Self-referencing analog control loop for photonic device parameter stabilization

Abstract

The application discloses a self-reference analog control loop for parameter stability of a photonic device, comprising a reference value generating circuit and a photonic device analog control loop; the photonic device analog control loop comprises a photonic device, a monitoring unit, an analog front end, an analog control core circuit, an output stage and an actuator connected in sequence; the reference value generating circuit is connected with the analog front end and the analog control core circuit; the reference value generating circuit comprises a comparator, a digital finite state machine and a digital-to-analog conversion module, and generates a reference value signal and a switch control signal according to a processed electric signal output by the analog front end; the analog control core circuit comprises an operational amplifier and a switch, and generates an analog control signal according to the processed electric signal, the reference value signal and the switch control signal; the output stage generates a driving signal according to the analog control signal, and the actuator adjusts an optical parameter of the photonic device according to the driving signal. High-precision, fast and low-power photonic device parameter stability control is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optoelectronic chip design, and more particularly, relates to a self-reference analog control loop for stabilizing parameters of a photonic device. BACKGROUND

[0002] On-chip photonic devices have advantages such as small area, small transmission loss, and low cost, and are widely used in the fields of optical communication, optical detection, and optical computing. In order to prevent the optical parameters of the photonic device from changing due to temperature changes, manufacturing deviations, and input light changes, a closed-loop feedback control system is usually introduced to detect and control the optical parameters. The closed-loop feedback control system is mostly composed of a photonic device, a monitoring unit, a control algorithm unit, and a tuning unit. The working principle is that the monitoring unit detects the optical parameters of the photonic device, the control algorithm unit calculates a suitable output value for the tuning unit according to a suitable control algorithm, and the tuning unit adjusts the optical parameters of the photonic device.

[0003] The control algorithm unit is mostly an algorithm based on digital circuit design, which can be roughly divided into a maximum / minimum value locking algorithm and a reference value locking algorithm. The maximum / minimum value locking algorithm, also known as the hill climbing algorithm, is suitable for application scenarios that need to lock to a local maximum / minimum value point. The working principle is that, in combination with the physical quantity representing the optical parameters detected by the monitoring unit, the current state is judged according to the change of the physical quantity and the change of the output value at the last moment, so that the next moment is judged and a suitable output value is obtained, thereby realizing maximum / minimum value locking. The maximum / minimum value locking algorithm can effectively compensate for the changes in optical parameters caused by process deviations, thermal fluctuations, and input laser changes, and also consumes less hardware resources, so it is widely used in the closed-loop feedback control system of the optical parameters of the photonic device. The working principle of the reference value locking algorithm is that, according to the difference between the physical quantity representing the optical parameters detected by the monitoring unit and the reference value set manually or automatically, a suitable output value is calculated for the tuning unit, and finally the reference value is locked. Although the reference value locking algorithm is easy to implement in hardware, it is necessary to ensure the reliability of the reference value set manually or automatically, otherwise it will cause the deviation of the final locking point. For example, without additional auxiliary modules, the input laser power fluctuation will cause the physical quantity detected by the monitoring unit to change, but the resonant wavelength of the micro-ring resonator and other optical parameters will not change dramatically with the input light power, thus causing the deviation of the locking point.

[0004] The algorithm based on digital circuit design often needs to convert the analog signal to digital signal and convert the digital signal generated by the algorithm to analog signal again. The analog-to-digital conversion and digital-to-analog conversion process will cause the generation of quantization error, which will reduce the final locking accuracy, and will also cause greater power consumption and chip area, which is not suitable for large-scale and low-power applications. SUMMARY

[0005] In view of the defects of the related art, the present application aims to provide a self-reference analog control loop for parameter stabilization of a photonic device, which aims to solve the problem that in the existing closed-loop feedback control system, the control signal for controlling the optical parameter is generated by a digital circuit, and the quantization error is generated in the analog-digital conversion and digital-analog conversion processes, which reduces the final locking precision and increases the power consumption and chip area.

[0006] To achieve the above-mentioned purpose, in a first aspect, the present application provides a self-reference analog control loop for parameter stabilization of a photonic device, comprising a reference value generation circuit and a photonic device analog control loop.

[0007] The photonic device analog control loop comprises a photonic device, a monitoring unit, an analog front end, an analog control core circuit, an output stage and an actuator connected in sequence; the reference value generation circuit is connected with the analog front end and the analog control core circuit.

