A method and apparatus for calibrating a coherent optical module based on photocurrent detection
By acquiring the responsivity of the transmitter and receiver of the coherent optical module at different wavelengths and temperatures, calculating the target sampling value using the probe photocurrent, and adjusting the output and input parameters of the coherent optical module, the problem of inconsistent calibration methods for different models of coherent optical modules is solved, achieving fast and efficient calibration and precise control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ACCELINK TECHNOLOGIES CO LTD
- Filing Date
- 2023-03-17
- Publication Date
- 2026-07-14
AI Technical Summary
The calibration methods for different models of coherent optical modules are not uniform, resulting in low calibration efficiency and insufficient accuracy.
By acquiring the responsivity of the transmitter and receiver at different wavelengths and temperatures, the target sampling value is calculated using the probe photocurrent. The output and input parameters of the coherent optical module are adjusted to make the actual sampling value close to the target value. Calibration is performed using a calibration device that includes a transmitter power measurement device, a test light source, an amplifier device, a filter device, and a receiver power measurement device.
It enables rapid calibration of different types of coherent optical modules, improves calibration efficiency and accuracy, and enhances the control precision of coherent optical modules across the entire power range.
Smart Images
Figure CN116318417B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of optical fiber technology, and in particular to a calibration method and apparatus for a coherent optical module based on photocurrent detection. Background Technology
[0002] In the use of coherent optical modules, relevant parameters need to be adjusted based on the output optical power reported by the transmitter and the input optical power reported by the receiver. To ensure accurate reporting of the output optical power and input optical power, the transmitter and receiver of the coherent optical module need to be calibrated.
[0003] Because different coherent optical modules are manufactured using different processes, fixed calibration parameters may not be applicable to every coherent module. Therefore, different calibration schemes need to be designed for different coherent optical modules to improve calibration efficiency and control accuracy across the entire power range of the coherent optical module.
[0004] Therefore, how to overcome the shortcomings of existing technologies and solve the problem of inconsistent calibration methods for different types of coherent optical modules is a problem to be solved in this technical field. Summary of the Invention
[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention solves the problem of inconsistent calibration methods for different models of coherent optical modules.
[0006] The embodiments of the present invention adopt the following technical solutions:
[0007] For the transmitter of the coherent optical module, the transmitter responsivity of each channel at different wavelengths and temperatures is obtained based on the probe photocurrent. The target sampling value of the probe photocurrent is calculated based on the transmitter responsivity corresponding to the current wavelength and temperature and the target output power. The output parameters are adjusted to make the actual sampling value of the transmitter probe photocurrent close to the target sampling value. For the receiver of the coherent optical module, the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures is obtained based on the probe photocurrent of different polarization states. The input power is calculated based on the receiver responsivity corresponding to the current wavelength and temperature and the probe photocurrent of each polarization state. The receiving parameters are adjusted to make the calculated input power close to the actual input power.
[0008] Preferably, the step of obtaining the transmitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent specifically includes: setting the automatic bias current control function of the coherent optical module to a locked state, turning off the frequency signals of all channels, and reading the probe photocurrent of each channel in the no-light state; sequentially turning on the frequency signal of each channel, reading the probe photocurrent of each channel in the light-emitting state respectively, and obtaining the corresponding output power, and calculating the transmitter responsivity of each channel of the transmitter based on the probe photocurrent in the no-light state, the probe photocurrent in the light-emitting state, and the output power.
[0009] Preferably, the step of obtaining the transmitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent further includes: obtaining the transmitter responsivity of each channel at multiple temperatures and multiple wavelengths, and recording the transmitter responsivity corresponding to each set of temperatures and wavelengths to facilitate obtaining the transmitter responsivity corresponding to the current wavelength and temperature.
[0010] Preferably, adjusting the light output parameters to make the actual sampled value of the probe photocurrent at the transmitter close to the target sampled value specifically includes: calculating the target sampled value of the probe photocurrent for each channel based on the target light output power, and adjusting the drive gain for each channel so that the difference between the actual sampled value of the probe photocurrent for that channel and the target sampled value for that channel is less than a preset current error, thereby making the difference between the actual light output power value at the transmitter and the target light output power less than a preset power error.
