CN111381323B

CN111381323B - Control circuit and method

Info

Publication number: CN111381323B
Application number: CN201811640501.0A
Authority: CN
Inventors: 陈涛; 张州
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2023-02-28
Anticipated expiration: 2038-12-29
Also published as: WO2020134321A1; CN111381323A

Abstract

The application discloses control circuit includes: the photoelectric conversion sub-circuit is used for converting the optical signal output by the double-ring resonator to obtain output current; the signal processing sub-circuit is used for obtaining current with preset frequency from the output current; determining an adjustment strategy based on the obtained current; and the feedback control sub-circuit is used for adjusting the bias direct current acting on the micro-ring of the double-ring resonator based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal. The application also discloses a control method.

Description

Control circuit and method

Technical Field

The present application relates to the field of optical communication technologies, and in particular, to a control circuit method.

Background

At present, in a silicon-based photonic integrated device, a microring resonator has the advantages of enhanced resonance to specific wavelengths, controllable direction and path of optical transmission, compact structure, large design freedom, convenience for integration with other devices, and the like, and thus becomes one of the most important basic functional units in a photonic integrated circuit. The double-ring resonator is used as one micro-ring resonator and can realize the same side of the input end and the output end. Since the silicon optical micro-ring of the double-ring resonator has great sensitivity to process errors and temperature changes, automatic calibration of the wavelength is essential. In the related art, two micro-rings of a double-ring resonator are respectively subjected to scanning test, and an optimal parameter corresponding to a central wavelength is searched for fixing so as to lock the central wavelength.

The mode respectively carries out the scanning test on the two micro-rings of the double-ring resonator, and has complex operation and low efficiency.

Disclosure of Invention

In order to solve the related technical problems, embodiments of the present application provide a control circuit and a method.

The technical scheme of the embodiment of the application is realized as follows:

an embodiment of the present application provides a control circuit, including:

the photoelectric conversion sub-circuit is used for converting the optical signal output by the double-ring resonator to obtain output current;

the signal processing sub-circuit is used for obtaining current with preset frequency from the output current; determining an adjustment strategy based on the obtained current;

and the feedback control sub-circuit is used for adjusting the bias direct current acting on the double-ring resonator micro-ring based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal.

The embodiment of the application provides a control method, which is applied to a control circuit and comprises the following steps:

converting the optical signal output by the double-ring resonator to obtain an output current;

obtaining a current with a preset frequency from the output current; determining an adjustment strategy based on the obtained current;

and adjusting the bias direct current acting on the micro-ring of the double-ring resonator based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal.

According to the control circuit and the method provided by the embodiment of the application, a photoelectric conversion sub-circuit in the control circuit converts an optical signal output by a double-ring resonator to obtain an output current; a signal processing sub-circuit in the control circuit obtains current with preset frequency from the output current; determining an adjustment strategy based on the obtained current; and a feedback control sub-circuit in the control circuit adjusts the bias direct current acting on the double-ring resonator micro-ring based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal. By adopting the scheme of the embodiment of the application, the bias direct current is adjusted through the change of the extracted current with the preset frequency, the resonance wavelengths of the two micro-rings of the double-ring resonator can be automatically locked, independent scanning test on each micro-ring is not needed, and the operation is simple; in addition, the two micro-rings can be locked simultaneously, and the center wavelength can be locked quickly compared with the mode that only one micro-ring can be locked at a time.

Drawings

Fig. 1 is a schematic structural view of a double-ring resonator in the related art;

FIG. 2 is a first schematic diagram illustrating a control circuit according to an embodiment of the present disclosure;

FIG. 3a is a graph illustrating the coupling efficiency curves of the double-ring resonator according to the embodiment of the present application;

FIG. 3b is a schematic diagram illustrating a structure of a control circuit according to an embodiment of the present invention;

FIG. 3c is a schematic diagram of a third exemplary embodiment of a control circuit;

FIG. 4 is a fourth schematic diagram illustrating a control circuit according to an embodiment of the present disclosure;

FIG. 5 is a fifth schematic diagram illustrating a control circuit according to an embodiment of the present disclosure;

FIG. 6 is a schematic flow chart illustrating the implementation of calibrating the resonant wavelength of ring 1 according to the embodiment of the present application;

FIG. 7 is a schematic flow chart illustrating the implementation of the calibration of the resonant wavelength of the ring 2 according to the embodiment of the present application;

fig. 8 is a schematic flow chart of an implementation of a control method according to an embodiment of the present application.

Detailed Description

The present application will be described in further detail with reference to the drawings and examples.

