CN111211841B - Double-arm driving four-stage pulse amplitude modulator and modulation method thereof - Google Patents
Double-arm driving four-stage pulse amplitude modulator and modulation method thereof Download PDFInfo
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- CN111211841B CN111211841B CN201911330396.5A CN201911330396A CN111211841B CN 111211841 B CN111211841 B CN 111211841B CN 201911330396 A CN201911330396 A CN 201911330396A CN 111211841 B CN111211841 B CN 111211841B
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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
- H04B10/516—Details of coding or modulation
- H04B10/524—Pulse modulation
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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
- H04B10/516—Details of coding or modulation
- H04B10/5161—Combination of different modulation schemes
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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
- H04B10/516—Details of coding or modulation
- H04B10/54—Intensity modulation
- H04B10/541—Digital intensity or amplitude modulation
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Abstract
The embodiment of the invention provides a four-stage pulse amplitude modulator driven by two arms and a modulation method thereof, relates to the technical field of communication, and can avoid additionally increasing an electric attenuator. The modulation method comprises the following steps: inputting an optical signal; the optical signal is divided into a first sub optical signal and a second sub optical signal, the first sub optical signal enters the upper modulation arm, the second sub optical signal enters the lower modulation arm, and simultaneously, a first driving signal is synchronously input to the upper arm driving electrode and a second driving signal is synchronously input to the lower arm driving electrode; wherein the intensity of the first sub optical signal is different from the intensity of the second sub optical signal; the rising edge or the falling edge of the second driving signal is synchronous with the rising edge or the falling edge of the first driving signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal; and performing pulse modulation on the first sub optical signal by using the first driving signal, performing pulse modulation on the second sub optical signal by using the second driving signal, and outputting a PAM-4 optical signal which is obtained by modulating the first sub optical signal and the second sub optical signal and is coupled and superposed.
Description
Technical Field
The invention relates to the technical field of communication, in particular to a four-level pulse amplitude modulator driven by two arms and a modulation method thereof.
Background
In recent years, the demand for high-rate, high-volume communications has been driven by cloud computing and internet media-based applications, and thus faster, cheaper, short optical interconnects have become a focus of attention.
Short optical interconnections used in data centers are very sensitive to cost and occupied space, and an On-Off Keying (OOK) modulation is generally adopted as an effective solution in the current short optical interconnection system.
However, OOK has not met the requirements of the next generation of optical communications at 400Gb/s, as required for electro-optical broadband. Coherent modulation schemes such as Quadrature Phase Shift Keying (QPSK) and Quadrature amplitude modulation (N-QAM) can provide higher spectral efficiency than OKK, but are used for long distance transmission.
Based on the above, a modulator that can meet the requirement of 400Gb/s optical communication and can realize short optical interconnection is a problem to be solved at present.
Disclosure of Invention
The embodiment of the invention provides a four-stage pulse amplitude modulator driven by two arms and a modulation method thereof, which not only improve the spectral efficiency, but also realize high-speed short optical interconnection, avoid additionally adding an electrical attenuator and simplify the structure of the four-stage pulse amplitude modulator driven by two arms.
In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:
in a first aspect, a modulation method for a four-level pulse amplitude modulator driven by two arms is provided, which includes: inputting an optical signal to an input terminal; dividing the optical signal into a first sub optical signal and a second sub optical signal, wherein the first sub optical signal enters an upper modulation arm, the second sub optical signal enters a lower modulation arm, and a first driving signal is synchronously input to an upper arm driving electrode of the upper modulation arm and a second driving signal is synchronously input to a lower arm driving electrode of the lower modulation arm; wherein the intensity of the first sub optical signal is different from the intensity of the second sub optical signal; a rising or falling edge of the second drive signal is synchronized in time with a rising or falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal; and performing pulse modulation on the first sub optical signal by using the first driving signal, performing pulse modulation on the second sub optical signal by using the second driving signal, and outputting a PAM-4 optical signal which is obtained by modulating the first sub optical signal and the second sub optical signal and is coupled and superposed from an output end.