[0011] Preferably, the step of obtaining the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states specifically includes: preventing the input port of the receiver from receiving incident light and reading the probe photocurrent in the dark state; allowing the input port of the receiver to receive incident light and obtaining the probe photocurrent corresponding to each polarization state when there is light; and calculating the receiver responsivity of each polarization state based on the probe photocurrent in the dark state and the probe photocurrent of each polarization state.
[0012] Preferably, the step of obtaining the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states specifically includes: obtaining the receiver responsivity at multiple temperatures and multiple wavelengths for each polarization state, and recording the receiver responsivity corresponding to each set of temperatures and wavelengths to facilitate obtaining the receiver responsivity corresponding to the current wavelength and temperature.
[0013] Preferably, the step of calculating the incident light power based on the receiver responsivity at the current wavelength and temperature and the probe photocurrent for each polarization state specifically includes: under normal operating conditions of the coherent optical module, reading the X-polarization state probe photocurrent and Y-polarization state probe photocurrent at the receiver, calculating the incident light power component for each polarization state based on the responsivity and probe photocurrent at the current wavelength and temperature, and calculating the incident light power at the receiver based on the X-polarization state incident light power component and the Y-polarization state incident light power component.
[0014] On the other hand, the present invention provides a calibration device for a coherent optical module based on photocurrent detection, specifically comprising: a transmit power measuring device, a test light source, an amplifying device, a filtering device, a beam splitter, and a receive power measuring device. Specifically: the transmit power measuring device is used to connect to the transmitting end of the coherent optical module; the test light source, the filtering device, and the amplifying device are connected in sequence; the amplifying device is connected to the input port of the beam splitter; one output port of the beam splitter is used to connect to the receiving end of the coherent optical module; and the other output port of the beam splitter is connected to the receive power measuring device. The transmit power measuring device is used to obtain the actual output power required in any of the first aspects, so as to compare the actual output power with the target output power to complete the calibration of the transmitting end; the receive power measuring device is used to obtain the incident light power at the receiving end, so as to compare the actual incident light power with the calculated incident light power to complete the calibration of the receiving end.
[0015] Preferably, the filtering device includes an optical switch and a wavelength division multiplexer. Specifically, the test light source is connected to the optical switch, the optical switch is connected to the wavelength division multiplexer, and the wavelength division multiplexer is connected to the amplification device, for filtering the output light of the test light source.
[0016] Preferably, the amplification device includes an optical amplifier and a variable optical attenuator. Specifically, the filter device is connected to the optical amplifier, the optical amplifier is connected to the variable optical attenuator, and the visible light attenuator is connected to the input port of the beam splitter, for adjusting the output optical power of the test light source.
[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: The responsivity of the transmitter and receiver under different parameters is obtained based on the probe photocurrent; the output power of the transmitter is adjusted based on the transmitter's responsivity; and the output power of the receiver is calculated based on the receiver's responsivity. The method provided by this invention, based on the actual responsivity under different parameters, completes the calibration calculation of the coherent optical module, enabling the calibration of different types of coherent optical modules and improving calibration efficiency and accuracy. Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0019] Figure 1 A flowchart illustrating a calibration method for a coherent optical module based on photocurrent detection, provided in an embodiment of the present invention;
[0020] Figure 2 To represent the intent of the transmitter's response data in a specific real-world scenario;
[0021] Figure 3 To represent the intent of the receiver's response data in a specific real-world scenario;
[0022] Figure 4 A schematic diagram of a calibration device for a coherent optical module based on photocurrent detection, provided in an embodiment of the present invention;
[0023] Figure 5 A schematic diagram of the filter device structure in a calibration device for a coherent optical module based on photocurrent detection, provided in an embodiment of the present invention;
[0024] Figure 6 A schematic diagram of the amplification device structure in a calibration device for a coherent optical module based on photocurrent detection, provided in an embodiment of the present invention;
[0025] Figure 7 This is a schematic diagram of another calibration device for a coherent optical module based on photocurrent detection, provided in an embodiment of the present invention. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0027] This invention is an architecture of a specific functional system. Therefore, the specific embodiments mainly describe the functional logic relationship of each structural module, and do not limit the specific software and hardware implementation methods.
