CN105871770B - Method and device for controlling bias point voltage of modulator - Google Patents
Method and device for controlling bias point voltage of modulator Download PDFInfo
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- CN105871770B CN105871770B CN201510037240.3A CN201510037240A CN105871770B CN 105871770 B CN105871770 B CN 105871770B CN 201510037240 A CN201510037240 A CN 201510037240A CN 105871770 B CN105871770 B CN 105871770B
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Abstract
The invention discloses a method and a device for controlling the bias point voltage of a modulator, wherein the method comprises the following steps: acquiring a first voltage value of a preset bias point, and sending the first voltage value to a modulator; acquiring a first average optical power of a first feedback optical signal of a modulator; repeatedly executing the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to be a second voltage value by a preset step length, and sending the second voltage value to the modulator; acquiring a second average optical power of a second feedback optical signal of the modulator; if the difference value between the second average light power and the first average light power is smaller than a preset threshold, taking the second voltage value as a voltage value meeting a preset condition; and sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point. The invention at least solves the problem that the modulator in the related art needs a plurality of pilot signals, so that a control loop is complex.
Description
Technical Field
The invention relates to the field of communication, in particular to a method and a device for controlling bias point voltage of a modulator.
Background
Since the advent of optical fiber communication, the development has been directed to ultra-high speed systems and ultra-large capacity wavelength division multiplexing systems. People pursue higher speed and larger capacity systems without stopping, and with the large-scale commercial use of 100G Polarization-multiplexed Quadrature Phase Shift Keying (PM-QPSK) systems, super 100G systems enter the visual field of people. An optical phase Modulation method represented by a 16QAM (Quadrature Amplitude Modulation) system is receiving increasing attention in the industry. The 16-system quadrature amplitude modulation method is a modulation mode combining amplitude modulation and phase modulation, the frequency spectrum utilization rate of the 16-system quadrature amplitude modulation method is 4 bit/s-Hz which is twice of QPSK, the capacity of the whole system can be doubled, and the requirement of high-speed communication in the future can be met.
In a brand new 16QAM modulation system, since the euclidean distance of a constellation point (also called a vector end point) is relatively short, the accuracy and stability of a bias point of a modulator are important to ensure good system performance. The 16QAM system modulator adopts a lithium niobate modulator. The transmission characteristic or the bias point of the lithium niobate modulator can change along with the change of temperature and stress due to the characteristics of the material of the lithium niobate modulator, so that the bias point of the lithium niobate modulator is required to be kept real-time, accurate and stable by a certain method.
At present, like the QPSK modulation system, the method for controlling the bias point of the modulator for the 16QAM modulation system is to add pilot signals of various frequencies to the modulation signal of the lithium niobate modulator, and then separate and analyze the information of these pilot signals or their difference frequency signals from the output modulation signal, thereby controlling the stability of the bias point. The control loop is complicated by the need for multiple pilot signals, while the pilot signal itself implies a limited stability of the bias point.
In order to solve the problem that a modulator in the related art needs a plurality of pilot signals, which makes a control loop complicated, no effective solution has been proposed.
Disclosure of Invention
The invention provides a method and a device for controlling bias point voltage of a modulator, which at least solve the problem that the modulator needs a plurality of pilot signals in the related art, so that a control loop is complex.
According to one aspect of the invention, there is provided a method of controlling a modulator bias point voltage, comprising:
acquiring a first voltage value of a preset bias point, and sending the first voltage value to a modulator;
obtaining a first average optical power of a first feedback optical signal of the modulator, the first feedback optical signal corresponding to the first voltage value;
repeatedly executing the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to a second voltage value by a predetermined step size, and sending the second voltage value to the modulator; obtaining a second average optical power of a second feedback optical signal of the modulator, the second feedback optical signal corresponding to the second voltage value; if the difference value between the second average light power and the first average light power is smaller than a preset threshold, taking the second voltage value as the voltage value meeting the preset condition;
and sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point.
Preferably, if the difference between the second average optical power and the first average optical power is not less than the preset threshold, the second voltage value is adjusted to a third voltage value by the preset step length, and the third voltage value is sent to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value.
