CN115882955B - Low-spurious light modulator bias control device and method - Google Patents
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Abstract
The invention discloses a low-spurious-emission optical modulator bias control device and a method, wherein the device comprises a laser, an optical modulator, an optical coupler and a bias control circuit, the bias control circuit comprises an optical detector, a balun and a differential detection module, the input end of the optical modulator is connected with the output end of the laser, the output end of the optical modulator is connected with the input end of the optical coupler, the first output end of the optical coupler is connected with the input end of the optical detector, the output end of the optical detector is connected with the input end of the balun, the two output ends of the balun are respectively connected with the two input ends of the differential detection module, and the output end of the differential detection module is connected with the bias control signal input end of the optical modulator; the balun is used for converting an input signal into two paths of output signals; the differential detection module performs subtraction processing on two paths of signals output by the balun; the invention has the advantages that: the spurious interference caused by the pilot is solved, thereby enabling the optical modulator to operate stably.
Description
Technical Field
The invention relates to the technical field of microwave photon and optical communication, in particular to a low-stray light modulator bias control device and method.
Background
The optical modulator has the advantages of large modulation bandwidth, high modulation efficiency, small frequency chirp and the like, and is widely applied to optical fiber transmission systems such as optical fiber communication, optical carrier radio frequency (ROF), optical fiber cable televisions and the like. The modulation characteristic of the optical modulator is nonlinear, and the optical modulator is loaded with different bias voltages, so that the modulation working modes of different working points (comprising a maximum point, a linear point and a minimum point) can be realized. However, due to factors such as ambient temperature, vibration, stress variation and the like, the bias operating point of the modulator can shift, so that the quality of a modulated signal is poor or the error rate of a transmission system is increased.
In order to stabilize the operation of the optical modulator, the bias voltage needs to be corrected by using a modulator bias control device. A more stable and reliable bias control method is pilot method [ Feng Zhenhua, "study of arbitrary bias operating point locking technique of LiNbO3 Mach-Zehnder modulator". Optical report.32 (12): 73-78 (2012) ]. The pilot frequency method has the working principle that a low-frequency disturbance signal with specific frequency is superimposed on the DC bias voltage of a modulator, the output end of the modulator is connected with a low-speed optical detector, the amplitudes of fundamental waves and second harmonics of the disturbance signal output by the optical detector are detected, the working point state of the modulator is judged through the amplitude ratio of the fundamental waves to the second harmonics, and the amplitude ratio is used as a feedback parameter to realize the automatic control of the bias voltage.
The pilot method has the advantages of good stability and high control precision, but the pilot method has the defect that disturbance signals can be modulated on useful working signals to become stray interference signals of a system, the working signals can be interfered and degraded, and the stronger the amplitude of the pilot disturbance signals, the larger the influence on the system. Because the laser, the optical fiber and the optical detector of the optical transmission link all generate certain noise, and the pilot frequency bias control device also has circuit noise, the noise forms the noise of the system together. The amplitudes of the fundamental wave and the second harmonic wave of the disturbance signal in the signal detection unit must be higher than the noise of the detection system in order to correctly detect the amplitudes of the fundamental wave and the second harmonic wave. The amplitude of the pilot signal cannot be infinitely small and pilot interference cannot be avoided. In high sensitivity communication and radar systems, the spurs caused by the pilot signal are not negligible and even become a limiting factor for these systems.
In chinese patent application publication No. CN110166141a, a method for correcting pilot frequency to avoid pilot frequency spurious during idle operation is proposed in a device and method for controlling the negotiation of bias voltage of optical modulator. This approach has two limitations. On the one hand, some systems do not have idle time for receiving pilot signals, i.e. the system must be interfered with once loaded with pilot signals; on the other hand, external vibration or disturbance cannot be effectively handled when the bias voltage is kept in the operation mode.
Disclosure of Invention
The invention aims to solve the technical problem that the bias control device of the optical modulator in the prior art cannot solve the problem that the optical modulator cannot work stably due to stray interference caused by pilot frequency.