[0028] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0029] Example 1:
[0030] To enable the reporting of output optical power at the transmitter and input optical power at the receiver of different coherent optical modules, and to improve the accuracy and calibration efficiency of coherent optical modules across the entire power range, this embodiment provides a calibration method for coherent optical modules based on Monitor Photo Diode (MPD). By calibrating the relationship between the effective current sampling values of the MPD at the transmitter and receiver and the optical power, the output optical power of the coherent module is adjusted, and the input optical power of the coherent module is monitored.
[0031] like Figure 1 As shown, the specific steps of the method provided in this embodiment of the invention are as follows:
[0032] Step 101: For the transmitter of the coherent optical module, obtain the transmitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent. Calculate the target sampling value of the probe photocurrent based on the transmitter responsivity corresponding to the current wavelength and temperature and the target output power. Adjust the output parameters to make the actual sampling value of the transmitter probe photocurrent close to the target sampling value.
[0033] Since coherent optical modules have different responsivity to different wavelengths of optical signals and different temperatures of devices such as COSA, when calibrating the transmitter (Tx), the sampled values of the MPD probe photocurrent noise floor of each channel at different wavelengths and different device temperatures, the sampled values of the MPD digital signal when the transmitter is emitting light, and the actual output power of the transmitter are obtained in order to obtain the MPD-based transmitter responsivity corresponding to each combination of parameters of each channel.
[0034] Then, based on the current wavelength and current device temperature, the responsivity under the current state is obtained. Based on the responsivity and the target output power, the target sampling value of the transmitter's probe photocurrent under the current state is calculated. By adjusting the output light, the actual sampling value of the transmitter's probe photocurrent is made close to the target sampling value, thereby making the actual output power close to the target output power, thus completing the calibration of the transmitter.
[0035] Step 102: For the receiver of the coherent optical module, obtain the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states. Calculate the incident light power based on the receiver responsivity corresponding to the current wavelength and temperature, as well as the probe photocurrent of each polarization state. Adjust the receiving parameters to make the calculated incident light power close to the actual incident light power.
[0036] When performing receiver (Rx) calibration, the MPD probe photocurrent noise floor of a specific incident light X polarization state and Y polarization state at different wavelengths and temperatures is obtained, as well as the MPD digital signal sampling value when there is incident light, to obtain the MPD-based receiver responsivity of the X polarization state and Y polarization state under various parameter combinations.
[0037] Then, based on the current wavelength and current device temperature, the responsivity under the current state is obtained. Based on the receiver responsivity corresponding to the X polarization state and the Y polarization state, as well as the current probe photocurrent sampling values of the current X polarization state and the Y polarization state, the incident light power is calculated and compared with the actual incident light power to complete the calibration of the receiver.
[0038] After steps 101-102 provided in this embodiment, the responsivity of the transmitter and receiver can be obtained by detecting the photocurrent value through MPD, and the calibration of the transmitter and receiver can be completed based on the responsivity.
[0039] When obtaining the transmitter responsivity, each channel needs to be controlled individually. The transmitter responsivity of each channel at different wavelengths and temperatures is obtained based on the probe photocurrent. Since MPD dark current or hardware noise introduces MPD probe photocurrent noise floor (i.e., the probe photocurrent in the absence of light), all cases involving MPD probe photocurrent sampling and calculation require obtaining the MPD probe photocurrent noise floor first. The automatic bias current control function of the coherent optical module is set to locked, all channel frequency signals are turned off, and the probe photocurrent of each channel in the absence of light is read. After obtaining the MPD probe photocurrent noise floor, the frequency signals of each channel are turned on sequentially, and the probe photocurrent in the output state of each channel is read, along with the corresponding output power. The transmitter responsivity of each channel is calculated based on the probe photocurrent in the absence of light, the probe photocurrent in the output state, and the output power. In specific implementation scenarios, the wavelength and temperature sampling points for probe photocurrent sampling can be set according to actual needs, ensuring coverage of all operating states of the coherent optical module and guaranteeing the required calculation accuracy.
