相位调制区来回经历两次相位调制(即第二光信号的相移量翻倍)。从而使得相位调制区的长度可以减半，有效缩小光调制器的尺寸，提高集成度。
本申请实施例中的术语“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A、同时存在A和B、单独存在B的情况，其中A，B可以是单数或者复数。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如“A，B和C中的至少一个”包括A，B，C，AB，AC，BC或ABC。以及，除非有特别说明，本申请实施例提及“第一”、“第二”等序数词是用于对多个对象进行区分，不用于限定多个对象的顺序、时序、优先级或者重要程度。
在本说明书中描述的参考“一个实施例”或“一些实施例”等意味着在本申请的一个或多个实施例中包括结合该实施例描述的特定特征、结构或特点。由此，在本说明书中的不同之处出现的语句“在一个实施例中”、“在另一个实施例中”、“在一些实施例中”、“在其他一些实施例中”、“在另外一些实施例中”等不是必然都参考相同的实施例，而是意味着“一个 或多个但不是所有的实施例”，除非是以其他方式另外特别强调。术语“包括”、“包含”、“具有”及它们的变形都意味着“包括但不限于”，除非是以其他方式另外特别强调。
以上，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，可轻易想到变化或替换，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。
显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (11)

  1. 一种光调制器，其特征在于，所述光调制器包括：合/分束器，与合/分束器连接的第一电光移相器和第二电光移相器，与第一电光移相器连接的第一反向器，与第二电光移相器连接的第二反向器；
    所述合/分束器用于：将输入的光信号分为第一光信号和第二光信号，并将第一光信号输入所述第一电光移相器，将第二光信号输入所述第二电光移相器；
    所述第一电光移相器用于：对所述第一光信号进行第一相位调制得到第一调制光信号，并将所述第一调制光信号输入所述第一反向器；
    所述第一反向器用于：将所述第一调制光信号的传输方向由第一传输方向调整为第二传输方向，所述第二传输方向与所述第一传输方向相反，以使所述第一调制光信号输入所述第一电光移相器；
    所述第一电光移相器还用于：对所述第一调制光信号进行所述第一相位调制，得到第二调制光信号，并将所述第二调制光信号输入所述合/分束器；
    所述第二电光移相器用于：对所述第二光信号进行第二相位调制得到第三调制光信号，并将所述第三调制光信号输入所述第二反向器；
    所述第二反向器用于：将所述第三调制光信号的传输方向由第三传输方向调整为第四传输方向，所述第四传输方向与所述第三传输方向相反，以使所述第三调制光信号输入所述第二电光移相器；
    所述第二电光移相器还用于：对所述第三调制光信号进行所述第二相位调制，得到第四调制光信号，并将所述第四调制光信号输入所述合/分束器；
    所述合/分束器还用于：对所述第二调制光信号和所述第四调制光信号进行合束，形成调制光信号，并输出所述调制光信号。
  2. 根据权利要求1所述的光调制器，其特征在于，所述第一反向器为第一反射镜、第一波导回环器或第一光栅结构；
    所述第二反向器为第二反射镜、第二波导回环器或第二光栅结构。
  3. 根据权利要求1或2所述的光调制器，其特征在于，所述第一光信号和第二光信号的分光比例为1：m，m>0且m≠1。
  4. 根据权利要求1至3中任一项所述的光调制器，其特征在于，所述合/分束器为多模干涉仪。
  5. 根据权利要求1至4中任一项所述的光调制器，其特征在于，所述光调制器还包括与所述合/分束器连接的微环谐振器阵列；
    所述微环谐振器阵列用于对所述合/分束器输出的调制光信号进行延时补偿处理。
  6. 一种发射装置，其特征在于，所述发射装置包括如权利要求1至5任一项所述的光调制器。
  7. 一种发射装置，其特征在于，所述发射装置包括：分束器，与所述分束器连接的N个光调制器；
    所述分束器用于：将输入的光信号分为N个光信号，将所述N个光信号分别输入所述N个光调制器；
    所述N个光调制器中的第i光调制器用于：对所述N个光信号中的第i光信号进行相 位调制，并输出第i调制光信号；其中，i＝1,2,……N，N为大于1的整数。
  8. 根据权利要求7所述的发射装置，其特征在于，所述N个光信号的分光比例相同。
  9. 根据权利要求7或8所述的发射装置，其特征在于，所述N个光调制器包括如权利要求1至5任一项所述的光调制器。
  10. 一种通信系统，其特征在于，包括接收装置、光纤链路和如权利要求6至9中任一项所述的发射装置，所述光纤链路连接所述发射装置和所述接收装置。
  11. 一种调制方法，其特征在于，所述方法包括：
    将输入的光信号分为第一光信号和第二光信号；
    在第一相位调制区对所述第一光信号进行第一相位调制得到第一调制光信号；以及，将所述第一调制光信号的传输方向由第一传输方向调整为第二传输方向，所述第二传输方向与所述第一传输方向相反，以使所述第一调制光信号传输至所述第一相位调制区；在所述第一相位调制区对所述第一调制光信号进行所述第一相位调制，得到第二调制光信号；
    在第二相位调制区对所述第二光信号进行第二相位调制得到第三调制光信号；以及，将所述第三调制光信号的传输方向由第三传输方向调整为第四传输方向，所述第四传输方向与所述第三传输方向相反，以使所述第三调制光信号传输至所述第二相位调制区；在所述第二相位调制区对所述第三调制光信号进行所述第二相位调制，得到第四调制光信号；
    对所述第二调制光信号和所述第四调制光信号进行合束，形成调制光信号，并输出所述调制光信号。
PCT/CN2022/134808 2022-11-28 2022-11-28 光调制器、发射装置、通信系统及调制方法 WO2024113118A1 (zh)

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Publication number Priority date Publication date Assignee Title
CN109946790A (zh) * 2017-12-20 2019-06-28 中兴光电子技术有限公司 一种光偏振调制器及光偏振调制的方法
CN109981182A (zh) * 2019-03-06 2019-07-05 电子科技大学 一种四相位反射式相干光通信系统
CN111474801A (zh) * 2020-03-31 2020-07-31 华为技术有限公司 光电调制芯片、光组件、光模块和光网络设备
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CN109946790A (zh) * 2017-12-20 2019-06-28 中兴光电子技术有限公司 一种光偏振调制器及光偏振调制的方法
CN109981182A (zh) * 2019-03-06 2019-07-05 电子科技大学 一种四相位反射式相干光通信系统
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