CN110596918A - Method and device for controlling bias operating point of modulator - Google Patents
Method and device for controlling bias operating point of modulator Download PDFInfo
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Abstract
The embodiment of the application discloses a method for controlling a bias operating point of a modulator, which comprises the following steps: determining a perturbation signal to be applied to a phase modulation electrode of the modulator according to inherent characteristics of the modulator; wherein the disturbance signal is a voltage signal with a specific time-varying periodicity; detecting a signal component having the same frequency as the disturbance signal from an output signal at an output terminal of the modulator; adjusting the initial bias voltage to determine a bias operating point of the modulator based on the magnitude of the signal component. The embodiment of the application also provides a device for controlling the bias operating point of the modulator.
Description
Technical Field
The present application belongs to the field of optical fiber communication technologies, and in particular, to a method and an apparatus for controlling a bias operating point of a modulator.
Background
The requirements of modern communication on the transmission capacity, speed and performance are greatly improved, and coherent optical communication is made out of the great significance of having higher frequency spectrum utilization rate, and becomes an important research direction of modern optical communication research. The modulator is a key device for realizing a high-order modulation code type, and is easily influenced by environmental factors such as temperature, pressure and the like in actual use, so that a static working point of the modulator is easy to drift, the quality and stability of an optical modulation signal are influenced, and the error code performance of a transmission system is deteriorated.
Most of the existing research is directed at the bias voltage control of a lithium niobate (LiNbO3) modulator, and a common method is to introduce a sinusoidal disturbance signal on a phase modulation electrode and detect a first harmonic signal of the sinusoidal disturbance signal to achieve the purposes of detecting and controlling the drift of a working point. And LiNbO3The modulators are based on the linear electro-optic effect, i.e. the optical phase varies linearly with the amplitude of the applied electric field, whereas the modulation characteristics of silicon-based modulators are comparable to LiNbO3The complete difference of the modulators is that the phase change generated by the bias operating point of the silicon-based modulator is based on the thermo-optic effect of silicon and the nonlinear electro-optic effect, namely, the phase change of the modulator is proportional to the square of the bias voltage. In the silicon-based optical modulator, when a conventional sine perturbation signal is used, the locking of a close point (Null point) and an orthogonal point (Quad point) cannot be performed according to the first harmonic of the signal. Therefore, the bias voltage locking method based on the traditional LiNbO3 modulator cannot be directly applied to the silicon-based optical modulator.
Disclosure of Invention
In view of the above, embodiments of the present application provide a method and an apparatus for controlling a bias operating point of a modulator to solve at least one problem in the related art.
The technical scheme of the embodiment of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a method for controlling a bias operating point of a modulator, where the method includes:
determining a perturbation signal to be applied to a phase modulation electrode of the modulator according to inherent characteristics of the modulator; wherein the disturbance signal is a time-varying periodic voltage signal;
detecting a signal component having the same frequency as the disturbance signal from an output signal at an output terminal of the modulator;
adjusting a bias voltage of the phase modulating electrode based on the amplitude of the signal component to determine a biased operating point of the modulator.
In a second aspect, an embodiment of the present application provides an apparatus for controlling a bias operating point of a modulator, where the apparatus includes: a first determination module, a detection module, and a second determination module, wherein:
the first determining module is used for determining the amplitude of a disturbance signal to be applied to a phase modulation electrode of the modulator according to the initial bias voltage of the phase modulation electrode;
the detection module detects a signal component with the same frequency as the disturbance signal from an output signal of the output end of the modulator;
and the second determining module is used for adjusting the bias voltage of the phase modulation electrode according to the amplitude of the signal component so as to determine the bias operating point of the modulator.
The embodiment of the application provides a method and a device for controlling a bias operating point of a modulator. Firstly, determining a disturbing signal to be applied to the phase modulation electrode according to the inherent characteristics of the modulator; then, detecting a signal component having the same frequency as the disturbance signal from an output signal of an output terminal of the modulator; finally, according to the amplitude of the signal component, adjusting the bias voltage of the phase modulation electrode to determine the bias working point of the modulator; therefore, the disturbance signal related to the bias voltage is applied to the phase modulation electrode of the silicon-based optical modulator, and the amplitude of the signal component with the same frequency as the applied disturbance signal is detected in the output signal of the modulator, so that the simple and rapid locking and maintaining of the bias working point of the silicon-based optical modulator can be realized, the control difficulty is reduced, and the control precision is improved.
Drawings
Fig. 1 is a schematic flow chart illustrating an implementation of a method for controlling a bias operating point of a modulator according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of another implementation of a method for controlling a bias operating point of a modulator according to an embodiment of the present application;
FIG. 3 is a schematic flow chart of another implementation of a method for controlling a bias operating point of a modulator according to an embodiment of the present application;
FIG. 4 is a signal transmission characteristic curve of an MZ modulator according to an embodiment of the present application;
FIG. 5 shows an FFT simulation result of Null point in the embodiment of the present application;
FIG. 6 is a FFT simulation result of the Quad point according to the embodiment of the present application;
FIG. 7 is a functional block diagram of a method for controlling the bias operating point of a modulator according to an embodiment of the present application;
FIG. 8 is a schematic diagram of a method for controlling a bias operating point of a modulator according to an embodiment of the present application
FIG. 9 is a schematic flow chart of another implementation of a method for controlling a bias operating point of a modulator according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a control device for controlling the bias operating point of a modulator according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
Example one
An embodiment of the present application provides a method for controlling a bias operating point of a modulator, and fig. 1 is a schematic flow chart illustrating an implementation of the method for controlling the bias operating point of the modulator according to the embodiment of the present application, as shown in fig. 1, the method includes the following steps:
step S101, determining a perturbation signal to be applied to a phase modulation electrode of the modulator according to the inherent characteristics of the modulator.