[0040] In a practical scenario, when obtaining the transmitter responsivity, based on preliminary evaluation results, eight temperature sampling points (10℃, 25℃, 35℃, 45℃, 55℃, 65℃, 75℃, and 85℃) and nine wavelength sampling points (191.3GHz, 191.9GHz, 192.5GHz, 193.1GHz, 193.7GHz, 194.3GHz, 194.9GHz, 195.5GHz, and 196.1GHz) are tentatively selected. The coherent optical module transmitter has four MPD channels (XI, XQ, YI, and YQ), denoted as MPD_TX, MPD_TQ, MPD_YI, and MPD_YQ respectively, and each channel needs to be calibrated separately. Taking MPD_TX as an example, the automatic bias control (ABC) function of the module is in a normal locked state. First, the digital frequency signals (DSP RF) of all channels XI / XQ / YI / YQ are turned off, and the probe photocurrent (i.e., dark current) sampling value in the no-light state of MPD_XI is read and recorded as ADC_MPD_XI_no light. Then, the three DSP RF signals of XQ / YI / YQ are turned off, and only the DSP RF signal of XI is turned on. The probe photocurrent sampling value in the light-emitting state of MPD_XI is read and recorded as ADC_MPD_XI. In actual implementation, the DSP RF signal of each channel can be turned on one by one; for ease of calculation, the DSP RF signal of only one channel can be turned on in turn, while the DSP RF signals of the other three channels are turned off.
[0041] The transmit responsivity Res_MPD_XI of each channel can be calculated based on the actual output power XI_Pwr at the transmitter of the coherent optical module. The specific formula is as follows:
[0042]
[0043] The unit of XI_Pwr is dBm, and the unit of Res_MPD_XI is ADC / mW.
[0044] To facilitate subsequent calculations of the transmitter responsivity corresponding to the current wavelength and temperature, when obtaining the transmitter responsivity of each channel at different wavelengths and temperatures, the transmitter responsivity of each channel at multiple temperatures and multiple wavelengths can be obtained separately. The responsivity corresponding to each set of temperature and wavelength can be recorded to generate a transmitter responsivity data table. For example, in the scenario described above where calibration is performed at 8 temperatures and 9 wavelengths, after full-temperature, full-wavelength calibration, each MPD channel will have... Figure 2 The table shown contains 9*8=72 transmitter responsivity data points. Figure 2 Only a portion of the data is shown here. In subsequent use, you can directly look up the table to obtain the transmitter responsivity corresponding to different temperatures and wavelengths, or you can interpolate from the transmitter responsivity data table to obtain the transmitter responsivity that is not at the sampling point location but is included within the sampling range. In practical implementation, you can choose an appropriate interpolation method according to the specific situation. For example, when the measured responsivity does not change regularly with temperature and wavelength, two-dimensional linear interpolation can be used, that is, using the responsivity data from the two adjacent temperature sampling points and the two adjacent wavelength sampling points, for a total of four data points, to perform two-dimensional linear interpolation.
[0045] After obtaining the transmitter responsivity of each MPD channel, the output parameters can be adjusted to bring the transmitter power close to the target output power for calibration. In practice, the selection and adjustment method of the output parameters are determined based on the specific type and control method of the coherent optical module. For example, the target sampled value of the probe photocurrent for each channel is calculated based on the target output power. For each channel, the drive gain is adjusted so that the difference between the actual sampled value of the probe photocurrent and the target sampled value is less than a preset current error, thus ensuring that the difference between the actual output power and the target output power is less than the preset power error. Specifically, the output power of the corresponding channel is changed by adjusting the gain amplitude from the DSP to the driver, bringing the actual output power of the transmitter closer to the target output power. In practice, the gain from the DSP to the driver has four channels, and the gain of each channel can be adjusted separately.