Optionally, before inputting the optical signal to the input end, the modulation method in which the double arms drive the four-stage pulse amplitude modulator further includes: the electric signal driver generates the first driving signal and the third driving signal; the electric signal driver sends the third driving signal to an adjustable electric signal delay line; the adjustable electric signal delay line receives the third driving signal, and performs delay processing on the time sequence of the third driving signal to obtain a second driving signal; the adjustable electrical signal delay line sends the second drive signal to the lower arm drive electrode while an electrical signal driver sends the first drive signal to the upper arm drive electrode.
Optionally, dividing the optical signal into a first sub optical signal and a second sub optical signal includes: splitting the optical signal into the first sub optical signal and the second sub optical signal with a beam splitter.
Optionally, a ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; or the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 1: 4.
In a second aspect, a dual-arm driven four-level pulse amplitude modulator is provided, which comprises a mach-zehnder intensity modulator, wherein the mach-zehnder intensity modulator comprises an input end, an upper modulation arm, a lower modulation arm and an output end; the input end is used for receiving an optical signal and sending the optical signal to the upper modulation arm and the lower modulation arm; the optical signal comprises a first sub optical signal and a second sub optical signal, and the intensity of the first sub optical signal is different from the intensity of the second sub optical signal; an upper arm driving electrode of the upper modulation arm, configured to receive the first sub optical signal and the first driving signal, and pulse-modulate the first sub optical signal with the first driving signal; a lower arm driving electrode of the lower modulation arm, configured to receive the second sub optical signal and the second driving signal, and perform pulse modulation on the second sub optical signal by using the second driving signal; the output end is used for outputting PAM-4 optical signals which are modulated, coupled and superposed with the first sub optical signals and the second sub optical signals; wherein a rising edge or a falling edge of the second drive signal is synchronized in time with a rising edge or a falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal.
Optionally, the dual-arm driven four-stage pulse amplitude modulator further includes an electrical signal driver and an adjustable electrical signal delay line; the electric signal driver is used for generating the first driving signal and the third driving signal and sending the first driving signal to the upper arm driving electrode; the adjustable electric signal delay line is configured to receive the third driving signal sent by the electric signal driver, perform delay processing on a timing sequence of the third driving signal to obtain the second driving signal, and send the second driving signal to the lower arm driving electrode.
Optionally, the dual-arm driven four-stage pulse amplitude modulator further includes a beam splitter; the beam splitter is configured to split the optical signal into the first sub optical signal and the second sub optical signal.
Optionally, a ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; or the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 1: 4.
The embodiment of the invention provides a two-arm driving four-level pulse amplitude modulator and a modulation method thereof. In this way, even if the amplitude of the first driving signal is equal to the amplitude of the second driving signal, the PAM-4 optical signal that is a coupled superposition of the first optical sub-signal and the second optical sub-signal modulated by the first driving signal and the second driving signal may be output by pulse-modulating the first optical sub-signal by the second driving signal. The spectrum efficiency is improved, high-speed short optical interconnection is realized, an additional electric attenuator is avoided, and the structure of the four-level pulse amplitude modulator driven by two arms is simplified.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a modulation method of a four-level pulse amplitude modulator driven by two arms according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a four-level pulse amplitude modulator driven by two arms according to an embodiment of the present invention;
fig. 3 is an eye diagram of a first sub-optical signal according to an embodiment of the present invention;
FIG. 4 is a diagram of a first driving signal according to an embodiment of the present invention;
fig. 5 is an eye diagram of a second sub-optical signal according to an embodiment of the present invention;
FIG. 6 is a diagram of a second driving signal according to an embodiment of the present invention;
FIG. 7 is an eye diagram of a PAM-4 optical signal provided by an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a four-level pulse amplitude modulator driven by two arms according to an embodiment of the present invention;
fig. 9a is a schematic structural diagram of a four-level pulse amplitude modulator driven by two arms according to an embodiment of the present invention;
fig. 9b is a schematic structural diagram of a four-level pulse amplitude modulator driven by two arms according to an embodiment of the present invention;
fig. 10 is an eye diagram of a PAM-4 optical signal provided by an embodiment of the present invention.
Reference numerals:
11-upper modulation arm; 111-upper arm drive electrode; 112-upper modulation arm doped waveguide; 12-lower modulation arm; 121-lower arm drive electrode; 122-lower modulation arm doped waveguide; 13-an optical coupler; 14-an electrical signal driver; 15-an adjustable electrical signal delay line; 16-beam splitter.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a modulation method of a four-stage pulse amplitude modulator driven by two arms, which can be realized by the following steps as shown in fig. 1:
s11, inputting an optical signal to the input terminal.