Here, the modulator may be various modulators, and in one embodiment, may be a Mach-Zehnder (MZ) modulator, or an in-phase-Quadrature (IQ) modulator composed of a plurality of MZ modulators. The modulator is made of silicon light, and is hereinafter referred to as a silicon-based light modulator.
Here, the intrinsic characteristic of the modulator means that the phase modulation principle of the silicon-based optical modulator is realized by thermal modulation, and the phase change of the silicon-based optical modulator is proportional to the square of the bias voltage.
Here, the perturbation signal is a time-varying periodic voltage signal, the perturbation signal applied to the phase modulation electrode is a small-amplitude low-frequency perturbation signal, the frequency of the perturbation signal is selected to be smaller than the 3dB cut-off frequency of the thermo-optic phase shifter of the modulator, and the perturbation amplitude is about 10% of the half-wave voltage of the thermo-optic phase shifter. In order not to affect the correct demodulation of the modulated information, the amplitude of the perturbation signal applied to the phase modulating electrodes of the modulator is much smaller than the amplitude of the modulated signal.
Step S102, detecting a signal component having the same frequency as the disturbance signal from the output signal of the output terminal of the modulator.
Here, the output end of the modulator outputs a modulated optical signal, which needs to be converted into an electrical signal through photoelectric conversion processing, and this step can be realized by a Monitoring Photodiode (MPD) built in the modulator.
Here, since the output optical power has a jitter in the form of a sinusoidal signal due to the added disturbing signal, and the frequency of the sinusoidal signal is the same as the frequency of the added disturbing signal, a signal component having the same frequency as the disturbing signal can be detected by a filter or a data processing unit.
Step S103, adjusting the bias voltage of the phase modulation electrode according to the amplitude of the signal component to determine the bias working point of the modulator.
Here, a signal component having the same frequency as the disturbance signal is detected, and the amplitude of the signal component is further extracted.
Here, the bias operating point of the modulator refers to a special operating point on the transmission curve of the MZ modulator, such as Null point and Quad point, and in practical use, the modulator needs to be biased at a proper operating point.
It should be noted that although the amplitude of the disturbing signal is small, it still has an influence on the light. The optical power amplitude effect caused by the disturbing signal is different at different bias operating points. Whether the bias voltage drifts can be judged by detecting the amplitude of the disturbance signal output by the modulator, and the bias voltage of the phase modulation electrode can be accurately controlled to be stabilized at the optimal working point.
According to the control method of the bias working point of the modulator, firstly, a disturbing signal to be applied to the phase modulation electrode is determined according to the inherent characteristics of the modulator; then, detecting a signal component having the same frequency as the disturbance signal from an output signal of an output terminal of the modulator; finally, according to the amplitude of the signal component, adjusting the bias voltage of the phase modulation electrode to determine the bias working point of the modulator; therefore, the amplitude of a signal component in output light of the modulator, which has the same frequency as the applied disturbance signal, is detected in real time by applying the disturbance signal related to the bias voltage to a phase modulation electrode of the modulator, and the bias working point is locked accordingly, so that the bias working point of the silicon optical modulator can be simply and quickly locked and maintained, the control difficulty is reduced, and the control precision is improved.
Example two
An embodiment of the present application provides a method for controlling a bias operating point of a modulator, and fig. 2 is a schematic flow chart of another implementation of the method for controlling the bias operating point of the modulator in the embodiment of the present application, as shown in fig. 2, the method includes the following steps:
step S201, determining a perturbation signal to be applied to a phase modulation electrode of the modulator according to the inherent characteristic of the modulator.
Step S202, detecting a signal component having the same frequency as the disturbance signal from the output signal of the output terminal of the modulator.
Step S203, performing feedback adjustment on the bias voltage of the phase modulation electrode according to the amplitude of the signal component, so that the amplitude of the signal component is smaller than a first threshold.
Here, the first threshold is set to a minimum value on a transmission curve of the MZ modulator, and the initial bias voltage of the phase modulation electrode is feedback-adjusted by detecting in real time the magnitude of the amplitude of a signal component of the output optical signal having the same frequency as the disturbance signal until the amplitude of the signal component is minimum.
Step S204, determining the bias voltage corresponding to the extracted disturbance signal when the amplitude is smaller than a first threshold value as the bias working point of the phase modulation electrode.
Here, the bias voltage at which the amplitude of the disturbance signal obtained in step S203 is the minimum value is determined as the bias operating point of the phase modulation electrode.
According to the control method for the bias working point of the modulator, the disturbance signal related to the bias voltage is applied to the phase modulation electrode of the silicon-based optical modulator, the signal component with the same frequency as the disturbance signal in the output signal of the modulator is detected in real time, the initial bias voltage is subjected to feedback adjustment, the bias voltage corresponding to the minimum amplitude of the signal component is taken as the bias working point, and therefore the simple and rapid locking and maintaining of the bias working point of the silicon-based optical modulator can be achieved, the control difficulty is reduced, and meanwhile the control precision is improved.