[0046] In a practical scenario, taking the XI channel as an example, when the target output power of the coherent optical module is Tx_Pwr (dBm), the responsivity Res_MPD_XI under the current state is obtained by interpolation from the transmitter responsivity data table corresponding to the XI channel, based on the current wavelength and the current device temperature. Then, the target sampling value ADC_Tx_MPD_XI_Target of the MPD_XI channel under the current state is calculated based on the target output power. The specific formula is as follows:
[0047] ADC_Tx_MPD_XI_Target=Res_MPD_XI*10^(10^XI_Pwr / 10).
[0048] After obtaining the target sample value, the drive gain Driver_GC_XI of the XI channel is adjusted so that the probe photocurrent sample value of the XI channel is close to ADC_Tx_MPD_XI_Target, and finally the output power of the XI channel is close to the target output power.
[0049] When obtaining the receiver responsivity, it is necessary to acquire the probe photocurrent corresponding to each polarization state separately, and then obtain the receiver responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent. First, it is also necessary to acquire the MPD photocurrent floor. The tuning function of the coherent optical module is turned off, so that the input port of the receiver does not receive incident light, and the probe photocurrent in the dark state is read. After acquiring the MPD probe photocurrent floor, the tuning function of the receiver is then turned on, so that the input port of the receiver receives incident light, and the probe photocurrent corresponding to each polarization state is acquired when there is light. The receiver responsivity of each polarization state is calculated based on the photocurrent in the dark state and the probe photocurrent of each polarization state. In specific implementation scenarios, the wavelength and temperature sampling points for probe photocurrent sampling can be set according to actual needs, as long as they can cover all operating states of the coherent optical module and ensure the required calculation accuracy.
[0050] In a practical scenario, when obtaining the receiver responsivity, the two probe photocurrent responsivityes corresponding to the X-polarization and Y-polarization states are calibrated separately. The signal light input from the receiver's input port contains X-polarization and Y-polarization components, denoted as Rx_MPD_X and Rx_MPD_Y, respectively. The sum of the power components corresponding to Rx_MPD_X and Rx_MPD_Y represents the total power of the input light, which can be used for reporting the optical power of Rx. First, all power supplies to the coherent optical module are turned on, and the tuning function of the coherent optical module (Integrated Tunable Laser Assembly, abbreviated as ITLA) is turned off, so that the Rx port does not receive the input light signal. The MPD probe photocurrent at this time is read and denoted as MPD_no light. MPD_no light can be decomposed into MPD_X_no light corresponding to the X-polarization component and MPD_Y_no light corresponding to the Y-polarization component. Next, obtain the incident optical power value RX_Power_dBm at the receiver, and obtain the X-polarization state probe photocurrent RX_MPD_X_I corresponding to RX_MPD_X, and the Y-polarization state probe photocurrent RX_MPD_Y_I corresponding to RX_MPD_Y, and calculate the responsivity. The specific formula is as follows:
[0051] RX_Power_mW=10^(RX_Power_dBm / 10);
[0052]
[0053]
[0054] Wherein, RX_Power_mW is an intermediate variable used for unit conversion, Res_RX_MPD_X is the receiver responsivity in the X polarization state, and Res_RX_MPD_Y is the receiver responsivity in the Y polarization state.
[0055] To facilitate subsequent calculations of the receiver responsivity corresponding to the current wavelength and temperature, when obtaining the receiver responsivity for each polarization state at different wavelengths and temperatures, the transmitter responsivity for each polarization state at multiple temperatures and multiple wavelengths can be obtained separately. The responsivity for each set of temperature and wavelength is recorded to facilitate obtaining the transmitter responsivity corresponding to the current wavelength and temperature. For example, in the scenario described above, where calibration is performed at 8 temperatures and 9 wavelengths, and the receiver power is set to approximately -12dBm, after full-temperature, full-wavelength calibration, each polarization state will have a responsivity as shown below. Figure 3 The response rate data table shown contains 9*8=72 receiver response rate data points. Figure 3 Only a portion of the data is shown here. In subsequent use, you can directly look up the table to obtain the receiver responsivity corresponding to different temperatures and wavelengths, or you can interpolate from the receiver responsivity data table to obtain the receiver responsivity at locations not at the sampling points but included within the sampling range.