Preferably, if the second voltage value is obtained by increasing the first voltage value by the predetermined step length, the third voltage value is obtained by increasing the second voltage value by the predetermined step length; and if the second voltage value is the voltage value obtained by reducing the first voltage value by the preset step length, the third voltage value is the voltage value obtained by reducing the second voltage value by the preset step length.
Preferably, the obtaining the first average optical power of the first feedback optical signal of the modulator includes:
receiving an output optical signal from the modulator;
splitting the output optical signal into a first output optical signal for output by the modulator, and the first feedback optical signal;
performing photoelectric conversion on the first feedback optical signal to obtain an electrical signal corresponding to the first feedback optical signal;
and obtaining the first average optical power according to the electric signal.
Preferably, the method for controlling the bias point voltage of the modulator further comprises:
and storing the voltage value meeting the preset condition.
According to another aspect of the present invention, there is provided a control apparatus for a bias point voltage of a modulator, comprising: the first acquisition module is used for acquiring a first voltage value of a preset bias point and sending the first voltage value to the modulator;
a second obtaining module, configured to obtain a first average optical power of a first feedback optical signal of the modulator, where the first feedback optical signal corresponds to the first voltage value;
the processing module is used for repeatedly executing the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to a second voltage value by a predetermined step size, and sending the second voltage value to the modulator; obtaining a second average optical power of a second feedback optical signal of the modulator, the second feedback optical signal corresponding to the second voltage value; if the difference value between the second average light power and the first average light power is smaller than a preset threshold, taking the second voltage value as the voltage value meeting the preset condition;
and the control module is used for sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point.
Preferably, the processing module is further configured to adjust the second voltage value to a third voltage value according to the predetermined step length if the difference between the second average optical power and the first average optical power is not smaller than the preset threshold, and send the third voltage value to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value.
Preferably, if the second voltage value is obtained by increasing the first voltage value by the predetermined step length, the third voltage value is obtained by increasing the second voltage value by the predetermined step length; and if the second voltage value is the voltage value obtained by reducing the first voltage value by the preset step length, the third voltage value is the voltage value obtained by reducing the second voltage value by the preset step length.
Preferably, the second obtaining module includes:
a receiving unit for receiving the output optical signal from the modulator;
an optical coupling unit, configured to divide the output optical signal into a first output optical signal for output by the modulator, and the first feedback optical signal;
the photoelectric conversion unit is used for performing photoelectric conversion on the first feedback optical signal to obtain an electric signal corresponding to the first feedback optical signal;
and the optical power detection unit is used for obtaining the first average optical power according to the electric signal.
Preferably, the control device of the modulator bias point voltage further includes:
and the storage unit is used for storing the voltage value meeting the preset condition.
According to the invention, after the first voltage value of the preset bias point is acquired and sent to the modulator, and the first average optical power of the first feedback optical signal of the modulator corresponding to the first voltage value is acquired, the following operations are repeatedly executed until the voltage value meeting the preset condition is obtained: adjusting the first voltage value of the bias point to a second voltage value by a predetermined step size, and sending the second voltage value to the modulator; obtaining a second average optical power of a second feedback optical signal of the modulator, the second feedback optical signal corresponding to the second voltage value; if the difference value between the second average optical power and the first average optical power is smaller than a preset threshold, the second voltage value is used as the voltage value meeting the preset condition, and then the voltage value meeting the preset condition is sent to the modulator to control the voltage of the bias point.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a flow chart of a method of controlling a modulator bias point voltage according to an embodiment of the present invention;
FIG. 2 is a block diagram of a control apparatus for modulator bias point voltage according to an embodiment of the present invention;
FIG. 3 is a block diagram of another modulator bias point voltage control arrangement according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of another modulator bias point voltage control apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the hardware configuration of the control apparatus for the modulator bias point voltage according to the preferred embodiment of the present invention;
FIG. 6a is a flow chart illustrating a method for controlling the bias point voltage of the modulator according to the present invention;
fig. 6b is another flow chart of a method of controlling the modulator bias point voltage implemented in accordance with the present invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
In the present embodiment, a method for controlling a bias point voltage of a modulator is provided, and fig. 1 is a flowchart of a method for controlling a bias point voltage of a modulator according to an embodiment of the present invention, as shown in fig. 1, the flowchart includes the following steps:
step S102, acquiring a first voltage value of a preset bias point, and sending the first voltage value to a modulator;
step S104, obtaining a first average optical power of a first feedback optical signal of the modulator, wherein the first feedback optical signal corresponds to a first voltage value;
step S106, repeatedly performing the following operations until a voltage value satisfying a preset condition is obtained: adjusting the first voltage value of the bias point to be a second voltage value by a preset step length, and sending the second voltage value to the modulator; acquiring a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to a second voltage value; if the difference value between the second average light power and the first average light power is smaller than a preset threshold, taking the second voltage value as a voltage value meeting a preset condition;
and step S108, sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point.