The invention solves the technical problems by the following technical means: the utility model provides a low spurious light modulator bias control device, including laser instrument (1), light modulator (2), light coupler (3) and bias control circuit (4), bias control circuit (4) are including light detector (40), balun (41), differential detection module (42), the input of light modulator (2) links to each other with the output of laser instrument (1), the output of light modulator (2) links to each other with the input of light coupler (3), the first output of light coupler (3) links to each other with the input of light detector (40), the output of light detector (40) links to each other with the input of balun (41), two outputs of balun (41) link to each other with two inputs of differential detection module (42), the output of differential detection module (42) links to each other with the input of control unit (43), the output of control unit (43) links to each other with the input of bias signal generation unit (44), the output of bias signal generation unit (44) links to the bias control signal input of light modulator (2), output bias control signal; the balun (41) is used for converting an input signal into two paths of output signals, and the two paths of signals are equal in amplitude and opposite in phase; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41).
The beneficial effects are that: the invention converts an input signal into two paths of output signals through the balun (41), wherein the two paths of signals have equal amplitude and opposite phases; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41), and the amplitude of the signals after subtraction operation is doubled due to opposite phases, and common-mode noise superposed on the signals is counteracted, so that the detection signal-to-noise ratio of error signals is improved, stray interference caused by pilot frequency is solved, and the optical modulator works stably.
Further, the differential detection module (42) comprises an operational amplifier (421) and a digital acquisition unit (422), two output ends of the balun (41) are respectively connected with a non-inverting input end and an inverting input end of the operational amplifier (421), and an output end of the operational amplifier (421) is connected with an input end of the digital acquisition unit (422).
Further, the operational amplifier (421) performs analog subtraction on two paths of inverted signals output by the balun (41), the amplitude of the differential output signal is doubled, circuit noise is partially cancelled, and the digital acquisition unit (422) converts the analog signal output by the balun (41) into a digital signal for output.
Further, the differential detection module (42) comprises a first digital collector (423), a second digital collector (424) and a digital differential arithmetic unit (425), two output ends of the balun (41) are respectively connected with input ends of the first digital collector (423) and the second digital collector (424), an output end of the first digital collector (423) is connected with a first input end of the digital differential arithmetic unit (425), and an output end of the second digital collector (424) is connected with a second input end of the digital differential arithmetic unit (425).
Further, the first digital collector (423) and the second digital collector (424) perform analog-to-digital conversion on two paths of opposite signals output by the balun (41), convert the analog signals output by the balun (41) into digital signals, and then perform subtraction calculation, namely digital differential operation, through the digital differential operator (425), the amplitude of the differential output signals is doubled, and circuit noise is partially cancelled.
The invention also provides a method for the bias control device of the low-spurious-emission optical modulator, wherein the output signal of the optical modulator (2) is coupled into an optical detector (40) through an optical coupler (3), the optical detector (40) outputs the signal to a balun (41), and the balun (41) converts the input signal into two paths of output signals, and the two paths of signals have equal amplitude and opposite phase; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41) through differential detection, the amplitude of the signals after subtraction is doubled due to opposite phases, common-mode noise superposed on the signals is counteracted, and then the output signal of the differential detection module (42) generates a bias control signal to modulate the optical modulator.
Further, the radio frequency signal modulated at the signal input end of the optical modulator (2) is V 3cos(2πfx), and the bias control signal output by the differential detection module (42) is V 0+V1cos(2πfd); wherein f d is the pilot frequency, f x is the frequency of the working signal, and f d＜＜fx.
Further, the photodetector (40) output voltage is:
e(t)＝V1cos(2πfdt)+V1Acos[2πfdt]+Vn (1)
Wherein V n is noise voltage, e (t) is an input error signal of a bias control circuit adopted by a traditional non-differential detection device, V 1 and V 1 A are amplitudes of fundamental wave and second harmonic respectively, and V 1 and V 1 A are both larger than V n;
for a non-differential detection device, the voltage at the second output (signal output) of the optocoupler is:
Vout＝V3cos(2πfxt)+V1Bcos[2π(fx+fd)t] (2)
Where signal f x+d is a unwanted spurious interference signal, V 1 B is the amplitude value of signal f x+d, and V 3 is the amplitude value of signal f x.
Further, the voltages at the two output terminals of the balun (41) are respectively:
subtracting operation is carried out through a difference detection module (42), and error signal voltage is obtained as follows:
the actual differential system can not completely eliminate the noise, the noise always has residues, and the residual noise voltage is Is the noise suppression ratio.
Further, after the differential operation is performed by the differential detection module (42), the voltage of the second output terminal of the optocoupler (3) is:
Vout＝V3cos(2πfxt)+(V1B/X)cos[2π(fx+fd)t] (6)
Wherein V 1 B/X is the amplitude value of the signal f x+d, the spurious suppression ratio is XV 3/V1 B, and compared with a non-differential detection device, the spurious suppression ratio of the differential detection module (42) is improved by X times.