[0056] After obtaining the receiver responsivity, the received incident light power can be calculated based on the receiver responsivity at the current wavelength and temperature, as well as the sampled value for each polarization state. Calibration is then performed based on the calculated incident light power and the actual incident light power. Under normal operating conditions, the coherent optical module reads the X-polarization state probe photocurrent and Y-polarization state probe photocurrent at the receiver. Based on the responsivity and probe photocurrent for each polarization state at the current wavelength and temperature, the incident light power component for the corresponding polarization state is calculated. The incident light power at the receiver is then calculated based on the X-polarization state incident light power component and the Y-polarization state incident light power component. In other words, the incident light power component for the X-polarization state is calculated based on the X-polarization state responsivity and X-polarization state probe photocurrent at the current wavelength and temperature; the incident light power component for the Y-polarization state is calculated based on the Y-polarization state responsivity and Y-polarization state probe photocurrent at the current wavelength and temperature; and the incident light power at the receiver is then calculated based on the X-polarization state incident light power component and the Y-polarization state incident light power component.
[0057] In a real-world scenario, under normal operating conditions, the module reads the probe photocurrent RX_MPD_X_I of the X-polarized optical component Rx_MPD_X and the probe photocurrent RX_MPD_Y_I of the Y-polarized optical component Rx_MPD_Y. It then interpolates to obtain the receiver responsivity RES_RX_MPD_X and RES_RX_MPD_Y of the X-polarized and Y-polarized states at the current wavelength and temperature. Finally, it calculates the X-polarized optical power component RX_Power_X and the Y-polarized optical power polarization component RX_Power_Y after VOA attenuation. The specific calculation formulas are as follows:
[0058]
[0059]
[0060] Finally, by summing the power components of all polarization states, the total optical power at the RX input is calculated:
[0061] RX_Power=RX_Power_X+RX_Power_Y.
[0062] Here, RX_Power is the calculated incident optical power, which should theoretically match the actual incident optical power. If the calculated incident optical power does not match the actual incident optical power, the calibration parameters need to be adjusted to complete the calibration.
[0063] The calibration method for coherent optical modules based on photocurrent detection provided in this embodiment calculates the responsivity of the transmitter and receiver of the coherent optical module by using the photocurrent detection that is present in different coherent optical modules. Then, the responsivity is combined with the actual output and input optical power to adjust the calibration parameters, thereby meeting the needs of rapid calibration of different types of coherent optical modules, improving calibration efficiency, and improving the control accuracy and reporting accuracy of the coherent optical module throughout the entire power range.
[0064] Example 2:
[0065] Based on the calibration method for coherent optical modules based on photocurrent detection provided in Embodiment 1 above, this invention also provides a calibration device for coherent optical modules based on photocurrent detection that can be used to implement the above method. Based on the method in Embodiment 1, the device provided in this embodiment can perform calibration of both the transmitter and receiver ends of a coherent optical module.
[0066] like Figure 4 The diagram shown is a schematic of the device architecture in an embodiment. The calibration device includes a transmit power measuring device, a test light source, an amplifying device, a filtering device, a beam splitter, and a receive power measuring device. Specifically: the transmit power measuring device is connected to the transmitting end of the coherent optical module; the test light source, the filtering device, and the amplifying device are connected in sequence; the amplifying device is connected to the input port of the beam splitter; one output port of the beam splitter is connected to the receiving end of the coherent optical module; and the other output port of the beam splitter is connected to the receive power measuring device.