[0008] The monitoring unit is configured to obtain the optical signal of the photonic device and generate an initial electrical signal.

[0009] The analog front end is configured to process the initial electrical signal and output a processed electrical signal.

[0010] The reference value generation circuit comprises a comparator, a digital finite state machine and a digital-to-analog conversion module; the comparator compares the processed electrical signal with the reference value signal generated by the digital-to-analog conversion module to generate a comparison result; the digital finite state machine generates a switch control signal and a digital reference value for controlling the analog control core circuit according to the comparison result; and the digital-to-analog conversion module generates a reference value signal according to the digital reference value.

[0011] The analog control core circuit comprises an operational amplifier and a switch; the processed electrical signal and the reference value signal are calculated by the operational amplifier to generate the analog control signal; and the switch control signal is used to control the state of the switch, so that the switch selects the processed electrical signal and the reference value signal to input the same-phase input terminal or the inverse-phase input terminal of the operational amplifier.

[0012] The output stage is configured to generate a driving signal according to the analog control signal and output the driving signal to the actuator.

[0013] The actuator is configured to generate an execution signal according to the driving signal, and adjust the optical parameter of the photonic device according to the execution signal.

[0014] Optionally, the analog control core circuit comprises a first operational amplifier, a second operational amplifier and a first switch.

[0015] The non-inverting input terminal of the first operational amplifier and the inverting input terminal of the second operational amplifier both receive the processed electrical signal, and the inverting input terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier both receive the reference value signal;

[0016] The output terminal of the first operational amplifier and the output terminal of the second operational amplifier form a single-pole double-throw switch with the first switch, which is switched according to the switch control signal; when the first switch is connected to the output terminal of the first operational amplifier, the analog control core circuit outputs an analog control signal obtained by differentiating the processed electrical signal and the reference value signal; when the first switch is connected to the output terminal of the second operational amplifier, the analog control core circuit outputs an analog control signal obtained by differentiating the reference value signal and the processed electrical signal.

[0017] Optionally, the analog control core circuit comprises a third operational amplifier and a first switch.

[0018] The first switch is a combination switch, which is used to select to connect the processed electrical signal and the reference value signal to the non-inverting input terminal and the inverting input terminal of the third operational amplifier respectively, or to connect the processed electrical signal and the reference value signal to the inverting input terminal and the non-inverting input terminal of the third operational amplifier respectively.

[0019] Optionally, the analog control core circuit further comprises a second switch, a third switch and a buffer stage.

[0020] The second switch is connected to a power supply, the third switch is grounded, and the second switch and the third switch are connected in series; the input terminal of the buffer stage is connected to the output terminal of the operational amplifier, and the output terminal of the buffer stage serves as the output terminal of the analog control core circuit.

[0021] When the second switch is closed, the analog control signal output by the operational amplifier is set to the voltage of the power supply.

[0022] When the third switch is closed, the analog control signal output by the operational amplifier is set to zero voltage.

[0023] The buffer stage is an amplifier, which is used to amplify the analog control signal.

[0024] Optionally, the implementation process of the reference value generating circuit for generating the reference value signal and the switch control signal comprises:

[0025] The digital finite state machine initializes an upper reference register and a lower reference register, a value of the upper reference register and a value of the lower reference register differ by a fixed value, and a digital-to-analog conversion output signal corresponding to the lower reference register is less than the current processed electrical signal;

[0026] The comparator compares the processed electrical signal with the digital-to-analog conversion output signal corresponding to the lower reference register to obtain a comparison result.

[0027] When the comparison result is greater than, the digital finite state machine synchronously increments the value of the upper reference register and the value of the lower reference register; when the comparison result is less than, the digital finite state machine synchronously decrements the value of the upper reference register and the value of the lower reference register, and when the comparison result of the previous moment is greater than, the switch control signal is inverted.

[0028] Optionally, the actuator is an integrated heater or a PN junction.

[0029] The integrated heater adjusts an optical parameter of the photonic device through a thermo-optic effect.

[0030] The PN junction adjusts the optical parameter of the photonic device through an electro-optic effect.

[0031] Optionally, the photonic device is a ring resonator, a ring modulator, or a Mach-Zehnder modulator.

[0032] Optionally, the photonic device analog control loop is n, when n is greater than or equal to 2, the self-reference analog control loop further comprises an analog front-end output multiplexer, a reference value signal demultiplexer, and a switch control signal demultiplexer.