The invention has the advantages that:
(1) The invention converts an input signal into two paths of output signals through the balun (41), wherein the two paths of signals have equal amplitude and opposite phases; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41), and the amplitude of the signals after subtraction operation is doubled due to opposite phases, common-mode noise superimposed on the signals is counteracted, the detection signal-to-noise ratio of error signals is improved, stray interference caused by pilot frequency is solved, and the optical modulator works stably.
(2) The invention adopts a differential detection method to reduce common mode noise of the system and improves the detection signal-to-noise ratio of the error signal, thereby adopting a pilot signal with smaller amplitude to complete the bias working point control of the optical modulator. Because the loaded pilot signal amplitude is small, the spurious interference amplitude of the working signal is reduced, and the method can be applied to high-sensitivity communication and large dynamic radar systems. The accuracy of the offset operating point is higher because differential detection results in higher accuracy of the error signal detection.
Drawings
FIG. 1 is a schematic diagram of a low spurious optical modulator bias control device disclosed in embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of a low spurious optical modulator bias control device according to embodiment 2 of the present invention;
fig. 3 is a schematic diagram of a low spurious optical modulator bias control device according to embodiment 3 of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, a low spurious optical modulator bias control device comprises a laser 1, an optical modulator 2, an optical coupler 3 and a bias control circuit 4, wherein the bias control circuit 4 comprises an optical detector 40, a balun 41, a differential detection module 42, a control unit 43 and a bias signal generation unit 44, the input end of the optical modulator 2 is connected with the output end of the laser 1, the output end of the optical modulator 2 is connected with the input end of the optical coupler 3, the first output end of the optical coupler 3 is connected with the input end of the optical detector 40, the output end of the optical detector 40 is connected with the input end of the balun 41, the two output ends of the balun 41 are respectively connected with the two input ends of the differential detection module 42, the output end of the differential detection module 42 is connected with the input end of the control unit 43, the output end of the control unit 43 is connected with the input end of the bias signal generation unit 44, and the output end of the bias signal generation unit 44 is connected with the bias control signal input end of the optical modulator 2 to output bias control signals; the balun 41 is used for converting an input signal into two paths of output signals, and the two paths of signals have equal amplitude and opposite phases; the differential detection module 42 performs subtraction processing on the two signals output by the balun 41.
The optical modulator 2 includes a lithium niobate electro-optical modulator, a lithium niobate thin film electro-optical modulator, an indium phosphide optical modulator, and a silicon optical modulator. The output signal of the optical modulator 2 is coupled into the optical detector 40 through the optical coupler 3, the optical detector 40 converts the optical signal into an electric signal and outputs the electric signal to the balun 41, the balun 41 converts the input signal into two paths of output signals, and the two paths of signals are equal in amplitude and opposite in phase; the differential detection module 42 performs subtraction processing on the two paths of signals output by the balun 41 through differential detection, the amplitude of the signals after subtraction is doubled due to opposite phases, common-mode noise superimposed on the signals is cancelled, and then the output signal of the differential detection module 42 generates a bias control signal to modulate the optical modulator.
Through the technical scheme, the balun 41 converts an input signal into two paths of output signals, wherein the two paths of signals have equal amplitude and opposite phases; the differential detection module 42 performs subtraction processing on the two paths of signals output by the balun 41, and the phase is opposite, so that the amplitude of the signal after subtraction operation is doubled, and the common mode noise superimposed on the signal is counteracted, thereby improving the detection signal-to-noise ratio of the error signal, solving the spurious interference caused by pilot frequency, and enabling the optical modulator to work stably.
Example 2
As shown in fig. 2, embodiment 2 of the present invention differs from embodiment 1 in that: the differential detection module 42 includes an operational amplifier 421 and a digital acquisition unit 422, two output ends of the balun 41 are respectively connected with a non-inverting input end and an inverting input end of the operational amplifier 421, and an output end of the operational amplifier 421 is connected with an input end of the digital acquisition unit 422. The operational amplifier 421 performs an analog subtraction operation on the two inverted signals output by the balun 41, the amplitude of the differential output signal is doubled, the circuit noise is partially cancelled, and the digital acquisition unit 422 converts the analog signal output by the balun 41 into a digital signal for output.