[0067] After connecting the corresponding ports of the coherent optical module to the device provided in this embodiment according to the above-described link, the coherent optical module can be calibrated. The transmit power measuring device is used to obtain the actual output optical power of the coherent optical module transmitter required in Embodiment 1, so as to compare the actual output optical power with the target output optical power and complete the calibration of the transmitter. The receive power measuring device is used to obtain the actual input optical power of the coherent optical module receiver required in Embodiment 1, so as to compare the actual input optical power with the calculated input optical power and complete the calibration of the receiver. In specific implementations, the transmit power measuring device and the receive power measuring device can be optical power meters, photoresistors, or other measuring devices capable of acquiring optical power.
[0068] like Figure 5 As shown, the filtering device includes an optical switch and a wavelength division multiplexer. Specifically, the test light source is connected to the optical switch, the optical switch is connected to the wavelength division multiplexer, and the wavelength division multiplexer is connected to the amplification device, which is used to filter the output light of the test light source.
[0069] like Figure 6 As shown, the amplification device includes an optical amplifier and a variable optical attenuator. Specifically, the filter device is connected to the optical amplifier, the optical amplifier is connected to the variable optical attenuator, and the visible light attenuator is connected to the input port of the beam splitter, which is used to adjust the output optical power of the test light source.
[0070] In a specific scenario, based on the transmitter and receiver calibration method provided in Embodiment 1, the equipment provided in this embodiment is used to build a system as follows: Figure 7 The calibration environment is as follows: At the transmitting end, a power meter is used as the transmit power measurement device. The power meter is directly connected to the coherent optical module's transmitting end and is used to measure the actual output optical power of each channel at the transmitting end. The transmitter calibration is completed by comparing the actual output optical power with the target output optical power. At the receiving end, an amplified spontaneous emission (ASE) light source is used as the test light source. A 1*9 optical switch and a 48-wavelength demultiplexer are used as filtering devices to output test light of different wavelengths. Optical amplifiers (OA) and variable optical attenuators (VOA) are used as amplification devices. The test light is amplified by the OA and then attenuated by the VOA to adjust the output power. The filtered and amplified test light finally enters the beam splitter and is split into two optical signals, which are input to the coherent optical module's receiving end and another power meter, which serves as the receive power measurement device, respectively. The receiver calibration is completed by comparing the actual input optical power with the calculated input optical power. As can be seen from the implementation process in the above-described real-world scenario, the device provided in this embodiment can complete the calibration of the coherent optical module transmitter and receiver based on the method provided in Embodiment 1.
[0071] In an optional embodiment, the calibration device further includes a controller, which is used to acquire the transmitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent, calculate the target sampling value of the corresponding probe photocurrent based on the transmitter responsivity corresponding to the current wavelength and temperature and the target output power, and trigger the adjustment of the output parameters of the coherent optical module to make the actual sampling value of the transmitter probe photocurrent close to the target sampling value; the controller is also used to acquire the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states, calculate the input power based on the corresponding receiver responsivity and the probe photocurrent of each polarization state, and trigger the adjustment of the receiver parameters of the coherent optical module to make the calculated input power close to the actual input power.
[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A calibration method for a coherent optical module based on photocurrent detection, characterized in that, Specifically, it includes: For the transmitter of the coherent optical module, the transmitter responsivity of each channel at different wavelengths and temperatures is obtained based on the probe photocurrent detected by the MPD. The target sampling value of the probe photocurrent is calculated based on the transmitter responsivity corresponding to the current wavelength and temperature and the target output power. The output parameters are adjusted so that the actual sampling value of the transmitter probe photocurrent is close to the target sampling value. For the receiver of the coherent optical module, the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures is obtained based on the probe photocurrent of different polarization states. The input light power is calculated based on the receiver responsivity corresponding to the current wavelength and temperature and the probe photocurrent of each polarization state. The receiving parameters are adjusted to make the calculated input light power close to the actual input light power.
2. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The process of obtaining the emitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent specifically includes: Set the automatic bias current control function of the coherent optical module to the locked state, turn off the frequency signals of all channels, and read the probe photocurrent of each channel in the dark state. The frequency signal of each channel is turned on in sequence, the probe photocurrent in the light output state of each channel is read, and the corresponding output power is obtained. The transmitter responsivity of each channel of the transmitter is calculated based on the probe photocurrent in the no-light state, the probe photocurrent in the light output state, and the output power.
3. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The method of obtaining the emitter responsivity of each channel at different wavelengths and temperatures based on the probe photocurrent also includes: The transmitter responsivity of each channel at multiple temperatures and multiple wavelengths is obtained separately. The transmitter responsivity corresponding to each set of temperature and wavelength is recorded to facilitate the acquisition of the transmitter responsivity corresponding to the current wavelength and temperature.
4. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The adjustment of the light output parameters to make the actual sampled value of the photocurrent detected at the transmitting end close to the target sampled value specifically includes: Calculate the target sampling value of the probe photocurrent for each channel based on the target output power. Adjust the drive gain for each channel so that the difference between the actual sampling value of the probe photocurrent for that channel and the target sampling value for that channel is less than the preset current error, thereby making the difference between the actual output power value of the transmitter and the target output power less than the preset power error.
5. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The method of obtaining the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states specifically includes: The input port of the receiver is prevented from receiving incident light, and the probe photocurrent in the dark state is read. The receiver's input port receives incident light, and the probe photocurrent corresponding to each polarization state is obtained when there is light. The receiver responsivity for each polarization state is calculated based on the probe photocurrent in the dark state and the probe photocurrent for each polarization state.
6. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The method of obtaining the receiver responsivity corresponding to each polarization state at different wavelengths and temperatures based on the probe photocurrent of different polarization states specifically includes: The receiver responsivity for each polarization state at multiple temperatures and multiple wavelengths is obtained separately. The receiver responsivity corresponding to each set of temperature and wavelength is recorded to facilitate the acquisition of the receiver responsivity corresponding to the current wavelength and temperature.
7. The calibration method for a coherent optical module based on photocurrent detection according to claim 1, characterized in that, The calculation of input optical power based on the receiver responsivity corresponding to the current wavelength and temperature, and the probe photocurrent for each polarization state, specifically includes: Under normal operating conditions, the coherent optical module reads the X-polarization state probe photocurrent and Y-polarization state probe photocurrent at the receiver. Based on the responsivity and probe photocurrent of each polarization state at the current wavelength and temperature, it calculates the incident light power component under the corresponding polarization state. Based on the incident light power component of the X-polarization state and the incident light power component of the Y-polarization state, it calculates the incident light power at the receiver.
8. A calibration apparatus for a coherent optical module based on photocurrent detection for implementing the calibration method described in any one of 1-7, characterized in that, This includes transmit power measurement devices, test light sources, amplification devices, filtering devices, beam splitters, and receive power measurement devices, specifically: The transmit power measuring device is used to connect to the transmitting end of the coherent optical module. The test light source, filter device and amplifier device are connected in sequence. The amplifier device is connected to the input port of the beam splitter. One output port of the beam splitter is used to connect to the receiving end of the coherent optical module. The other output port of the beam splitter is connected to the receive power measuring device. Among them, the transmit power measurement device is used to obtain the actual output power corresponding to the actual sampled value, so as to compare the actual output power with the target output power and complete the calibration of the transmitter. The receiver power measurement device is used to obtain the incident optical power at the receiver so that the actual incident optical power can be compared with the calculated incident optical power to complete the calibration of the receiver.
9. The calibration device for a coherent optical module based on photocurrent detection according to claim 8, characterized in that, The filtering device includes an optical switch and a wavelength division multiplexer, specifically: The test light source is connected to the optical switch, the optical switch is connected to the wavelength division multiplexer, and the wavelength division multiplexer is connected to the amplification device to filter the output light of the test light source.
10. The calibration device for a coherent optical module based on photocurrent detection according to claim 8, characterized in that, The amplification device includes an optical amplifier and a variable optical attenuator, specifically: The filter is connected to the optical amplifier, the optical amplifier is connected to the variable optical attenuator, and the visible light attenuator is connected to the input port of the beam splitter, which is used to adjust the output optical power of the test light source.