As shown in fig. 2, the mach-zehnder intensity modulator includes an input, an upper modulation arm 11, a lower modulation arm 12, and an output.
In some embodiments, as shown in FIG. 9b, upper modulation arm 11 comprises upper arm drive electrode 111 and upper modulation arm doped waveguide 112; the lower modulation arm 12 includes a lower arm drive electrode 121 and a lower modulation arm doped waveguide 122.
In some embodiments, the intensity of the optical signal is not limited to the actual requirement.
In some embodiments, the optical signal may be, for example, a laser.
S12, dividing the optical signal into a first sub optical signal and a second sub optical signal, where the first sub optical signal enters the upper modulation arm 11, the second sub optical signal enters the lower modulation arm 12, and simultaneously, the first driving signal is input to the upper modulation arm 11 and the second driving signal is input to the lower modulation arm 12 synchronously; wherein the intensity of the first sub optical signal is different from the intensity of the second sub optical signal; a rising or falling edge of the second drive signal being synchronized in time with a rising or falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal.
Here, the first sub optical signal actually enters the upper modulation arm doped waveguide 112 of the upper modulation arm 11, and at the same time, the first drive signal is synchronously input to the upper arm drive electrode 111 of the upper modulation arm 11. The modulation of the first sub optical signal may be adjusted by adjusting the magnitude of the first drive signal.
The second sub-optical signal actually enters the lower modulation arm doped waveguide 122 of the lower modulation arm 12, while the second drive signal is synchronously input to the lower arm drive electrode 121 of the lower modulation arm 12. The modulation of the second sub optical signal may be adjusted by adjusting the magnitude of the second drive signal.
In some embodiments, the mach-zehnder intensity modulators are placed differently, and the upper modulation arm 11 and the lower modulation arm 12 may be interchanged, which is not particularly limited in the embodiments of the present invention.
In some embodiments, the intensity of the first sub optical signal may be greater than the intensity of the second sub optical signal; alternatively, the intensity of the first sub optical signal may be smaller than the intensity of the second sub optical signal.
Illustratively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1:2 or 2: 1; alternatively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1:4 or 4: 1.
In some embodiments, the rising or falling edge of the second drive signal may be synchronized in time with the rising or falling edge of the first drive signal by adjusting the timing of the first drive signal. Alternatively, the rising edge or the falling edge of the second drive signal may be synchronized in time with the rising edge or the falling edge of the first drive signal by adjusting the timing of the second drive signal. Alternatively, the rising edge or the falling edge of the second drive signal may be synchronized in time with the rising edge or the falling edge of the first drive signal by adjusting the timing of the second drive signal and the second drive signal.
In some embodiments, the rising or falling edge of the second drive signal, synchronized in time with the rising or falling edge of the first drive signal, comprises:
the rising edge of the second drive signal is synchronized in time with the rising edge of the first drive signal. Alternatively, the rising edge of the second drive signal is synchronized in time with the falling edge of the first drive signal. Alternatively, the falling edge of the second drive signal is synchronized in time with the falling edge of the first drive signal. Alternatively, the falling edge of the second drive signal is synchronized in time with the rising edge of the first drive signal.
And S13, performing pulse modulation on the first sub optical signal by using the first driving signal, performing pulse modulation on the second sub optical signal by using the second driving signal, and outputting a PAM-4 optical signal which is obtained by modulating the first sub optical signal and the second sub optical signal and is coupled and superposed from an output end.
Here, the PAM-4 optical signal may be output by coupling using the optical coupler 13.
Taking the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal as 2:1, the eye diagram of the first sub optical signal as shown in fig. 3, the sequence of the first drive signal as 1101100 (fig. 4), the eye diagram of the second sub optical signal as shown in fig. 5, and the sequence of the second drive signal as 1010110 (fig. 6) as examples, under the condition that the amplitudes of the first drive signal and the second drive signal are the same, the amplitude of the first sub optical signal after pulse modulation by the first drive signal is twice as large as the amplitude of the second sub optical signal after pulse modulation by the second drive signal, the sequence of the PAM-4 optical signal output from the output end is 3212310, and the eye diagram of the PAM-4 optical signal output from the output end is shown in fig. 7.