The laser 1 provides an optical source, i.e. an optical carrier, for the whole system. The function of the optical modulator 2 is to perform electro-optical conversion, modulate an electrical signal to be transmitted onto an optical carrier, the "signal input" port of the optical modulator 2 is an input port of the electrical signal, and the optical signal modulated by the electrical signal is output by the optical modulator 2 and then transmitted remotely through an optical medium such as an optical fiber. The "bias control signal" port of the optical modulator 2 is used to load a dc bias signal to ensure that the modulator operates at a set operating point. The optical coupler 3 is used for dividing the input optical signal into two paths, for example, the splitting ratio of the optical coupler is 1:99. The first output terminal of the optocoupler 3 (accounting for 1% of the input optical power of the optocoupler 3) is input to the bias control circuit 4 for implementing an automatic bias control function. The other majority of the power (99% of the input optical power to the optocoupler 3) is used to output a useful modulated optical signal.
The bias control circuit operates as follows: the optical signal output from the first output terminal of the optocoupler 3 is subjected to optical-electrical conversion by the photodetector 40, and an electrical error signal is obtained, and the error signal is converted into a digital error signal after passing through the balun 41, the operational amplifier 421 and the digital acquisition unit 422. The digital error signal is operated on in the control unit 43 on the specific principle that: the amplitude ratio of the fundamental wave f d and the second harmonic wave 2 d has a certain corresponding relation with the bias working point of the modulator, whether the bias working point of the optical modulator 2 is changed can be judged according to the amplitude ratio of the fundamental wave f d and the second harmonic wave 2 d, if the amplitude ratio deviates from the expected value, a control signal (the control signal is calculated by adopting a PID algorithm) is output to the bias signal generating unit 44, and the bias working point of the optical modulator 2 is corrected by changing the bias voltage output by the bias signal generating unit 44.
Assuming that the radio frequency signal modulated at the signal input of the optical modulator 2 is V 3cos(2πfx), the bias control signal output by the bias signal generation 44 is V 0+V1cos(2πfd). Wherein f d is the pilot frequency, f x is the frequency of the working signal, and f d＜＜fx. The first output of the optocoupler 3 is connected to a low-speed photodetector 40 for converting the optical signal into an electrical signal.
Ignoring common divisors and higher order terms that do not affect the result, the photodetector 40 outputs a voltage of:
e(t)＝V1cos(2πfdt)+V1Acos[2πfdt]+Vn (1)
where V n is the noise voltage.
For the existing non-differential bias control device, e (t) is an input error signal of a bias control circuit adopted by other non-differential bias control schemes, and the error signal is digitally acquired to obtain the amplitude ratio of the fundamental wave f d and the second harmonic wave 2f d. Because of the noise voltage, V 1 and V 1 a must be greater than V n for the fundamental and second harmonics to be detected by the digital acquisition unit 422.
Ignoring the common divisor coefficient and higher order terms that do not affect the result, for other non-differential bias control schemes, the second output (signal output) voltage of the optocoupler is:
Vout＝V3cos(2πfxt)+V1Bcos[2π(fx+fd)t] (2)
the signal f x+fd is an unwanted spurious interference signal, and the frequency f x+fd is very close to the frequency f x, so that the spurious interference signal cannot be filtered by the filter. The amplitude ratio V 3/V1 B of signal f x to signal f x+fd is referred to as the spurious suppression ratio, the greater the spurious suppression ratio indicates: the smaller the amplitude of spurious signals f x+fd relative to the amplitude of working signals f x, the less the spurious signals have an effect on the working signals.
For a differential detection system, the voltages at the two outputs of balun 41 are respectively:
The subtraction operation is performed by the operational amplifier 421, and the output voltage of the operational amplifier 421 is obtained as follows:
the actual differential system can not completely eliminate the noise, the noise always has residues, and the residual noise voltage is Is the noise suppression ratio. At this point V 1 and V 1 A are both greater than/>The fundamental and second harmonics may be detected by digital acquisition unit 422.
For the differential detection proposed by the present invention, the amplitude of the pilot signal is reducedThe voltage at the second output (signal output) of the optocoupler becomes:
Vout＝V3cos(2πfxt)+(V1B/X)cos[2π(fx+fd)t] (6)
Wherein, the signal f x+d is a useless spurious interference signal, and V 1 B/X is the amplitude value of the signal f x+d. The spurious suppression ratio is XV 3/V1 B, and compared with a non-differential detection device, the spurious suppression ratio of the differential detection device is improved by X times.