[0033] The analog front-ends of the n photonic device analog control loops are connected to the analog front-end output multiplexer, and the analog control core circuits are connected to the reference value signal demultiplexer and the switch control signal demultiplexer.

[0034] The reference value generation circuit is configured to sequentially receive the processed electrical signals of the n photonic device analog control loops, and output a switch control signal and a reference value signal.

[0035] In a second aspect, the present application further provides a control method of a self-reference analog control loop for photonic device parameter stability, which is suitable for the self-reference analog control loop for photonic device parameter stability as described in any one of the first aspect, and comprises:

[0036] The monitoring unit obtains an optical signal of the photonic device and generates an initial electrical signal.

[0037] Analog front end processes the initial electrical signal to output a processed electrical signal;

[0038] The reference value generation circuit generates a reference value signal and a switch control signal according to the processed electrical signal and outputs them to the analog control core circuit;

[0039] The analog control core circuit generates an analog control signal according to the processed electrical signal, the reference value signal and the switch control signal and outputs it to the output stage;

[0040] The output stage generates a driving signal according to the analog control signal and outputs it to the actuator;

[0041] The actuator generates an execution signal according to the driving signal and adjusts the optical parameter of the photonic device according to the execution signal.

[0042] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0043] 1. The self-reference analog control loop for photonic device parameter stability provided by the present application has the advantages of simple structure and easy on-chip implementation. The analog control core circuit is composed of only an operational amplifier and a switch, and the reference value generation circuit is composed of a comparator, a finite state machine and a digital-to-analog conversion module, which consumes very few hardware resources, thereby overcoming the disadvantages of complex structure and difficulty in large-scale integration of traditional closed-loop control methods based on digital control algorithms.

[0044] 2. In the self-reference analog control loop for photonic device parameter stability provided by the present application, only digital circuits are used as the reference value generation circuit, so the frequency of the digital circuits does not affect the control speed of the analog control loop, thereby breaking away from the limitation of clock frequency on performance and overcoming the bottleneck problem caused by clock frequency in traditional control methods.

[0045] 3. The self-reference analog control loop for photonic device parameter stability provided by the present application can automatically update the reference value and the switch control signal through the finite state machine, thereby avoiding the problem of manually setting the reference value in traditional methods.

[0046] 4. The self-reference analog control loop for photonic device parameter stability provided by the present application can realize effective control of photonic device arrays through multiplexing of the reference value generation circuit, thereby solving the bottleneck problem of large-scale photonic device array applications. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a schematic diagram of the self-reference analog control loop for photonic device parameter stability provided by the present application;

[0048] Figure 2 is a schematic diagram of an analog control core circuit provided by the present application;

[0049] Figure 3 is a schematic diagram of another analog control core circuit provided by the present application;

[0050] Figure 4 is a schematic diagram of a reference value generation circuit provided by the present application;

[0051] Figure 5 is a logic flow diagram of a digital finite state machine provided by the present application;

[0052] Figure 6 is a schematic diagram of a self-referencing analog control loop for ring resonator wavelength locking provided by the present application;

[0053] Figure 7 is a schematic diagram of a self-referencing analog control loop for ring modulator wavelength locking provided by the present application;

[0054] Figure 8 is a schematic diagram of a self-referencing analog control loop for Mach-Zehnder bias point stabilization provided by the present application;

[0055] Figure 9 is a schematic diagram of an analog control loop for photonic device array parameter stabilization and a multiplexed reference value generation circuit provided by the present application. DETAILED DESCRIPTION

[0056] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application 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 only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0057] The content involved in the above embodiments will be described below with reference to a preferred embodiment.

[0058] As shown in Figure 1 , a self-referencing analog control loop for photonic device parameter stabilization includes a reference value generation circuit and a photonic device analog control loop;

[0059] The photonic device analog control loop includes a photonic device, a monitoring unit, an analog front end, an analog control core circuit, an output stage and an actuator connected in sequence; the reference value generation circuit is connected with the analog front end and the analog control core circuit;

[0060] The monitoring unit is configured to obtain an optical signal of the photonic device and generate an initial electrical signal;

[0061] The analog front end is configured to process the initial electrical signal and output a processed electrical signal.

[0062] The reference value generation circuit is configured to generate a reference value signal and a switch control signal according to the processed electrical signal and output them to the analog control core circuit; the reference value generation circuit comprises a comparator, a digital finite state machine and a digital-to-analog conversion module; the comparator compares the processed electrical signal with the reference value signal generated by the digital-to-analog conversion module to generate a comparison result; the digital finite state machine generates a switch control signal and a digital reference value for controlling the analog control core circuit according to the comparison result; and the digital-to-analog conversion module generates a reference value signal according to the digital reference value.