It can be seen that the PAM-4 optical signal output by the output terminal is: and the first sub optical signal is subjected to pulse modulation by the first driving signal, and is linearly superposed with the second sub optical signal after being subjected to pulse modulation by the second driving signal.
In the related art, the upper modulation arm 11 and the lower modulation arm 12 of the mach-zehnder intensity modulator may be used simultaneously to improve spectral efficiency. However, the amplitude of the first driving signal is half of the amplitude of the second driving signal, and this method needs to attenuate the first driving signal to half of the amplitude of the second driving signal, so that an additional attenuator is needed, and the complexity of the two-arm driving four-stage pulse amplitude modulator is increased.
Based on this, the embodiment of the present invention provides a modulation method for a dual-arm driven four-level pulse amplitude modulator, which uses the existing structure of the dual-arm driven four-level pulse amplitude modulator to input a first sub-optical signal to the upper-arm driving electrode 111 and a second sub-optical signal to the lower-arm driving electrode 121, respectively, and the intensity of the first sub-optical signal is different from the intensity of the second sub-optical signal. In this way, even if the amplitude of the first driving signal is equal to the amplitude of the second driving signal, the PAM-4 optical signal that is a coupled superposition of the first optical sub-signal and the second optical sub-signal modulated by the first driving signal and the second driving signal may be output by pulse-modulating the first optical sub-signal by the second driving signal. The spectrum efficiency is improved, high-speed short optical interconnection is realized, an additional electric attenuator is avoided, and the structure of the four-level pulse amplitude modulator driven by two arms is simplified.
Optionally, as shown in fig. 8, before inputting the optical signal to the input end, the modulation method in which the four-stage pulse amplitude modulator is driven by two arms further includes: the electric signal driver 14 generates a first drive signal and a third drive signal, and transmits the first drive signal to the upper arm drive electrode 111 and the third drive signal to the lower arm drive electrode 121.
The modulation method of the two-arm driven four-stage pulse amplitude modulator after the electric signal driver 14 generates the first drive signal and the third drive signal and before the first drive signal is synchronously input to the upper arm drive electrode 111 and the second drive signal is synchronously input to the lower arm drive electrode 121, further comprises: the electrical signal driver 14 sends a third drive signal to the adjustable electrical signal delay line 15; the adjustable electric signal delay line 15 receives the third driving signal, and performs delay processing on the time sequence of the third driving signal to obtain a second driving signal; the adjustable electrical signal delay line 15 transmits the second drive signal to the lower arm drive electrode 121.
In some embodiments, the amplitude of the third driving signal is the same as the amplitude of the second driving signal, since the adjustable electrical signal delay line 15 only performs timing delay processing on the third driving signal.
In the embodiment of the present invention, the electrical signal driver 14 may be used to generate the first driving signal and the third driving signal, wherein the electrical signal driver 14 may directly send the first driving signal to the upper arm driving electrode 111; the electric signal driver 14 first sends the third driving signal to the adjustable electric signal delay line 15, performs timing delay processing on the third driving signal by using the adjustable electric signal delay line 15 to obtain a second driving signal, and then the adjustable electric signal delay line 15 sends the second driving signal to the lower arm driving electrode 121. In this way, it is ensured that the rising or falling edge of the second drive signal is synchronized in time with the rising or falling edge of the first drive signal.
Optionally, as shown in fig. 9a and 9b, the splitting the optical signal into a first sub optical signal and a second sub optical signal includes: the optical signal is split into a first sub optical signal and a second sub optical signal by means of a beam splitter 16.
Optionally, a ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; alternatively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1: 4.
Taking the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal as 4:1, the arm lengths of the upper arm driving electrode 111 and the lower arm driving electrode 121 as 2000um, and the peak values of the amplitudes of the first driving signal and the second driving signal as 1V as an example, an eye diagram of the PAM-4 optical signal output by the output terminal converted into an electrical signal by the standard detector is shown in fig. 10. It can be seen that the PAM-4 optical signal output from the upper modulation arm 11 just overlaps the PAM-4 optical signal output from the lower modulation arm 12 at each stage, and therefore, it is preferable that the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; alternatively, the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is preferably 1: 4.