It should be noted that, the formula (2) may be regarded as the output signal voltage of the conventional non-differential scheme. And the formula (6) is the output voltage of the system based on differential detection, the spurious suppression ratio is improved by X times, and the spurious suppression is smaller.
In summary, the voltage at the photodetector output (40) of the present invention is the input "error signal" of the bias control device used in other bias control schemes, and then the present invention adopts a differential detection method to perform differential calculation on the "error signal", which has the following advantages: the detection sensitivity of the error signal is improved, that is, the error signal weaker than the traditional scheme can be detected, f d is the error signal, V 1 is the amplitude of the error signal, the amplitude of f d is reduced by X times and is reduced to V 1/X, and the error signal can still be detected.
Example 3
As shown in fig. 3, embodiment 3 of the present invention is different from embodiment 2 in the specific structure of the differential detection module 42, where the differential detection module 42 includes a first digital collector 423, a second digital collector 424 and a digital differential arithmetic unit 425, two output ends of the balun 41 are respectively connected to the input ends of the first digital collector 423 and the second digital collector 424, the output end of the first digital collector 423 is connected to the first input end of the digital differential arithmetic unit 425, and the output end of the second digital collector 424 is connected to the second input end of the digital differential arithmetic unit 425. The first digital collector 423 and the second digital collector 424 perform analog-to-digital conversion on two paths of inverted signals output by the balun 41, convert the analog signals output by the balun 41 into digital signals, and then perform subtraction, that is, digital differential operation, by the digital differential operator 425, the amplitude of the differential output signals is doubled, and circuit noise is partially cancelled. Therefore, the digital differential detection also improves the detection signal-to-noise ratio of the error signal, thereby adopting the pilot signal with smaller amplitude to complete the bias working point control of the optical modulator and reducing the spurious interference amplitude of the working signal.
In summary, the bias control device based on the pilot method in the prior art has the characteristics of no influence of external temperature and strong anti-interference capability, but pilot signals can be aliased on working signals to generate unnecessary spurious signals. The optical modulator bias control device and method in embodiments 2 and 3 improve the detection signal-to-noise ratio of the error signal by using the differential detection method, so that the amplitude of the input pilot signal can be reduced, thereby reducing the spurious signal intensity on the working signal. The bias control device of the optical modulator can be applied to optical fiber communication, laser communication and optical carrier radio frequency systems.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The low-spurious-emission optical modulator bias control device is characterized by comprising a laser (1), an optical modulator (2), an optical coupler (3) and a bias control circuit (4), wherein the bias control circuit (4) comprises an optical detector (40), a balun (41) and a differential detection module (42), the input end of the optical modulator (2) is connected with the output end of the laser (1), the output end of the optical modulator (2) is connected with the input end of the optical coupler (3), the first output end of the optical coupler (3) is connected with the input end of the optical detector (40), the output end of the optical detector (40) is connected with the input end of the balun (41), the two output ends of the balun (41) are respectively connected with the two input ends of the differential detection module (42), the input end of the differential detection module (42) is connected with the input end of the control unit (43), the output end of the control unit (43) is connected with the input end of the bias signal generation unit (44), and the output end of the bias signal generation unit (44) is connected with the bias control signal input end of the optical modulator (2) to output bias control signals. The balun (41) is used for converting an input signal into two paths of output signals, and the two paths of signals are equal in amplitude and opposite in phase; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41).
2. The low spurious optical modulator bias control device according to claim 1, wherein the differential detection module (42) comprises an operational amplifier (421) and a digital acquisition unit (422), the two output terminals of the balun (41) are respectively connected with the non-inverting input terminal and the inverting input terminal of the operational amplifier (421), and the output terminal of the operational amplifier (421) is connected with the input terminal of the digital acquisition unit (422).
3. A low spurious optical modulator bias control device according to claim 2, wherein said operational amplifier (421) performs an analog subtraction operation on two inverted signals outputted from the balun (41), the amplitude of the differential output signal is doubled, and the circuit noise is partially canceled, and the digital acquisition unit (422) converts the analog signal outputted from the balun (41) into a digital signal for output.
4. The low spurious light modulator bias control device of claim 1, wherein the differential detection module (42) comprises a first digital collector (423), a second digital collector (424) and a digital differential operator (425), wherein two output terminals of the balun (41) are respectively connected with input terminals of the first digital collector (423) and the second digital collector (424), an output terminal of the first digital collector (423) is connected with a first input terminal of the digital differential operator (425), and an output terminal of the second digital collector (424) is connected with a second input terminal of the digital differential operator (425).