[0063] The analog control core circuit is configured to generate an analog control signal according to the processed electrical signal, the reference value signal and the switch control signal and output it to an output stage; the analog control core circuit comprises an operational amplifier and a switch; the processed electrical signal and the reference value signal are calculated by the operational amplifier to generate the analog control signal; and the switch control signal is used to control the state of the switch and select the in-phase input terminal or the anti-phase input terminal of the operational amplifier for inputting the processed electrical signal and the reference value signal.

[0064] The output stage is configured to generate a driving signal according to the analog control signal and output it to the actuator.

[0065] The actuator is configured to generate an execution signal according to the driving signal and adjust the optical parameter of the photonic device according to the execution signal.

[0066] The analog control core circuit comprises two structures.

[0067] One of the two structures is as shown in Figure 2 The analog control core circuit comprises a first operational amplifier A, a second operational amplifier B and a first switch 1.

[0068] The in-phase input terminal of the first operational amplifier A and the anti-phase input terminal of the second operational amplifier B both receive the processed electrical signal; and the anti-phase input terminal of the first operational amplifier A and the in-phase input terminal of the second operational amplifier B both receive the reference value signal.

[0069] The output terminals of the first operational amplifier A and the second operational amplifier B, together with the first switch 1, form a single-pole double-throw switch, which is switched according to the switch control signal. When the first switch 1 is connected to the output terminal of the first operational amplifier A, the analog control core circuit outputs an analog control signal obtained by differential operation of the processed electrical signal and the reference value signal. When the first switch 1 is connected to the output terminal of the second operational amplifier B, the analog control core circuit outputs an analog control signal obtained by differential operation of the reference value signal and the processed electrical signal.

[0070] The electrical signal processed by the analog front end and the reference value signal generated by the reference value generation circuit are input to operational amplifier A and operational amplifier B; the switch control signal generated by the reference value generation circuit controls the first switch 1 to switch operational amplifier A or operational amplifier B for output.

[0071] Secondly, such as Figure 3 As shown, the analog control core circuit includes a third operational amplifier C and a first switch 1;

[0072] The first switch 1 is a combination switch, used to select whether to connect the processed electrical signal and the reference signal to the non-inverting input terminal and the inverting input terminal of the third operational amplifier C, respectively, or to connect the processed electrical signal and the reference signal to the inverting input terminal and the non-inverting input terminal of the third operational amplifier C, respectively.

[0073] The processed electrical signal output from the analog front end and the reference value signal generated by the reference value generation circuit are both input to the first switch 1. The switch control signal generated by the reference value generation circuit controls the first switch 1 to switch the processed electrical signal and the reference value signal to the third operational amplifier C. Specifically, this includes: connecting the processed electrical signal to the non-inverting input terminal of the third operational amplifier C, and simultaneously connecting the reference value signal to the inverting input terminal of the third operational amplifier C; or, connecting the processed electrical signal to the inverting input terminal of the third operational amplifier C, and simultaneously connecting the reference value signal to the non-inverting input terminal of the third operational amplifier C.

[0074] Among them, such as Figure 4 As shown, the working principle of the reference value generation circuit includes: the comparator compares the electrical signal processed by the front end with the reference value signal generated by the digital-to-analog converter module, thereby generating a comparison result for the digital finite state machine; the digital finite state machine generates a switch control signal and a digital reference value signal for controlling the switch based on the comparison result; and the digital-to-analog converter module generates an analog reference value signal based on the digital reference value.

[0075] The process of generating reference value signals and switching control signals by the reference value generation circuit includes:

[0076] The digital finite state machine is used to initialize the upper reference register and the lower reference register. The value of the upper reference register and the value of the lower reference register differ by a fixed value. The digital-to-analog converter output signal corresponding to the lower reference register is less than the current processed electrical signal.

[0077] The comparator is used to compare the processed electrical signal with the digital-to-analog converter output signal corresponding to the lower reference register to obtain a comparison result.

[0078] When the comparison result is greater than, the digital finite state machine synchronously increments the values ​​of the upper reference register and the lower reference register; when the comparison result is less than, the digital finite state machine synchronously decrements the values ​​of the upper reference register and the lower reference register, and when the comparison result of the previous moment was greater than, the switch control signal is inverted.