Through the steps, whether the voltage value input to the modulator is adjusted or not is judged according to the difference value of the first average optical power and the first average optical power, compared with the prior art that pilot signals with various frequencies are required to be added into modulation signals, the problem that a control loop is complex is solved, the problem that the modulator in the prior art needs a plurality of pilot signals and the control loop is complex is solved through a mode of not adding any pilot signal, the effects of low cost, simple control loop and high stability are achieved, and the control of bias point voltage can be achieved.
Preferably, if the difference between the second average optical power and the first average optical power is not less than the preset threshold, the second voltage value is adjusted to a third voltage value by a predetermined step length, and the third voltage value is sent to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value. Namely, under the condition that the difference value between the second average optical power and the first average optical power is not less than the preset threshold, the voltage value is continuously adjusted, so that the voltage of the optimal bias point is quickly and effectively determined.
Preferably, if the second voltage value is obtained by increasing the first voltage value by a predetermined step length, the third voltage value is obtained by increasing the second voltage value by a predetermined step length; if the second voltage value is a voltage value obtained by reducing the first voltage value by a predetermined step length, the third voltage value is a voltage value obtained by reducing the second voltage value by a predetermined step length. That is, under the condition that the difference between the second average optical power and the first average optical power is not less than the preset threshold, the voltage value can be adjusted by the same step length, so that the voltage of the optimal bias point can be determined quickly and effectively.
Preferably, obtaining the first average optical power of the first feedback optical signal of the modulator comprises: receiving an output optical signal from a modulator; splitting the output optical signal into a first output optical signal for output by the modulator, and a first feedback optical signal; performing photoelectric conversion on the first feedback optical signal to obtain an electric signal corresponding to the first feedback optical signal; and obtaining the first average optical power according to the electrical signal. I.e. detection of the average optical power is achieved by photoelectric conversion.
Preferably, the method for controlling the bias point voltage of the modulator according to the embodiment of the present invention further includes: and storing the voltage value meeting the preset condition. The voltage value is stored in the ROM and is directly called for use when the power is powered on next time.
According to the embodiment of the invention, after the first voltage value of the preset bias point is obtained and sent to the modulator, and the first average optical power of the first feedback optical signal of the modulator corresponding to the first voltage value is obtained, the following operations are repeatedly executed until the voltage value meeting the preset condition is obtained: adjusting the first voltage value of the bias point to be a second voltage value by a preset step length, and sending the second voltage value to the modulator; acquiring a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to a second voltage value; if the difference value between the second average luminous power and the first average luminous power is smaller than the preset threshold, the second voltage value is used as a voltage value meeting the preset condition, and then the voltage value meeting the preset condition is sent to the modulator to control the voltage of the bias point.
In this embodiment, a control device for a bias point voltage of a modulator is further provided, and the device is used to implement the foregoing embodiments and preferred embodiments, and the description of the device is omitted. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.