EXAMPLE III
In coherent optical communication, multi-level amplitude phase modulation plus polarization multiplexing technology is a hot point of research. In the multi-level amplitude phase modulation plus polarization multiplexing technology, an IQ modulator composed of a Dual parallel mach-Zehnder (DPMZ) modulator structure has attracted wide attention as a core optical device of a coherent optical communication system.
In practice, it is usually necessary to bias the IQ modulator at a proper operating point, i.e. the two sub-intensity modulators of the upper and lower arms need to be biased at the lowest point of the transmission curve to achieve carrier suppression, while the sub-phase modulator needs to be controlled at the quadrature point to generate an accurate 90 ° phase shift to ensure the orthogonality of the two IQ branches. In practical use, the I-path and Q-path bias operating points of the IQ modulator have thermal crosstalk influence, so that the I-path and Q-path locking cannot be realized by a single control mode.
For the convenience of understanding the above technical solutions, the embodiments of the present application take an IQ modulator as an example for description.
As shown in fig. 3, an embodiment of the present application provides a method for controlling a bias operating point of a modulator, and as can be seen from the figure, the implementation process may specifically include the following steps:
step S301, according to the bias voltage V of the electrode IIAnd determining a first perturbation signal to be applied to the electrode I.
Here, the first perturbation signal is a time-varying periodic voltage signal, according to the formulaDetermining the amplitude phi of a first perturbation signal to be applied on the electrode I1, wherein ,VIThe bias voltage of the phase modulation electrode I is 1-10% VπThe size after squaring the root, VπIs the half-wave voltage of the modulator, f1Is the frequency of the first perturbation signal and t is time.
Step S302, according to the bias voltage V of the electrode QQAnd determining a second perturbation signal to be applied to the electrode Q.
Here, the second disturbance signal is a voltage signal different from the first disturbance signal in step S201, according to the formulaDetermining the amplitude phi of a second perturbation signal to be applied on said electrode Q2, wherein ,VQThe initial bias voltage of the phase modulation electrode Q is 1-10% VπThe size after squaring the root, VπIs the half-wave voltage of the modulator, f2Is the frequency of the second perturbation signal, t is the time, where the frequency f2And the frequency f in step S3011Are not identical.
Here, the first perturbation signal is applied to the phase modulation electrode I of the IQ modulator and the second perturbation signal is applied to the phase modulation electrode Q of the IQ modulator, so that the phase modulation electrode I and the phase modulation electrode Q can be adjusted simultaneously.
Step S303, respectively detecting the frequency f from the output signals of the output ends of the IQ modulators1Signal component of frequency f2Signal component of frequency f1+f2Of the signal component (c).
Here, the output end of the IQ modulator outputs an optical signal, and the optical signal is subjected to photoelectric conversion and fft (fast Fourier transform) spectrum analysis processing to extract a frequency f1Signal component of frequency f2Signal component of frequency f1+f2Of the signal component (c).
Step S304, adjusting the bias voltage VILet the frequency be f1Is smaller than a first threshold valueIAs a bias operating point of the electrode I.
Here, the first threshold value is set to a minimum value on the transmission curve of the MZ modulator, and since the minimum value on the transmission curve is fixed, it is easy to distinguish, and this value is generally used as a detection criterion in detection.
Here, let the frequency be f1Has a minimum amplitude, i.e. a frequency f1Is the bias voltage V corresponding to the minimum first harmonic component ofIAs a bias operating point of the electrode I, i.e., Null point.
Step S305, adjusting the bias voltage VQLet the frequency be f2Is smaller than a first threshold valueQAs a bias operating point of the electrode Q.
Here, let the frequency be f2Is the minimum value of the amplitude of the signal component of (3)QAs a bias operating point of the electrode Q, i.e., Null point.
Step S306, adjusting the initial bias voltage V corresponding to the Phase modulation electrode PhasePLet the frequency be f1+f2Amplitude of the signal component ofV less than a first thresholdPAs a bias operating point of the electrode Phase.
Here, let the frequency be f1+f2Has a minimum amplitude, i.e. frequency, of the signal component of f1+f2Bias voltage V corresponding to the second harmonic component ofPAs the bias operating point of the electrode Phase, i.e., the Quad point.
It should be noted that the amplitudes of the first harmonic component and the second harmonic component of the disturbance signal are different according to different operating points on the transmission curve: the amplitude of the first harmonic component at the Quad point is the largest, the amplitude of the second harmonic component is the smallest, the amplitude of the second harmonic component at the Null point is the largest, and the amplitude of the first harmonic component is the smallest.
The steps S304 to S306 are respectively used for adjusting the bias voltage VI、VQ and VPAnd determining the bias operating point of each Phase modulation electrode of the IQ modulator, namely adjusting the bias voltages of the I path, the Q path and the Phase path of the IQ modulator to the optimal bias operating point by fine tuning the initial bias voltage of each Phase modulation electrode.