An embodiment of the present invention further provides a four-stage pulse amplitude modulator driven by two arms, as shown in fig. 2, where the mach-zehnder intensity modulator includes an input end, an upper modulation arm 11, a lower modulation arm 12, and an output end.
An input terminal for receiving an optical signal and transmitting the optical signal to the upper arm driving electrode 111 and the lower arm driving electrode 121; the optical signal includes a first sub optical signal and a second sub optical signal, and the intensity of the first sub optical signal is different from the intensity of the second sub optical signal.
The upper arm driving electrode 111 of the upper modulation arm 11 is configured to receive the first sub optical signal and the first driving signal, and pulse-modulate the first sub optical signal with the first driving signal.
The lower arm driving electrode 121 of the lower modulation arm 12 is configured to receive the second sub optical signal and the second driving signal, and pulse-modulate the second sub optical signal with the second driving signal.
And the output end is used for outputting the PAM-4 optical signal which is obtained by modulating the first sub optical signal and the second sub optical signal and then coupling and superposing the first sub optical signal and the second sub optical signal.
Wherein a rising edge or a falling edge of the second drive signal is synchronized in time with a rising edge or a falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal.
In some embodiments, as shown in FIG. 9b, upper modulation arm 11 comprises upper arm drive electrode 111 and upper modulation arm doped waveguide 112; the lower modulation arm 12 includes a lower arm drive electrode 121 and a lower modulation arm doped waveguide 122.
In some embodiments, the intensity of the optical signal is not limited to the actual requirement.
In some embodiments, the optical signal may be, for example, a laser.
In some embodiments, the mach-zehnder intensity modulators are placed differently, and the upper modulation arm 11 and the lower modulation arm 12 may be interchanged, which is not particularly limited in the embodiments of the present invention.
In some embodiments, the intensity of the first sub optical signal may be greater than the intensity of the second sub optical signal; alternatively, the intensity of the first sub optical signal may be smaller than the intensity of the second sub optical signal.
Illustratively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1:2 or 2: 1; alternatively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1:4 or 4: 1.
In some embodiments, the rising or falling edge of the second drive signal may be synchronized in time with the rising or falling edge of the first drive signal by adjusting the timing of the first drive signal. Alternatively, the rising edge or the falling edge of the second drive signal may be synchronized in time with the rising edge or the falling edge of the first drive signal by adjusting the timing of the second drive signal. Alternatively, the rising edge or the falling edge of the second drive signal may be synchronized in time with the rising edge or the falling edge of the first drive signal by adjusting the timing of the second drive signal and the second drive signal.
In some embodiments, the rising or falling edge of the second drive signal, synchronized in time with the rising or falling edge of the first drive signal, comprises:
the rising edge of the second drive signal is synchronized in time with the rising edge of the first drive signal. Alternatively, the rising edge of the second drive signal is synchronized in time with the falling edge of the first drive signal. Alternatively, the falling edge of the second drive signal is synchronized in time with the falling edge of the first drive signal. Alternatively, the falling edge of the second drive signal is synchronized in time with the rising edge of the first drive signal.
Taking the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal as 2:1, the eye diagram of the first sub optical signal as shown in fig. 3, the sequence of the first drive signal as 1101100 (fig. 4), the eye diagram of the second sub optical signal as shown in fig. 5, and the sequence of the second drive signal as 1010110 (fig. 6) as examples, under the condition that the amplitudes of the first drive signal and the second drive signal are the same, the amplitude of the first sub optical signal after pulse modulation by the first drive signal is twice as large as the amplitude of the second sub optical signal after pulse modulation by the second drive signal, the sequence of the PAM-4 optical signal output from the output end is 3212310, and the eye diagram of the PAM-4 optical signal output from the output end is shown in fig. 7.
It can be seen that the PAM-4 optical signal output by the output terminal is: and the first sub optical signal is subjected to pulse modulation by the first driving signal, and is linearly superposed with the second sub optical signal after being subjected to pulse modulation by the second driving signal.
In the related art, the upper modulation arm 11 and the lower modulation arm 12 of the mach-zehnder intensity modulator may be used simultaneously to improve spectral efficiency. However, the amplitude of the first driving signal is half of the amplitude of the second driving signal, and this method needs to attenuate the first driving signal to half of the amplitude of the second driving signal, so that an additional attenuator is needed, and the complexity of the two-arm driving four-stage pulse amplitude modulator is increased.