Fig. 2 is a block diagram of a control apparatus for a bias point voltage of a modulator according to an embodiment of the present invention, as shown in fig. 2, the apparatus including:
the first obtaining module 202 is configured to obtain a first voltage value of a preset bias point, and send the first voltage value to the modulator;
a second obtaining module 204, configured to obtain a first average optical power of a first feedback optical signal of the modulator, where the first feedback optical signal corresponds to a first voltage value;
a processing module 206, configured to repeatedly perform the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to be a second voltage value by a preset step length, and sending the second voltage value to the modulator; acquiring a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to a second voltage value; if the difference value between the second average light power and the first average light power is smaller than a preset threshold, taking the second voltage value as a voltage value meeting a preset condition;
and a control module 208 for sending the voltage value meeting the preset condition to the modulator to control the voltage of the bias point.
Preferably, the processing module 206 is further configured to adjust the second voltage value to a third voltage value by a predetermined step length if the difference between the second average optical power and the first average optical power is not less than a preset threshold, and send the third voltage value to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value.
Preferably, if the second voltage value is obtained by increasing the first voltage value by a predetermined step length, the third voltage value is obtained by increasing the second voltage value by a predetermined step length; if the second voltage value is a voltage value obtained by reducing the first voltage value by a predetermined step length, the third voltage value is a voltage value obtained by reducing the second voltage value by a predetermined step length.
Preferably, as shown in fig. 3, the second obtaining module 204 includes:
a receiving unit 302 for receiving an output optical signal from the modulator;
an optical coupling unit 304 for dividing the output optical signal into a first output optical signal for output by the modulator, and a first feedback optical signal;
a photoelectric conversion unit 306, configured to perform photoelectric conversion on the first feedback optical signal to obtain an electrical signal corresponding to the first feedback optical signal;
the optical power detection unit 308 is configured to obtain a first average optical power according to the electrical signal.
Preferably, as shown in fig. 4, the apparatus for controlling a bias point voltage of a modulator according to an embodiment of the present invention further includes:
the storage unit 402 is used for storing a voltage value meeting a preset condition.
According to the embodiment of the invention, after the first voltage value of the preset bias point is obtained and sent to the modulator, and the first average optical power of the first feedback optical signal of the modulator corresponding to the first voltage value is obtained, the following operations are repeatedly executed until the voltage value meeting the preset condition is obtained: adjusting the first voltage value of the bias point to be a second voltage value by a preset step length, and sending the second voltage value to the modulator; acquiring a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to a second voltage value; if the difference value between the second average luminous power and the first average luminous power is smaller than the preset threshold, the second voltage value is used as a voltage value meeting the preset condition, and then the voltage value meeting the preset condition is sent to the modulator to control the voltage of the bias point.
The technical problem to be solved by the embodiment of the invention is as follows: the method and the device for controlling the offset point of the 16QAM system modulator have the advantages of low cost, easiness in realization, simple control loop and high stability, so that the offset point of the 16QAM system modulator is relatively stable and is simply controlled, and the stability of the system is improved.
The embodiment of the invention also provides a method for controlling the offset point of the modulator in the 16QAM modulation system, which comprises the following steps:
In-phase/Quadrature (I/Q) bias is controlled to a correct position by detecting a Photodiode (PD) minimum value, and phase bias is controlled to a correct position by detecting a PIN (positive-Intrinsic-negative) minimum value.
The embodiment of the invention provides a control device for a modulator bias point in a 16QAM (quadrature amplitude modulation) modulation system, which comprises the following components:
optical coupler (coupler): 95/5, wherein the output light is 95% and the feedback light is 5%.
A PIN tube: and the bandwidth is 10G, and photoelectric conversion is realized in a feedback loop.
Radio Frequency Power Detector (Radio Frequency Power Detector, RFPD for short): the Root mean Square value-Direct Current (RMS-DC) chip mainly functions to convert the effective value of a signal into Direct Current for output.
Analog-to-Digital Converter (ADC): the analog quantity of the feedback optical path is converted into digital quantity.
Digital-to-Analog Converter (DAC): the digital quantity output by the digital arithmetic unit is converted into an analog signal.
And the Micro Control Unit/digital signal processing (MCU/DSP) is used for implementing a feedback Control algorithm.