The embodiment of the application provides a method for controlling a bias working point of a modulator, and simultaneously, a first harmonic component and a second harmonic component of a disturbing signal are used for controlling a bias voltage, so that the bias working point, namely a Null point and a Quad point, of a silicon-based optical IQ modulator is locked, the control difficulty is reduced, and the control precision is improved. Meanwhile, the locking of the path I and the path Q is realized through a single control mode, and the influence of thermal crosstalk between bias working points of the path I and the path Q is reduced.
Example four
Currently, in coherent optical communication systems, the materials for manufacturing optical modulators can be mainly classified into three main categories: lithium niobate (LiNbO3), indium phosphide (InP), and silicon nitride (si). Among them, LiNbO3 and InP are relatively mature schemes, and the silicon optical scheme is in the research and exploration stage. LiNbO3 is applied to a super-long-distance transmission network because of its advantages such as linear electro-optical modulation effect and excellent optical performance, but is limited by the characteristics of LiNbO3 material itself, and thus cannot be applied to the fabrication of integrated coherent devices. The complicated process and high cost of InP modulators limit their application. With the rapid development of silicon-based optoelectronic technologies, silicon-based optical modulators have the advantages of smaller size, higher integration density of optical units, higher modulation efficiency, lower cost and the like by relying on the existing Complementary Metal Oxide Semiconductor (CMOS) technology, so that the silicon-based IQ optical modulator receives more and more attention in coherent optical modules.
Since the IQ-modulator is a combination of a plurality of MZ (Mach-Zehnder) modulators. The MZ modulator is composed of two waveguide arms and two Y-shaped branches, and the electric fields on the two waveguide arms are adjusted to enable the transmission speeds of light beams on the two waveguide arms to be different and generate optical path difference, so that the two light beams are interfered, and the modulation of light signals is realized. Fig. 4 is a signal transmission characteristic curve of an MZ modulator according to an embodiment of the present invention, as shown in fig. 4, a curve 41 is a transmission characteristic curve of output optical power of the MZ modulator with a bias voltage, and there are 4 specific positions on the curve 41: a minimum point 411(Null point), a negative-quadrature point 412 (Quad-point), a positive-quadrature point 413(Quad + point) and a Peak point 414(Peak point). To operate the IQ modulator normally, the MZ needs to be maintained at a specific operating point, such as the Quad point and the Null point, i.e., a specific bias voltage needs to be applied to the MZ modulator.
Due to the structure of the MZ modulator, such as environmental stability, mechanical vibration, and changes in environmental temperature, the transmission characteristic curve changes with time, which causes the operating point of the modulator to drift, resulting in unstable operation of the modulator, and brings great influence to practical application. Therefore, it is necessary to adjust the bias voltage loaded on the MZ modulator and track and lock the bias voltage according to the offset of the operating curve of the MZ modulator, so that the MZ modulator stably operates at a specific operating point.
To simplify the analysis, a single MZ modulator is considered first. To stabilize the bias point of the IQ modulator at the optimal operating point, the characteristics of the input and output signals of the MZ modulator at the optimal bias point must be analyzed.
When inputting a signal, the transfer function of the MZ modulator can be written as equation (1):
in the formula (1), t is time, VπIs the half-wave voltage of the modulator, PiIs the input intensity of the modulator, PoIs the output intensity of the modulator, Vb and V0And (t) direct current voltage and sinusoidal voltage loaded on a phase modulation electrode of the modulator respectively.
Let the input signal have the form shown in equation (2) below:
in the formula (2), VbiasFor dc bias voltage, a is constant and ω is angular velocity.
Normalizing formula (1) to P ═ 2P0/PiThen, the formula (2) is substituted into the formula (1), resulting in the following formula (3):
for equation (3), letFurther developed, the following formula (4) is obtained:
P＝1+cosV(t)cosφT-sinV(t)sinφT (4)；
expanding the formula (4) by using Taylor series, and reserving cubic terms to obtain the following formula (5):
will be provided withSubstituting into formula (5) for further treatmentThe following formula (6) is obtained:
the high-order term in the formula (6) is reduced to obtain the following formulas (7) and (8):
for equation (8), the first harmonic component is taken as P(1)The second harmonic component being P(2)The following formulas (9) and (10) are obtained:
therefore, by analyzing the change of the signal along the 4 best positions on the transmission characteristic curve by the above equations (9) and (10) in conjunction with fig. 4, it can be concluded: the first harmonic component of the Quad point is the largest and the second harmonic component is the smallest. Similarly, the second harmonic component at Null point is the largest and the first harmonic component is the smallest.
The simulation results of the above theory are shown in fig. 5 and 6. FIG. 5 shows the FFT simulation result of Null point in the embodiment of the present application, in which the curve 51 shows the frequency of 200HZCurve 52 is the signal at Null point after FFT simulation, and as can be seen from curve 52 in fig. 5, the frequency is 200HZThe first harmonic component (abscissa 200H) of the signal after FFT processingZWhere) is the minimum value 0, and the second harmonic component (400H on the abscissa)ZWhere) the amplitude of the peak is the peak. FIG. 6 shows the FFT simulation result of the Quad point of the present application, in which the curve 61 shows the frequency of 200HZCurve 62 is the signal of the Quad point after the FFT simulationNote that the frequency is 200H, as can be seen from the curve 62 in FIG. 6ZThe first harmonic component (abscissa 200H) of the signal after FFT processingZWhere) is the peak value, and the second harmonic component (abscissa of 400H)ZAt) is a minimum value of 0.