[0079] The self-referenced analog control loop for stabilizing photonic device parameters provided in this invention has the advantages of simple structure and easy on-chip implementation. The core analog control circuit consists only of operational amplifiers and switches, while the reference value generation circuit consists of comparators, finite state machines, and a digital-to-analog converter module, consuming minimal hardware resources. This overcomes the disadvantages of traditional closed-loop control methods based on digital control algorithms, such as complex structure and difficulty in large-scale integration.

[0080] Optionally, the photonic device is a ring resonator, a ring modulator, or a Mach-Zehnder modulator.

[0081] Optionally, the actuator is an integrated heater or a PN junction;

[0082] The integrated heater adjusts the optical parameters of the photonic device through the thermo-optical effect;

[0083] The PN junction adjusts the optical parameters of the photonic device through the electro-optic effect.

[0084] like Figure 6 As shown, when a ring modulator is used in the photonic device, a photodiode is used in the monitoring unit, a transimpedance amplifier is used in the analog front end, a heater driver is used in the output stage, and an integrated heater is used in the actuator. The self-referenced analog control loop modulates the optical parameters of the photonic device, as follows:

[0085] Step 1: The photodiode monitors the light intensity at the download port or through port of the ring resonator and converts it into an initial electrical signal that corresponds to the light intensity. The initial electrical signal is a current signal.

[0086] Step 2: The transimpedance amplifier converts the initial electrical signal into a processed electrical signal, that is, converts the current signal into a voltage signal;

[0087] Step three, the reference value generation circuit obtains the digital switch control signal and the reference value signal by detecting the voltage signal output by the transimpedance amplifier, and inputs the digital switch control signal and the reference value signal into the analog control core circuit;

[0088] Step four, the analog control core circuit generates the analog control signal according to the voltage signal output by the transimpedance amplifier and the switch control signal and the reference value signal output by the reference value generation circuit;

[0089] Step five, the heater driver generates the driving signal according to the analog control signal;

[0090] Step six, the integrated heater heats according to the driving signal, so as to change the resonant wavelength of the ring resonator.

[0091] In step three, the specific process in which the reference value generation circuit obtains the switch control signal and the reference value signal is shown in Figure 5 and includes the following steps:

[0092] S1, initialization, setting the upper reference register, the lower reference register and the switch control signal register; wherein the value of the upper reference register and the value of the lower reference register are different by a fixed value, and the digital-to-analog conversion output signal corresponding to the lower reference register is less than the current obtained processed electrical signal.

[0093] S2, compare the current processed electrical signal with the digital-to-analog conversion output signal corresponding to the lower reference register to obtain a comparison result and save it; if the comparison result is greater, execute S3; if the comparison result is less, execute S4.

[0094] S3, synchronously increment the value of the upper reference register and the value of the lower reference register; return to execute S2.

[0095] S4, synchronously decrement the value of the upper reference register and the value of the lower reference register; execute S5.

[0096] S5, obtain and compare the processed electrical signal at the last time and the digital-to-analog conversion output signal corresponding to the lower reference register at the last time, that is, obtain the comparison result at the last time; if the comparison result is greater, execute S6; if the comparison result is less, return to execute S2.

[0097] S6, output the switch control signal after inversion.

[0098] The reference value generation circuit provided in the embodiment automatically updates the reference value signal and the switch control signal through the above steps, avoiding the problem of manually setting the reference value in the traditional method.

[0099] Meanwhile, the working frequency of the digital circuit used in the traditional method depends on the clock signal in the digital circuit; when the clock signal frequency is slow, the digital circuit working frequency is low, which can not compensate for the rapidly changing optical parameters; when the clock signal frequency is high, the digital circuit working frequency is high, which can cause greater power consumption, and can not meet the application requirements of low power consumption.

[0100] In this embodiment, only digital circuits are used as reference value generating circuits, so the frequency of the digital circuits does not affect the control speed of the analog control loop, thereby breaking the clock frequency limitation on performance, and overcoming the bottleneck problem caused by the clock frequency in the traditional control method.

[0101] Further, in an alternative embodiment, the actuator is a PN junction; the PN junction adjusts the resonant wavelength of the ring resonator through the electro-optic effect.