The embodiment of the invention provides a scheme for controlling the bias point of a low-cost 16QAM modulator based on digital processing, which has the following beneficial effects:
the method for controlling the 16QAM modulator bias point of the embodiment of the invention adopts the modes of average power detection and digital processing, and can realize the relative stability of the 16QAM modulator bias point. Compared with the control method of other systems, the invention does not need to add any pilot signal, has the advantages of simple structure, easy realization, high precision, high reliability, high responsivity, flexible and simple control loop and the like, and achieves the effects of more convenient control of the offset point of the 16QAM modulator and being beneficial to debugging.
The novel 16QAM modulator system comprises an optical coupler, a PIN tube, a radio frequency power detector, an analog-to-digital converter, a digital-to-analog converter and a digital algorithm processing unit module, can quickly, stably and accurately realize the locking of the bias point of the 16QAM modulator, is not limited by the built-in PD bandwidth of the modulator, and has important significance for the transmission of a super 100G dense wavelength division system.
In order to implement the above control solution, the following preferred embodiment is given in the example of the present invention, as shown in fig. 5. Firstly, an optical signal emitted from a laser is divided into EV and EH by a polarization beam splitter (PBS for short), the EV and the EH are respectively divided into I light and Q light by a first 3dB coupler and a second 3dB coupler, wherein the I light of the EV is converted into IV light by a first interference type (Mach-Zehnder, MZ for short) modulator modulated by a first driver controlled by DAC _ V; the Q light of the EV passes through a second MZ modulator modulated by a first driver controlled by DAC _ V and a first 90-degree phase delay unit to become QV light; the I light of the EH passes through a third MZ modulator modulated by a second driver controlled by DAC _ H to become IH light; the Q light of the EH passes through a fourth MZ modulator modulated by a second driver controlled by DAC _ H and a second 90-degree phase delay unit to become QH light; secondly, IV light and QV light, IH light and QH light are respectively coupled by a third 3dB coupler and synthesized by a fourth 3dB coupler, then are synthesized into a beam of light by PBC through a second polarization beam splitter, and are divided into output light E through a coupler of 5:951OUT and feedback light; the two high-precision ADCs are used for collecting the V-path light and the H-path light respectively detected by the two built-in PDs to a Digital Signal Processing chip (DSP), the DSP adjusts bias point feedback control signals and converts the bias point feedback control signals into analog voltage signals through the DAC respectively to control bias points of the first MZ modulator, the second MZ modulator, the third MZ modulator and the fourth MZ modulator respectively, and therefore the average power finally detected is the minimum. Finally, the correct bias of the IQ bias point of the 16QAM modulator can be obtained.
The output light is divided into output light and feedback light through an 5/95 coupler, wherein 95% of the output light is used for final 16QAM modulation output, 5% of the output light is subjected to photoelectric conversion through a 10G PIN tube, then an effective value of a signal is converted into direct current output through an RFPD, the power is collected to a digital signal processing chip DSP by a high-precision ADC, a feedback control signal of a bias point is adjusted by the DSP and converted into an analog voltage signal through a DAC to control the bias point of the 16QAM modulator, the finally detected average power is minimum, and correct bias of a phase bias point of the 16QAM modulator can be obtained.
The embodiment of the invention realizes the digital algorithm flow chart of the bias point control of the 16QAM modulator in the DSP, as shown in fig. 6a and fig. 6 b:
first, first power-on
1. Initializing bias points of a 16QAM modulator: the DSP issues a bias point median value (generally 3.5V) to be respectively issued to the path I and the path Q through the DAC, the ADC is used for collecting output optical signals detected by the PD, and the DSP reads ADC data to be used as an initial average optical power value.
2. And increasing/decreasing the voltage value of the bias point according to the step size of 0.05V (different settings can be set according to the actual bias precision and the modulation rate requirement), issuing the voltage value again through the DSP, and reading the ADC value at the moment as a new average light power value.
3. The DSP compares the new average light power value with the initial average light power value. If the new value is smaller than the initial value, the new average light power value is used as the initial average light power value, the voltage value of the bias point is continuously increased/decreased, and the step 2 is repeated; if the new value is larger than the initial value, the initial average optical power value is kept unchanged, the voltage value of the bias point is reduced/increased, and the ADC value is read as the new average optical power value.