Fig. 7 is a schematic block diagram of a method for controlling a bias operating point of a modulator according to an embodiment of the present invention, as shown in fig. 7, a feedback closed-loop control system commonly used in the control system is adopted in the method for controlling a bias voltage of the modulator according to the embodiment of the present invention, an IQ modulator 71 includes an I-path MZ modulator MZMI 711 and a Q-path MZ modulator MZMQ712, which respectively modulate two quadrature phases of an optical carrier signal output by a laser 72, and a Phase delay unit Phase path 713 ensures orthogonality between the two optical carrier phases. The coupler 731 in the photoelectric conversion module 73 separates a small part of the signal from the IQ optical modulator 71, the signal enters the MPD732 and is converted into an electrical signal, the electrical signal enters the ADC733 and is sampled and processed, the signal is sent to the data processing unit 74, and the corresponding bias voltages V of the MZMI 711, the MZMQ712 and the Phase path 713 are respectively adjusted through the DAC741, the DAC742 and the DAC743I、VQ、VP。
FIG. 8 is a schematic diagram of a method for controlling the bias operating point of the modulator according to the embodiment of the present application, and as shown in FIG. 8, the I-path MZ modulator MZMI 811 of the IQ modulator 81 is loaded in the form ofThe Q-path MZ modulator MZMQ 812 is loaded in the form ofRespectively detecting a frequency f in the output light of the modulator1Signal component of frequency f2Signal component of frequency f1+f2The bias operating points of the I path, the Q path, and the Phase path are locked, respectively.
Fig. 9 is a schematic flowchart of another implementation of a method for controlling a bias operating point of a modulator according to an embodiment of the present application, where as shown in fig. 9, the method includes the following steps:
step S901, allLocal range searching bias point to obtain initial bias voltage V of phase modulation electrode IIInitial bias voltage V of phase modulation electrode QQPhase modulation electrode Phase initial bias voltage VP。
Here, the bias point is searched through the global range, and the most basic method can scan a curve by stepping the bias voltage according to a working curve to respectively obtain Null points of the phase modulation electrode I as the initial bias voltage V of the phase modulation electrode IINull point of phase-modulated electrode Q as its initial bias voltage VQThe Quad point of Phase modulation electrode Phase is used as the initial bias voltage VPNamely, the bias voltages of the I path, the Q path and the Phase path are adjusted to be near the optimal operating point through coarse adjustment.
Step S902, applying the pattern of phase modulation on the phase modulation electrode IOf the disturbance signal.
Here, the frequency f of the disturbance signal1The cutoff frequency of the thermo-optic phase shifter, which should be less than 3dB of the modulator, is chosen, and the amplitude a is about 10% of the half-wave voltage of the thermo-optic phase shifter.
Step S503, applying the pattern ofOf the disturbance signal.
Here, the frequency f of the disturbance signal2Following the selection principle in step S902, but the frequency f2And the frequency f in step S9021Different.
The disturbance signals in the special form in the steps S902 and S903 may be directly generated by a DAC of the single chip microcomputer in a customized manner.
Step S904, the optical signal is converted into an electrical signal by the monitoring photodiode MPD at the output end of the modulator, and sent to the data processing unit.
Step S905, the data processing unit detects the frequency f in real time1Signal component of frequency f2Signal component of frequency f1+f2Signal division ofAmount of the compound (A).
Here, the detection of the respective signal components may be realized by a filter or a data processing unit.
Step S906, fine tuning VISo that the frequency is f1The signal component of (a) is minimized to reach the optimum bias operating point of the phase modulating electrode I.
Here, the initial bias voltage V of the phase-modulating electrode I is trimmedILet the frequency of the output be f1The smallest value of the first harmonic component corresponds to the Null point of the I-way.
Step S907, fine tuning VQSo that the frequency is f2The signal component of (a) is minimal, reaching the optimum bias operating point of the phase modulating electrode Q.
Here, the initial bias voltage V of the phase modulating electrode Q is fine-tunedQLet the frequency of the output be f2The smallest value of the first harmonic component corresponds to the Null point of the Q-way.
Step S908, fine tuning VPSo that the frequency is f1+f2The signal component of (a) is minimized to reach the optimum bias operating point of the Phase modulation electrode Phase.
Here, the initial voltage V of the Phase modulating electrode Phase is finely adjustedPSo that the frequency is f1+f2Has the smallest sum frequency signal component, the sum frequency component f1+f2The second harmonic minimum of (c) corresponds to the Quad point of the Phase path.
For the above steps S906 to S907, in order to eliminate the influence of thermal crosstalk between the I path and the Q path, an iterative locking manner may be adopted to ensure that both the I path and the Q path are at the optimal bias operating point, that is, after the Q path is locked, whether the I path bias voltage is shifted or not must be determined, and if there is a shift, correction is required again. And repeating the loop until the bias voltages of the I path and the Q path are the optimal bias working points, and finally realizing the locking of the bias voltage of the modulator.