[0102] As shown in Figure 7 When the photonic device uses a ring modulator, the monitoring unit uses a photodiode, the analog front end uses a high-speed detection front end, the output stage is a heater driver, the actuator uses an integrated heater, and the self-reference analog control loop realizes the modulation of the optical parameters of the photonic device, the process is as follows:

[0103] Step one, load the modulation signal to the modulation structure of the ring modulator, so as to modulate the modulation signal to the optical signal;

[0104] Step two, the photodiode monitors the optical intensity of the download port or the straight-through port of the ring modulator, and converts it into a current signal corresponding to the optical intensity and varying with the modulation signal;

[0105] Step three, the high-speed detection front end converts the current signal corresponding to the optical intensity and varying with the modulation signal into a voltage signal varying only with the optical intensity;

[0106] Step four, the reference value generating circuit obtains the switching control signal and the reference value signal from the voltage signal output by the high-speed detection front end, and inputs them into the analog control core circuit;

[0107] Step five, the analog control core circuit generates an analog control signal according to the voltage signal output by the high-speed detection front end, the switching control signal and the reference value signal output by the reference value generating circuit;

[0108] Step six, the heater driver generates a driving signal according to the analog control signal;

[0109] Step seven, the integrated heater heats according to the driving signal, thereby changing the resonant wavelength of the ring modulator.

[0110] By adding a modulation signal to the ring modulator, the optical signal output of the ring modulator is changed, and the transmission of the signal is realized.

[0111] Further, in an alternative embodiment, the actuator is a PN junction; the PN junction adjusts the resonance wavelength of the ring resonator through electro-optic effect.

[0112] As shown in the figure, when the photonic device is a Mach-Zehnder modulator, the monitoring unit is a photodiode, the analog front end is a trans-impedance amplifier, the output stage is a heater driver, the actuator is an integrated heater, and a self-referenced analog control loop is used to modulate the optical parameter of the photonic device, the process is as follows: Figure 8 Step one, the photodiode monitors the light intensity of the Mach-Zehnder interferometer and converts it into a current signal corresponding to the light intensity;

[0113] Step two, the trans-impedance amplifier converts the current signal into a voltage signal;

[0114] Step three, the reference value generation circuit obtains the switch control signal and the reference value signal by detecting the voltage signal output by the trans-impedance amplifier, and inputs them into the analog control core circuit;

[0115] Step four, the analog control core circuit generates an analog control signal according to the voltage signal output by the trans-impedance amplifier and the switch control signal and the reference value signal output by the reference value generation circuit;

[0116] Step five, the heater driver generates a driving signal according to the analog control signal;

[0117] Step six, the integrated heater heats according to the driving signal, thereby changing the bias point of the Mach-Zehnder interferometer.

[0118] Further, in an alternative embodiment, the actuator is a PN junction; the PN junction adjusts the bias point of the Mach-Zehnder interferometer through electro-optic effect.

[0119] On the basis of the above-mentioned embodiments, optionally, the analog control core circuit further comprises a second switch 2, a third switch 3 and a buffer stage;

[0120] The second switch 2 is connected to a power supply, the third switch 3 is grounded, and the second switch 2 and the third switch 3 are connected in series; the input end of the buffer stage is connected to the output end of the operational amplifier, and the output end of the buffer stage serves as the output end of the analog control core circuit;

[0121] When the second switch 2 is closed, it is used to set the analog control signal output by the operational amplifier to the power supply voltage;

[0122] When the third switch 3 is closed, it is used to set the analog control signal output by the operational amplifier to zero voltage;

[0123] When the third switch 3 is closed, it is used to set the analog control signal output by the operational amplifier to zero voltage;

[0124] The buffer stage is an amplifier used to amplify the analog control signal.

[0125] Since the operational amplifier output has a limited switching speed from low to high, it is necessary to shorten the switching time of the analog control core circuit output. Therefore, closing the second switch 2 and setting the analog control signal output by the operational amplifier to the power supply voltage can speed up the switching speed of the analog control core circuit output from low to high.

[0126] Since the operational amplifier's output has a limited high-to-low switching speed, it is necessary to shorten the switching time of the analog control core circuit output. Therefore, closing the second switch 3 and setting the analog control signal output by the operational amplifier to zero voltage can speed up the high-to-low switching speed of the analog control core circuit output.

[0127] The buffer can be an inverter, used to invert the analog control signal output by the operational amplifier before outputting it to the output stage.

[0128] Based on the above embodiments, optionally, the photonic device simulation control loop has n loops. When n=1, it is the self-reference simulation control loop for stabilizing photonic device parameters provided in the above embodiments.