5. The low spurious optical modulator bias control device according to claim 4, wherein said first digital collector (423) and said second digital collector (424) analog-to-digital convert two-way inverted signals outputted from the balun (41), convert analog signals outputted from the balun (41) into digital signals, and then perform subtraction, i.e., digital differential operation, by means of a digital differential operator (425), the amplitude of the differential output signal is doubled, and circuit noise is partially canceled.
6. A method of a low spurious optical modulator bias control device according to any of the claims 1-5, characterized in that the output signal of said optical modulator (2) is coupled via an optical coupler (3) into an optical detector (40), the optical detector (40) outputs a signal to a balun (41), the balun (41) converts the input signal into two output signals, the two signals being equal in amplitude and opposite in phase; the differential detection module (42) performs subtraction processing on two paths of signals output by the balun (41) through differential detection, the amplitude of the signals after subtraction is doubled due to opposite phases, common-mode noise superposed on the signals is counteracted, and then the output signal of the differential detection module (42) generates a bias control signal to modulate the optical modulator.
7. The method of a low spurious optical modulator bias control device according to claim 6, wherein the radio frequency signal modulated at the signal input end of the optical modulator (2) is V 3cos(2πfx), and the bias control signal outputted by the differential detection module (42) is V 0+V1cos(2πfd); wherein f d is the pilot frequency, f x is the frequency of the working signal, and f d＜＜fx.
8. A method of a low spurious optical modulator bias control device according to claim 7, wherein said optical detector (40) output voltage is:
e(t)＝V1cos(2πfdt)+V1Acos[2πfdt]+Vn (1)
Wherein V n is noise voltage, e (t) is an input error signal of a bias control circuit adopted by a traditional non-differential detection device, V 1 and V 1 A are amplitudes of fundamental wave and second harmonic respectively, and V 1 and V 1 A are both larger than V n;
For a non-differential detection device, the second output voltage of the optocoupler is:
Vout＝V3cos(2πfxt)+V1Bcos[2π(fx+fd)t] (2)
Where signal f x+fd is a unwanted spurious interference signal, V 1 B is the amplitude value of signal f x+fd, and V 3 is the amplitude value of signal f x.
9. A method of a low spurious optical modulator bias control device according to claim 8, wherein the voltages at the two outputs of said balun (41) are respectively:
subtracting operation is carried out by a difference detection module (42), and the error signal voltage is as follows:
the actual differential system can not completely eliminate the noise, the noise always has residues, and the residual noise voltage is X＞1，/>Is the noise suppression ratio.
10. The method of a low spurious optical modulator bias control device according to claim 9, wherein after differential operation by the differential detection module (42), the second output terminal voltage of the optical coupler (3) is:
Vout＝V3cos(2πfxt)+(V1B/X)cos[2π(fx+fd)t] (6)
Wherein V 1 B/X is the amplitude value of the signal f x+fd, the spurious suppression ratio is XV 3/V1 B, and compared with a non-differential detection device, the spurious suppression ratio of the differential detection module (42) is improved by X times.
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| CN202211580022.0A CN115882955B (en) | 2022-12-09 | 2022-12-09 | Low-spurious light modulator bias control device and method |
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| CN106506092A (en) * | 2016-12-22 | 2017-03-15 | 中国计量大学 | A kind of low noise radio-frequency light transmission module of wide temperature range work |
| CN109104245A (en) * | 2018-09-17 | 2018-12-28 | 中国电子科技集团公司第三十八研究所 | Transmission system when multichannel is steady without the non-co-operation signal of spuious broadband |
| CN114002864A (en) * | 2021-10-27 | 2022-02-01 | 合肥正阳光电科技有限责任公司 | Electro-optical modulator driving device for suppressing pilot frequency stray |
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| CN106506092A (en) * | 2016-12-22 | 2017-03-15 | 中国计量大学 | A kind of low noise radio-frequency light transmission module of wide temperature range work |
| CN109104245A (en) * | 2018-09-17 | 2018-12-28 | 中国电子科技集团公司第三十八研究所 | Transmission system when multichannel is steady without the non-co-operation signal of spuious broadband |
| CN114002864A (en) * | 2021-10-27 | 2022-02-01 | 合肥正阳光电科技有限责任公司 | Electro-optical modulator driving device for suppressing pilot frequency stray |
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| 基于光调制器的宽带低杂散微波光子变频技术研究;郑月;《硕士电子期刊》;20180515;第2018年卷(第5期);全文 * |
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