In the embodiment of the application, the initial bias voltages of the I path and the Q path of the IQ regulator are respectively appliedAndthe amplitude of the first harmonic component and the second harmonic component of the low-frequency disturbing signal is detected, and the initial bias voltage is adjusted accordingly, so that the modulator can work at the optimal bias point. The purposes of detecting the drift of the bias working point and locking the bias working point are achieved by introducing a special form of disturbance signal and simultaneously utilizing the first harmonic component and the second harmonic component of the disturbance signal.
EXAMPLE five
The embodiment of the application provides a control device for a bias operating point of a modulator, which comprises modules and units included in the modules, and can be realized by a specific circuit.
Fig. 10 is a schematic structural diagram of a control apparatus for controlling a bias operating point of a modulator according to an embodiment of the present application, and as shown in fig. 10, the apparatus 10 includes: a first determination module 101, a detection module 102, and a second determination module 103, wherein:
the first determining module 101 is configured to determine a perturbation signal to be applied to the phase modulation electrode according to an inherent characteristic of the modulator;
the detection module 102, configured to detect a signal component having the same frequency as the disturbance signal from an output signal at the output end of the modulator;
the second determining module 103 is configured to adjust the bias voltage of the phase modulating electrode according to the amplitude of the signal component to determine a bias operating point of the modulator.
In the above apparatus, the first determining module 101 is configured to determine the amplitude Φ of the perturbation signal to be applied to the phase modulating electrode according to the following formula:
wherein ,VbaisIs the bias voltage of the phase modulating electrode, A is a constant, VπFor the half-wave voltage of the modulator, f is the frequency of the disturbance signalThe rate, t, is time.
Here, the disturbance signal can be directly customized and generated by a DAC of the single chip microcomputer.
In the above apparatus, the second determining module 104 includes:
the first adjusting unit is used for carrying out feedback adjustment on the bias voltage of the phase modulation electrode according to the amplitude of the signal component, so that the amplitude of the signal component is smaller than a first threshold value;
and the first determining unit is used for determining a corresponding bias voltage when the amplitude of the signal component is smaller than a first threshold value as a bias working point of the phase modulation electrode.
Here, for the output optical signal of the modulator, spectral analysis may be performed by an FFT algorithm, adjusting the initial bias voltage to observe the amplitude of the FFT-processed signal. And judging whether the bias working point drifts or not by detecting the magnitude of the harmonic component, and controlling the bias of the modulator to be in a target state all the time by using a feedback closed-loop system.
In the above apparatus, the modulator is an IQ modulator, and the phase modulation electrode includes at least electrodes I and Q;
correspondingly, the first determining module 101 includes:
a second determination unit for determining the bias voltage V of the electrode IIDetermining a first perturbation signal to be applied to the electrode I;
a third determination unit for determining the bias voltage V of the electrode QQDetermining a second perturbation signal to be applied to the electrode Q; wherein the frequency of the first disturbing signal is f1The frequency of the second disturbance signal is f2，f1And f2Different;
the detection module 103 includes:
a detection unit for detecting the frequency f from the output signals of the output ends of the modulators respectively1Signal component of frequency f2Signal component of frequency f1+f2Of the signal component (c).
Here, the output optical signal is converted into an electric signal by a monitor photodiode MPD built in the modulator, and then detection extraction of each signal component may be realized by a filter or a data processing unit.
In the above apparatus, the first adjusting unit includes:
a first regulating subunit for regulating the bias voltage VILet the frequency be f1Is smaller than a first threshold valueIAs a bias working point of the electrode I;
a second regulating subunit for regulating the bias voltage VQLet the frequency be f2Is smaller than a first threshold valueQAs a bias operating point of the electrode Q;
a third regulator subunit for regulating the initial bias voltage V corresponding to the Phase-modulating electrode PhasePLet the frequency be f1+f2Is smaller than a first threshold valuePAs a bias operating point of the electrode Phase.
Here, the bias voltages corresponding to electrode I, Q and Phase can be adjusted by 3 DACs, respectively.
The above description of the apparatus embodiments, similar to the above description of the method embodiments, has similar beneficial effects as the method embodiments. For technical details not disclosed in the embodiments of the apparatus of the present application, reference is made to the description of the embodiments of the method of the present application for understanding.
It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units; can be located in one place or distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present application.
In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be separately regarded as one unit, or two or more units may be integrated into one unit; the integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
Those of ordinary skill in the art will understand that: all or part of the steps for realizing the method embodiments can be completed by hardware related to program instructions, the program can be stored in a computer readable storage medium, and the program executes the steps comprising the method embodiments when executed; and the aforementioned storage medium includes: various media that can store program codes, such as a removable Memory device, a Read Only Memory (ROM), a magnetic disk, or an optical disk.
Alternatively, the integrated units described above in the present application may be stored in a computer-readable storage medium if they are implemented in the form of software functional modules and sold or used as independent products. Based on such understanding, the technical solutions of the embodiments of the present application may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing an automatic test line of a device to perform all or part of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a removable storage device, a ROM, a magnetic or optical disk, or other various media that can store program code.
The above description is only for the embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A method of controlling a bias operating point of a modulator, the method comprising:
determining a perturbation signal to be applied to a phase modulation electrode of the modulator according to inherent characteristics of the modulator; wherein the disturbance signal is a time-varying periodic voltage signal;
detecting a signal component having the same frequency as the disturbance signal from an output signal at an output terminal of the modulator;
adjusting a bias voltage of the phase modulating electrode based on the amplitude of the signal component to determine a biased operating point of the modulator.