[0129] like Figure 9 As shown, when n≥2, the self-referenced analog control loop further includes an analog front-end output multiplexer, a reference value signal demultiplexer, and a switch control signal demultiplexer;

[0130] The analog front ends of the n analog control loops of the photonic devices are all connected to the analog front end output multiplexer, and the analog control core circuits are all connected to the reference value signal demultiplexer and the switch control signal demultiplexer.

[0131] The reference value generation circuit is used to sequentially receive the processed electrical signals from the n analog control loops of the photonic devices, and output a switch control signal and a reference value signal.

[0132] like Figure 9 As shown, when the photonic device uses a ring modulator array, the monitoring unit uses a photodiode array, the analog front end uses a transimpedance amplifier array, the output stage is a heater driver array, and the actuator uses an integrated heater array. The self-referenced analog control loop modulates the optical parameters of the photonic device, as follows:

[0133] Step 1: The photodiode array monitors the light intensity at the download port or through port of the ring resonator array and converts it into a current signal that corresponds to the light intensity.

[0134] Step 2: The transimpedance amplifier array converts the current signal into a voltage signal;

[0135] Step three, the analog front-end output multiplexer, reference value signal demultiplexer and switch control signal demultiplexer are switched to the first ring resonator;

[0136] Step four, the reference value generation circuit obtains the switch control signal and the reference value signal by detecting the voltage signal of the front-end output, and inputs the switch control signal and the reference value signal into the reference value signal demultiplexer and the switch control signal demultiplexer, and outputs the switch control signal and the reference value signal to the corresponding analog control core circuit after demultiplexing;

[0137] Step five, the analog control core circuit generates an analog control signal according to the voltage signal, the switch control signal and the reference value signal output by the reference value generation circuit;

[0138] Step six, the heater driving array generates a driving signal according to the analog control signal;

[0139] Step seven, the integrated heater array heats according to the driving signal, so as to change the resonant wavelength of the ring resonator array;

[0140] Step eight, the analog front-end output multiplexer, the reference value signal demultiplexer and the switch control signal demultiplexer are switched to the next ring resonator, and steps four to eight are repeated.

[0141] Since the area of the digital finite state machine is large and the power is high, in the embodiment, the reference value generation circuit is multiplexed to effectively control the photonic device array, reduce the chip area and power consumption, and solve the bottleneck problem of large-scale photonic device array application.

[0142] On the basis of the above-mentioned embodiments, the application further provides a control method of a self-reference analog control loop for photonic device parameter stability, which is suitable for the self-reference analog control loop for photonic device parameter stability in any one of the above-mentioned embodiments, and comprises the following steps:

[0143] The monitoring unit obtains the optical signal of the photonic device and generates an initial electrical signal;

[0144] The analog front-end processes the initial electrical signal and outputs a processed electrical signal;

[0145] The reference value generation circuit generates a reference value signal and a switch control signal according to the processed electrical signal and outputs the reference value signal and the switch control signal to the analog control core circuit;

[0146] The analog control core circuit generates an analog control signal according to the processed electrical signal, the reference value signal and the switch control signal and outputs the analog control signal to the output stage;

[0147] The output stage generates a driving signal according to the analog control signal and outputs the driving signal to the actuator;

[0148] The actuator generates an actuation signal from the drive signal and adjusts an optical parameter of the photonic device in accordance with the actuation signal.

[0149] The self-referencing analog control loop for photonic device parameter stabilization provided by the embodiment of the present application can execute the control method of the self-referencing analog control loop for photonic device parameter stabilization provided by any embodiment of the present application, and has the corresponding function modules and beneficial effects.

[0150] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A self-referencing analog control loop for parameter stabilization of photonic devices, characterized in that, The reference value generation circuit and the photonic device analog control loop are connected in sequence. The photonic device analog control loop comprises a photonic device, a monitoring unit, an analog front end, an analog control core circuit, an output stage and an actuator connected in sequence. The monitoring unit is configured to acquire an optical signal of the photonic device and generate an initial electrical signal. The analog front end is configured to process the initial electrical signal and output a processed electrical signal. The reference value generation circuit comprises a comparator, a digital finite state machine and a digital-to-analog conversion module. The digital finite state machine generates a switch control signal and a digital reference value for controlling the analog control core circuit according to the comparison result. The digital-to-analog conversion module generates a reference value signal according to the digital reference value. The analog control core circuit comprises an operational amplifier and a switch. The processed electrical signal and the reference value signal are input into the same-phase input terminal or the inverse-phase input terminal of the operational amplifier through the switch controlled by the switch control signal.