4. Repeating step 3 to make the new average optical power value minus the initial optical power value less than a certain small amount (expressed by voltage, generally considered to be less than 0.001V), the bias point at this time is the optimum bias point. And storing the offset point into a ROM of the DSP, and directly calling for use when the DSP is powered on next time.
5. And repeating the step 3, and following the change of the bias point so as to ensure that the real-time bias point is at a proper position.
Second, power up again
1. And calling and issuing the value of the bias point saved last time in the ROM of the DSP.
2. And repeating the step 2 and the step 3 of the initial power-on, and keeping following the optimal bias point.
In the embodiment of the present invention, the relationship between the 16QAM signal amplitudes: relative to DAC output, the I/Q circuit has two voltage amplitudes respectively, so that the high voltage V isHI，VHQLow voltage VLI，VLQ. In the ideal case:
and automatically controlling an I/Q bias point: for the case of the I-path signal,
wherein the content of the first and second substances,
respectively representing the phase, V, of the constellation points of the first and second layers of the constellation diagramπRefers to the voltage required for the modulator to change phase by pi.
The light power is detected by the PD of the modulator, and the average light power of the path I can be obtained as follows:
wherein the content of the first and second substances,
in order to bias the phase of the point,
statistics show that the probability of each signal occurring is the same, so it is reasonable to use equation (2) to find the optical power.
When combined with the formula (1), then
Therefore, the first and second electrodes are formed on the substrate,
the bias point is at the lowest point, and the average optical power has the minimum value; then by feedback, the best bias point, i.e. the bias point lowest point, can be obtained by minimizing the average output optical power. In the same way, the Q-way bias point is the same.
Therefore, the PD obtains the optimal IQ bias point when detecting the minimum optical power.
Phase control: from equation (1), the bias point is at the lowest point for an ideal input signal:
wherein, when the two paths of signals of I/Q are the same, the plus value is taken out, and when the opposite is taken out, the minus value is taken outIIndicating the voltage of the I path, VbIIndicating the bias voltage, V, of the path IQRepresenting the voltage of the Q path, VbQWhich represents the bias voltage of the Q-path,
indicating the phase difference between I and Q.
For the output V, H two paths of 16QAM debugging signals, the effective power of the detected RF signal is proportional to:
wherein the content of the first and second substances,
and
representing the phase operating points for the V and H polarization states, respectively.
Therefore, if the output optical signal of the modulator is detected by the PIN tube, an amplitude AND is obtained
Is in direct proportionA Non-Return to Zero (NRZ) signal whose rate is the rate of the modulation signal. The power of the signal within a certain bandwidth is detected and the control of the phase offset point is achieved by changing the position of the phase offset point to a minimum.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of controlling a bias point voltage of a modulator, comprising:
acquiring a first voltage value of a preset bias point, and sending the first voltage value to a modulator;
obtaining a first average optical power of a first feedback optical signal of the modulator, the first feedback optical signal corresponding to the first voltage value;
repeatedly executing the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to a second voltage value by a preset step length, sending the second voltage value to the modulator, obtaining a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to the second voltage value, and if the difference between the second average optical power and the first average optical power is smaller than a preset threshold, taking the second voltage value as the voltage value meeting a preset condition;
and sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point.
2. The method according to claim 1, wherein if the difference between the second average optical power and the first average optical power is not less than the preset threshold, the second voltage value is adjusted to a third voltage value by the predetermined step size, and the third voltage value is sent to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value.
3. The method according to claim 2, wherein if the second voltage value is a voltage value obtained by increasing the first voltage value by the predetermined step, the third voltage value is a voltage value obtained by increasing the second voltage value by the predetermined step; and if the second voltage value is the voltage value obtained by reducing the first voltage value by the preset step length, the third voltage value is the voltage value obtained by reducing the second voltage value by the preset step length.