2. The method of claim 1, wherein said determining a perturbation signal to be applied to said phase modulating electrode based on inherent characteristics of said modulator comprises:
the amplitude Φ of the perturbation signal to be applied to the phase modulating electrodes is determined according to the following formula:
wherein ,VbaisIs the bias voltage of the phase modulating electrode, A is a constant, VπIs the half-wave voltage of the modulator, f is the frequency of the disturbing signal, and t is time.
3. The method of claim 1, wherein said adjusting a bias voltage of said phase modulating electrode to determine a bias operating point of said modulator based on an amplitude of said signal component comprises:
according to the amplitude of the signal component, carrying out feedback adjustment on the bias voltage of the phase modulation electrode to enable the amplitude of the signal component to be smaller than a first threshold value;
and determining the corresponding bias voltage when the amplitude of the signal component is smaller than a first threshold value as the bias working point of the phase modulation electrode.
4. The method of claim 1, said modulator being an IQ modulator, said phase modulating electrodes comprising at least electrodes I and Q;
correspondingly, the determining the disturbing signal to be applied to the phase modulating electrode according to the inherent characteristics of the modulator comprises: root of herbaceous plantAccording to the bias voltage V of the electrode IIDetermining a first perturbation signal to be applied to the electrode I; according to the bias voltage V of the electrode QQDetermining a second perturbation signal to be applied to the electrode Q; wherein the frequency of the first disturbing signal is f1The frequency of the second disturbance signal is f2，f1And f2Different;
the detecting, from the output signal at the output of the modulator, a signal component having the same frequency as the disturbance signal includes: detecting the frequency f from the output signals of the IQ modulators1Signal component of frequency f2Signal component of frequency f1+f2Of the signal component (c).
5. The method according to claim 3 or 4, characterized in that the method further comprises:
adjusting the bias voltage VILet the frequency be f1Is smaller than a first threshold valueIAs a bias working point of the electrode I;
adjusting the bias voltage VQLet the frequency be f2Is smaller than a first threshold valueQAs a bias operating point of the electrode Q;
adjusting bias voltage V corresponding to Phase-modulated electrode PhasePLet the frequency be f1+f2Is smaller than a first threshold valuePAs a bias operating point of the electrode Phase.
6. An apparatus for controlling a bias operating point of a modulator, the apparatus comprising: a first determination module, a detection module, and a second determination module, wherein:
the first determining module is used for determining a disturbing signal to be applied to the phase modulation electrode according to the inherent characteristic of the modulator;
the detection module detects a signal component with the same frequency as the disturbance signal from an output signal of the output end of the modulator;
and the second determining module is used for adjusting the bias voltage of the phase modulation electrode according to the amplitude of the signal component so as to determine the bias operating point of the modulator.
7. The apparatus of claim 6, wherein the first determining module is configured to determine the amplitude Φ of the perturbation signal to be applied to the phase modulating electrode according to the following formula:
wherein ,VbaisIs the bias voltage of the phase modulating electrode, A is a constant, VπIs the half-wave voltage of the modulator, f is the frequency of the disturbing signal, and t is time.
8. The apparatus of claim 6, wherein the second determining module comprises:
the first adjusting unit is used for carrying out feedback adjustment on the bias voltage of the phase modulation electrode according to the amplitude of the signal component, so that the amplitude of the signal component is smaller than a first threshold value;
and the first determining unit is used for determining a corresponding bias voltage when the amplitude of the signal component is smaller than a first threshold value as a bias working point of the phase modulation electrode.
9. The apparatus of claim 6, said modulator being an IQ modulator, said phase modulating electrodes comprising at least electrodes I and Q;
correspondingly, the first determining module includes:
a second determination unit for determining the bias voltage V of the electrode IIDetermining a first perturbation signal to be applied to the electrode I;
a third determination unit for determining the bias voltage V of the electrode QQDetermining a second perturbation signal to be applied to the electrode Q;
wherein the frequency of the first disturbing signal is f1The frequency of the second disturbance signal is f2, wherein ,f1And f2Different;
the detection module comprises:
a detection unit for detecting the frequency f from the output signals of the output ends of the modulators respectively1Signal component of frequency f2Signal component of frequency f1+f2Of the signal component (c).