Based on this, the embodiment of the present invention provides a dual-arm driving four-level pulse amplitude modulator, which uses the existing structure of the dual-arm driving four-level pulse amplitude modulator to input a first sub-optical signal to the upper-arm driving electrode 111 and a second sub-optical signal to the lower-arm driving electrode 121, and the intensity of the first sub-optical signal is different from the intensity of the second sub-optical signal. In this way, even if the amplitude of the first driving signal is equal to the amplitude of the second driving signal, the first sub optical signal may be pulse-modulated by the first driving signal and the second sub optical signal may be pulse-modulated by the second driving signal, so as to output a linearly superimposed PAM-4 optical signal that is a coupled superposition of the first sub optical signal and the second sub optical signal after modulation. The spectrum efficiency is improved, high-speed short optical interconnection is realized, an additional electric attenuator is avoided, and the structure of the four-level pulse amplitude modulator driven by two arms is simplified.
Optionally, as shown in fig. 8, the two-arm driving four-stage pulse amplitude modulator further includes an electric signal driver 14; and an electric signal driver 14 for generating the first drive signal and the third drive signal, and transmitting the first drive signal to the upper arm drive electrode 111 and the third drive signal to the lower arm drive electrode 121.
The double-arm driving four-stage pulse amplitude modulator also comprises an adjustable electric signal delay line 15; and an adjustable electrical signal delay line 15, configured to receive the third driving signal sent by the electrical signal driver 14, perform delay processing on a timing sequence of the third driving signal to obtain a second driving signal, and send the second driving signal to the lower arm driving electrode 121.
In some embodiments, the amplitude of the third driving signal is the same as the amplitude of the second driving signal, since the adjustable electrical signal delay line 15 only performs timing delay processing on the third driving signal.
In the embodiment of the present invention, the electrical signal driver 14 may be used to generate the first driving signal and the third driving signal, wherein the electrical signal driver 14 may directly send the first driving signal to the upper arm driving electrode 111; the electric signal driver 14 first sends the third driving signal to the adjustable electric signal delay line 15, performs timing delay processing on the third driving signal by using the adjustable electric signal delay line 15 to obtain a second driving signal, and then the adjustable electric signal delay line 15 sends the second driving signal to the lower arm driving electrode 121. In this way, it is ensured that the rising or falling edge of the second drive signal is synchronized in time with the rising or falling edge of the first drive signal.
Optionally, as shown in fig. 9a and 9b, the two-arm driven four-stage pulse amplitude modulator further includes a beam splitter 16; a beam splitter 16 for splitting the optical signal into a first sub optical signal and a second sub optical signal.
Optionally, a ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; alternatively, the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 1: 4. Taking the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal as 4:1, the arm lengths of the upper arm driving electrode 111 and the lower arm driving electrode 121 as 2000um, and the peak values of the amplitudes of the first driving signal and the second driving signal as 1V as an example, an eye diagram of the PAM-4 optical signal output by the output terminal converted into an electrical signal by the standard detector is shown in fig. 10. It can be seen that the PAM-4 optical signal output from the upper modulation arm 11 just overlaps the PAM-4 optical signal output from the lower modulation arm 12 at each stage, and therefore, it is preferable that the ratio of the intensity of the first sub optical signal to the intensity of the second sub optical signal is 4: 1; alternatively, the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is preferably 1: 4.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (8)
1. A modulation method of a four-level pulse amplitude modulator driven by two arms is characterized by comprising the following steps:
inputting an optical signal to an input terminal;
dividing the optical signal into a first sub optical signal and a second sub optical signal, wherein the first sub optical signal enters an upper modulation arm, the second sub optical signal enters a lower modulation arm, and a first driving signal is synchronously input to an upper arm driving electrode of the upper modulation arm and a second driving signal is synchronously input to a lower arm driving electrode of the lower modulation arm; wherein the intensity of the first sub optical signal is different from the intensity of the second sub optical signal; a rising or falling edge of the second drive signal is synchronized in time with a rising or falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal;
and performing pulse modulation on the first sub optical signal by using the first driving signal, performing pulse modulation on the second sub optical signal by using the second driving signal, and outputting a PAM-4 optical signal which is obtained by modulating the first sub optical signal and the second sub optical signal and is coupled and superposed from an output end.