4. The method of claim 1, wherein obtaining the first average optical power of the first feedback optical signal of the modulator comprises:
receiving an output optical signal from the modulator;
splitting the output optical signal into a first output optical signal for output by the modulator, and the first feedback optical signal;
performing photoelectric conversion on the first feedback optical signal to obtain an electrical signal corresponding to the first feedback optical signal;
and obtaining the first average optical power according to the electric signal.
5. The method of any of claims 1 to 4, further comprising:
and storing the voltage value meeting the preset condition.
6. An apparatus for controlling a bias point voltage of a modulator, comprising:
the first acquisition module is used for acquiring a first voltage value of a preset bias point and sending the first voltage value to the modulator;
a second obtaining module, configured to obtain a first average optical power of a first feedback optical signal of the modulator, where the first feedback optical signal corresponds to the first voltage value;
the processing module is used for repeatedly executing the following operations until a voltage value meeting a preset condition is obtained: adjusting the first voltage value of the bias point to a second voltage value by a preset step length, sending the second voltage value to the modulator, obtaining a second average optical power of a second feedback optical signal of the modulator, wherein the second feedback optical signal corresponds to the second voltage value, and if the difference between the second average optical power and the first average optical power is smaller than a preset threshold, taking the second voltage value as the voltage value meeting a preset condition;
and the control module is used for sending the voltage value meeting the preset condition to the modulator so as to control the voltage of the bias point.
7. The apparatus according to claim 6, wherein the processing module is further configured to adjust the second voltage value to a third voltage value according to the predetermined step size if the difference between the second average optical power and the first average optical power is not smaller than the preset threshold, and send the third voltage value to the modulator, so as to obtain a third average optical power of a third feedback optical signal of the modulator, where the third feedback optical signal corresponds to the third voltage value.
8. The apparatus according to claim 7, wherein if the second voltage value is a voltage value obtained by increasing the first voltage value by the predetermined step, the third voltage value is a voltage value obtained by increasing the second voltage value by the predetermined step; and if the second voltage value is the voltage value obtained by reducing the first voltage value by the preset step length, the third voltage value is the voltage value obtained by reducing the second voltage value by the preset step length.
9. The apparatus of claim 6, wherein the second obtaining module comprises:
a receiving unit for receiving the output optical signal from the modulator;
an optical coupling unit, configured to divide the output optical signal into a first output optical signal for output by the modulator, and the first feedback optical signal;
the photoelectric conversion unit is used for performing photoelectric conversion on the first feedback optical signal to obtain an electric signal corresponding to the first feedback optical signal;
and the optical power detection unit is used for obtaining the first average optical power according to the electric signal.
10. The apparatus of any one of claims 6 to 9, further comprising:
and the storage unit is used for storing the voltage value meeting the preset condition.
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| CN201510037240.3A CN105871770B (en) | 2015-01-23 | 2015-01-23 | Method and device for controlling bias point voltage of modulator |
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| CN106301554B (en) | 2016-08-31 | 2019-01-22 | 武汉光迅科技股份有限公司 | A kind of adjustment method and debugging apparatus of parallel connection MZI electrooptical modulator quiescent potential |
| CN108306689B (en) * | 2018-01-13 | 2020-08-11 | 西安电子科技大学 | Automatic bias control method for any point of double parallel Mach-Zehnder modulator (DPMZM) based on three pilot frequencies |
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| CN101859156A (en) * | 2010-05-14 | 2010-10-13 | 南京大学 | Bias voltage control device of electrooptic modulator and control method thereof |
| CN101909029A (en) * | 2010-07-14 | 2010-12-08 | 中兴通讯股份有限公司 | Method and system for controlling bias points of DQPSK (Differential Quadrature Reference Phase Shift Keying) modulator |
| WO2013164603A1 (en) * | 2012-05-02 | 2013-11-07 | Bae Systems Plc | Controlling bias voltages for optical modulators |
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| CN101859156A (en) * | 2010-05-14 | 2010-10-13 | 南京大学 | Bias voltage control device of electrooptic modulator and control method thereof |
| CN101909029A (en) * | 2010-07-14 | 2010-12-08 | 中兴通讯股份有限公司 | Method and system for controlling bias points of DQPSK (Differential Quadrature Reference Phase Shift Keying) modulator |
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