10. The apparatus according to claim 8 or 9, wherein the first adjusting unit comprises:
a first regulating subunit for regulating the bias voltage VILet the frequency be f1Is smaller than a first threshold valueIAs a bias working point of the electrode I;
a second regulating subunit for regulating the bias voltage VQLet the frequency be f2Is smaller than a first threshold valueQAs a bias operating point of the electrode Q;
a third regulator subunit for regulating the bias voltage V corresponding to the Phase-modulating electrode PhasePLet the frequency be f1+f2Is smaller than a first threshold valuePAs a bias operating point of the electrode Phase.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112468226A (en) * | 2020-11-27 | 2021-03-09 | 武汉邮电科学研究院有限公司 | IQ modulator parameter monitoring method and system based on perturbation electric signal |
| CN112564807A (en) * | 2020-12-02 | 2021-03-26 | 武汉光迅科技股份有限公司 | Method and device for controlling bias voltage of optical modulator |
| CN113114376A (en) * | 2021-03-26 | 2021-07-13 | 广东九联科技股份有限公司 | Optical module of top-modulated signal based on phase modulation and communication method |
| CN115459853A (en) * | 2022-08-26 | 2022-12-09 | 武汉烽火技术服务有限公司 | Automatic bias control method, device, equipment and storage medium for optical IQ modulator |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101364841A (en) * | 2007-08-10 | 2009-02-11 | 华为技术有限公司 | Bias control method and system for multiple MZ modulator |
| CN103873152A (en) * | 2012-12-18 | 2014-06-18 | 武汉邮电科学研究院 | Automatic bias voltage control system and method for light IQ modulator |
| US20140294401A1 (en) * | 2013-03-27 | 2014-10-02 | Electronics And Telecommunications Research Institute | Optical transmitter and method thereof |
| US20160282638A1 (en) * | 2015-03-24 | 2016-09-29 | Finisar Corporation | Automatic bias stabilization of dual-polarization in-phase and quadrature optical modulator |
| CN106154592A (en) * | 2016-08-31 | 2016-11-23 | 武汉光迅科技股份有限公司 | The autobias control method of MZI type IQ electrooptic modulator in parallel and device thereof |
| CN106549714A (en) * | 2016-10-31 | 2017-03-29 | 武汉光迅科技股份有限公司 | A kind of control method and control device based on IQ electrooptic modulator quadrature voltages |
| CN106685871A (en) * | 2016-12-09 | 2017-05-17 | 华中科技大学 | A control method and system for an IQ modulator |
| CN106773144A (en) * | 2016-12-20 | 2017-05-31 | 武汉光迅科技股份有限公司 | A kind of voltage processing method and its device for the control of silicon light modulators autobias |
| CN107132713A (en) * | 2016-02-29 | 2017-09-05 | 住友大阪水泥股份有限公司 | Optical modulator and the light sending device using optical modulator |
| US20170359122A1 (en) * | 2015-02-14 | 2017-12-14 | Plugtech Precision Systems Limited (Shenzhen) | Method and apparatus for digitally and automatically controlling a bias voltage of electro-optic optical modulator |
-
2019
- 2019-09-18 CN CN201910883568.5A patent/CN110596918B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101364841A (en) * | 2007-08-10 | 2009-02-11 | 华为技术有限公司 | Bias control method and system for multiple MZ modulator |
| CN103873152A (en) * | 2012-12-18 | 2014-06-18 | 武汉邮电科学研究院 | Automatic bias voltage control system and method for light IQ modulator |
| US20140294401A1 (en) * | 2013-03-27 | 2014-10-02 | Electronics And Telecommunications Research Institute | Optical transmitter and method thereof |
| US20170359122A1 (en) * | 2015-02-14 | 2017-12-14 | Plugtech Precision Systems Limited (Shenzhen) | Method and apparatus for digitally and automatically controlling a bias voltage of electro-optic optical modulator |
| US20160282638A1 (en) * | 2015-03-24 | 2016-09-29 | Finisar Corporation | Automatic bias stabilization of dual-polarization in-phase and quadrature optical modulator |
| CN107132713A (en) * | 2016-02-29 | 2017-09-05 | 住友大阪水泥股份有限公司 | Optical modulator and the light sending device using optical modulator |
| CN106154592A (en) * | 2016-08-31 | 2016-11-23 | 武汉光迅科技股份有限公司 | The autobias control method of MZI type IQ electrooptic modulator in parallel and device thereof |
| CN106549714A (en) * | 2016-10-31 | 2017-03-29 | 武汉光迅科技股份有限公司 | A kind of control method and control device based on IQ electrooptic modulator quadrature voltages |
| CN106685871A (en) * | 2016-12-09 | 2017-05-17 | 华中科技大学 | A control method and system for an IQ modulator |
| CN106773144A (en) * | 2016-12-20 | 2017-05-31 | 武汉光迅科技股份有限公司 | A kind of voltage processing method and its device for the control of silicon light modulators autobias |
Non-Patent Citations (1)
| Title |
|---|
| 陈宏刚等: "同相正交硅基光调制器的自动偏置电压控制技术" * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112468226A (en) * | 2020-11-27 | 2021-03-09 | 武汉邮电科学研究院有限公司 | IQ modulator parameter monitoring method and system based on perturbation electric signal |
| CN112468226B (en) * | 2020-11-27 | 2022-04-29 | 武汉邮电科学研究院有限公司 | IQ modulator parameter monitoring method and system based on perturbation electric signal |
| CN112564807A (en) * | 2020-12-02 | 2021-03-26 | 武汉光迅科技股份有限公司 | Method and device for controlling bias voltage of optical modulator |
| CN112564807B (en) * | 2020-12-02 | 2022-04-08 | 武汉光迅科技股份有限公司 | Method and device for controlling bias voltage of optical modulator |
| CN113114376A (en) * | 2021-03-26 | 2021-07-13 | 广东九联科技股份有限公司 | Optical module of top-modulated signal based on phase modulation and communication method |
| CN115459853A (en) * | 2022-08-26 | 2022-12-09 | 武汉烽火技术服务有限公司 | Automatic bias control method, device, equipment and storage medium for optical IQ modulator |
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