2. The modulation method of a double-arm driven four-stage pulse amplitude modulator according to claim 1, wherein before inputting an optical signal to an input end, the modulation method of a double-arm driven four-stage pulse amplitude modulator further comprises:
the electric signal driver generates the first driving signal and the third driving signal;
the electric signal driver sends the third driving signal to an adjustable electric signal delay line;
the adjustable electric signal delay line receives the third driving signal, and performs delay processing on the time sequence of the third driving signal to obtain a second driving signal;
the adjustable electrical signal delay line sends the second drive signal to the lower arm drive electrode while an electrical signal driver sends the first drive signal to the upper arm drive electrode.
3. The modulation method of a two-arm driven four-stage pulse amplitude modulator according to claim 1, wherein the dividing the optical signal into a first sub-optical signal and a second sub-optical signal comprises:
splitting the optical signal into the first sub optical signal and the second sub optical signal with a beam splitter.
4. A modulation method of a two-arm driven four-stage pulse amplitude modulator according to any one of claims 1 to 3, characterized in that the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 4: 1; or the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 1: 4.
5. A four-level pulse amplitude modulator driven by two arms is characterized by comprising a Mach-Zehnder intensity modulator, wherein the Mach-Zehnder intensity modulator comprises an input end, an upper modulation arm, a lower modulation arm and an output end;
the input end is used for receiving an optical signal and sending the optical signal to the upper modulation arm and the lower modulation arm; the optical signal comprises a first sub optical signal and a second sub optical signal, and the intensity of the first sub optical signal is different from the intensity of the second sub optical signal;
an upper arm driving electrode of the upper modulation arm, configured to receive the first sub optical signal and a first driving signal, and pulse-modulate the first sub optical signal with the first driving signal;
the lower arm driving electrode of the lower modulation arm is used for receiving the second sub optical signal and a second driving signal and performing pulse modulation on the second sub optical signal by using the second driving signal;
the output end is used for outputting PAM-4 optical signals which are modulated, coupled and superposed with the first sub optical signals and the second sub optical signals;
wherein a rising edge or a falling edge of the second drive signal is synchronized in time with a rising edge or a falling edge of the first drive signal; the amplitude of the first drive signal is equal to the amplitude of the second drive signal.
6. The dual-arm driven four-level pulse amplitude modulator of claim 5, further comprising an electrical signal driver and an adjustable electrical signal delay line;
the electric signal driver is used for generating the first driving signal and the third driving signal and sending the first driving signal to the upper arm driving electrode;
the adjustable electric signal delay line is configured to receive the third driving signal sent by the electric signal driver, perform delay processing on a timing sequence of the third driving signal to obtain the second driving signal, and send the second driving signal to the lower arm driving electrode.
7. The dual-arm driven four-level pulse amplitude modulator of claim 5, further comprising a beam splitter;
the beam splitter is configured to split the optical signal into the first sub optical signal and the second sub optical signal.
8. A dual-arm driven four-level pulse amplitude modulator according to any of claims 5-7, wherein the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 4: 1; or the ratio of the intensity of the first sub-optical signal to the intensity of the second sub-optical signal is 1: 4.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104506241A (en) * | 2014-12-26 | 2015-04-08 | 武汉邮电科学研究院 | Two-arm drive four-stage pulse amplitude modulator and method |
| CN106501971A (en) * | 2016-12-20 | 2017-03-15 | 武汉邮电科学研究院 | Differential driving Mach once moral intensity modulator and method |
| CN108616310A (en) * | 2018-04-27 | 2018-10-02 | 中国科学院半导体研究所 | Increase the method that Dare modulator carries out level Four pulse amplitude modulation based on Mach |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104506241A (en) * | 2014-12-26 | 2015-04-08 | 武汉邮电科学研究院 | Two-arm drive four-stage pulse amplitude modulator and method |
| CN106501971A (en) * | 2016-12-20 | 2017-03-15 | 武汉邮电科学研究院 | Differential driving Mach once moral intensity modulator and method |
| CN108616310A (en) * | 2018-04-27 | 2018-10-02 | 中国科学院半导体研究所 | Increase the method that Dare modulator carries out level Four pulse amplitude modulation based on Mach |
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