2. The self-referencing analog control loop of claim 1, wherein, The output stage is configured to generate a driving signal according to the analog control signal and output the driving signal to the actuator. The actuator is configured to generate an execution signal according to the driving signal and adjust the optical parameter of the photonic device according to the execution signal. The analog control core circuit comprises a first operational amplifier, a second operational amplifier and a first switch.

3. The self-referencing analog control loop of claim 1, wherein, The same-phase input terminal of the first operational amplifier and the inverse-phase input terminal of the second operational amplifier receive the processed electrical signal. The inverse-phase input terminal of the first operational amplifier and the same-phase input terminal of the second operational amplifier receive the reference value signal.

4. A self-referencing analog control loop as claimed in claim 2 or 3, characterized in that, The output terminal of the first operational amplifier and the output terminal of the second operational amplifier and the first switch constitute a single-pole double-throw switch. When the first switch is connected to the output terminal of the first operational amplifier, the analog control core circuit outputs the analog control signal obtained by differentiating the processed electrical signal and the reference value signal. When the first switch is connected to the output terminal of the second operational amplifier, the analog control core circuit outputs the analog control signal obtained by differentiating the reference value signal and the processed electrical signal. The analog control core circuit comprises a third operational amplifier and a first switch. The first switch is a combination switch. The analog control core circuit further comprises a second switch, a third switch and a buffer stage. The second switch is connected to a power supply, the third switch is connected to a ground, and the second switch and the third switch are connected in series; an input end of the buffer stage is connected to an output end of the operational amplifier, and an output end of the buffer stage is used as an output end of the analog control core circuit; When the second switch is closed, the analog control signal output by the operational amplifier is set to a power supply voltage; When the third switch is closed, the analog control signal output by the operational amplifier is set to zero voltage; The buffer stage is an amplifier, which is used to amplify the analog control signal.

5. The self-referencing analog control loop of claim 1, wherein, The implementation process of the reference value generation circuit for generating the reference value signal and the switch control signal comprises: The digital finite state machine initializes the upper reference register and the lower reference register, the value of the upper reference register and the value of the lower reference register differ by a fixed value, and the digital-to-analog conversion output signal corresponding to the lower reference register is less than the processed electrical signal; The comparator compares the processed electrical signal with the digital-to-analog conversion output signal corresponding to the lower reference register to obtain a comparison result; When the comparison result is greater than, the digital finite state machine synchronously increments the value of the upper reference register and the value of the lower reference register; when the comparison result is less than, the digital finite state machine synchronously decrements the value of the upper reference register and the value of the lower reference register, and when the comparison result of the previous moment is greater than, the switch control signal is inverted.

6. The self-referencing analog control loop of claim 1, wherein, The actuator is an integrated heater or a PN junction; The integrated heater adjusts the optical parameter of the photonic device through a thermo-optic effect; The PN junction adjusts the optical parameter of the photonic device through an electro-optic effect.

7. The self-referencing analog control loop of claim 1, wherein, The photonic device is a ring resonator, a ring modulator or a Mach-Zehnder modulator.

8. The self-referencing analog control loop of claim 1, wherein, When n is greater than or equal to 2, the self-reference analog control loop further comprises an analog front-end output multiplexer, a reference value signal demultiplexer and a switch control signal demultiplexer; The analog front-ends of the n analog control loops are connected to the analog front-end output multiplexer, and the analog control core circuits are connected to the reference value signal demultiplexer and the switch control signal demultiplexer; The reference value generation circuit is used to sequentially receive the processed electrical signals of the n analog control loops, and output the switch control signal and the reference value signal.

9. A control method for a self-referenced analog control loop for photonic device parameter stabilization, suitable for use in a self-referenced analog control loop for photonic device parameter stabilization according to any of claims 1-8, characterized in that, It comprises: The monitoring unit obtains the optical signal of the photonic device and generates an initial electrical signal; The analog front-end processes the initial electrical signal and outputs a processed electrical signal; The reference value generation circuit generates a reference value signal and a switch control signal according to the processed electrical signal and outputs them to the analog control core circuit; The analog control core circuit generates an analog control signal according to the processed electrical signal, the reference value signal and the switch control signal and outputs it to the output stage; The output stage generates a driving signal according to the analog control signal and outputs it to the actuator; The actuator generates an execution signal according to the driving signal, and adjusts the optical parameter of the photonic device according to the execution signal.

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