The 21 st century is a highly information-oriented age, and the transmission, processing and storage of information are faced with higher and higher requirements. The traditional electrical interconnection technology is facing to the electronic bottlenecks of signal delay, power consumption, heat dissipation and the like, and the replaced optical interconnection technology is widely applied to the field of information processing due to the advantages of high transmission rate, electromagnetic crosstalk resistance, large transmission bandwidth, low transmission energy consumption and the like. Silicon-on-Insulator (SoI) is the most popular optical interconnection platform with low cost and high integration level due to its advantages of transparency in the communication band, large refractive index difference, and complete compatibility with standard CMOS (Complementary-Metal-Oxide-Semiconductor) processes. Among a plurality of silicon-based photonic integrated devices, the microring resonator becomes one of the most important basic functional units in a photonic integrated circuit because of the advantages of enhanced resonance to specific wavelengths, controllable direction and path of optical transmission, compact structure, large design freedom, convenience for integration with other devices and the like. The micro-ring resonator can not realize the same side of the input end and the same side of the output end by applying a wider single-ring resonator theoretically, if an optical field on the same side meets more crossed waveguides in transmission, the loss is increased, and the micro-ring resonator is limited in networking application of fifth Generation mobile communication (5G, 5fifth Generation).

The double-ring resonator can realize the same side of the input end and the same side of the output end theoretically. Fig. 1 is a schematic structural diagram of a double-ring resonator in the related art, and as shown in fig. 1, the double-ring resonator includes two silicon optical microrings (ring 1 and ring 2 shown in fig. 1), one uplink waveguide, one downlink waveguide, a heater 1, and a heater 2. Wherein the uplink waveguide is located above one ring 2 for inputting optical signals; the downstream waveguide is located below the ring 1 and is used for outputting optical signals. The silicon optical micro-ring, namely the silicon-based waveguide micro-ring, is used for coupling the optical waveguide which closely propagates to the micro-ring through an evanescent field to generate resonance. The heater 1 is wrapped on the ring 1 and used for heating the ring 1; the heater 2 is wrapped around the ring 2 for heating the ring 2.

Since the silicon optical micro-ring has great sensitivity to process errors and temperature changes, automatic calibration of wavelength and automatic compensation of temperature drift are essential in large-scale application. Currently, for a double-ring resonator, the process of implementing wavelength calibration is: firstly, respectively carrying out scanning test on parameters of the two silicon optical micro-rings, searching for an optimal parameter corresponding to the central wavelength, and solidifying the optimal parameter to lock the central wavelength. Wherein, the central wavelength may refer to a central wavelength of an input optical signal. Assuming that the wavelength range of the input optical signal is 420 nm to 760 nm, the center wavelength may be 510 nm.

However, the above wavelength calibration method requires a scan test for each micro-ring, which is inefficient; the flexibility is not enough, and if the performance of the micro-ring is deteriorated, the curing parameters are gradually invalid; in addition, the on-line wavelength can not be locked quickly and accurately.

Based on this, in various embodiments of the present application, the optical-to-electrical conversion sub-circuit in the control circuit converts the optical signal output by the double-ring resonator to obtain an output current; a signal processing sub-circuit in the control circuit obtains current with preset frequency from the output current; determining an adjustment strategy based on the obtained current; and a feedback control sub-circuit in the control circuit adjusts the bias direct current acting on the double-ring resonator micro-ring based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal.

An embodiment of the present application provides a control circuit, as shown in fig. 2, the control circuit includes:

a photoelectric conversion sub-circuit 21 for converting an optical signal output from the double-ring resonator to obtain an output current;

a signal processing sub-circuit 22 for obtaining a current of a preset frequency from the output current; determining an adjustment strategy based on the obtained current;

and the feedback control sub-circuit 23 is configured to adjust a bias dc current acting on the micro-ring of the double-ring resonator based on the adjustment strategy, so as to lock a resonant wavelength of the double-ring resonator as a center wavelength of the input optical signal.

In practical application, the intensity variation trend of the optical signal output by the double-ring resonator can be used as a basis for adjusting the corresponding bias direct current applied to the micro-ring. It is also simpler to implement since it does not involve the use of other complex algorithms such as quadrature demodulation algorithms and the like to achieve the lock on center wavelength.

Based on this, in an embodiment, the photoelectric conversion sub-circuit 21 is specifically configured to detect an optical signal output by the double-ring resonator, and perform conversion processing on the optical signal to obtain an output current; the optical signal is output by the double-ring resonator after a first current and a second current are respectively applied to two micro-rings of the double-ring resonator; the first current is obtained by superposing a first bias direct current and a first preset alternating current; the second current is obtained by superposing a second bias direct current and a second preset alternating current. The frequency of the first preset alternating current is a first frequency, and the frequency of the second preset alternating current is a second frequency.

Wherein, the micro-ring can be a silicon optical micro-ring. The optical signal output by the double-ring resonator may be obtained by coupling the input optical signal by two micro-rings in the double-ring resonator.

In practical application, in order to realize simultaneous control of the two micro-rings, two paths of alternating current signals can be extracted from the output current, and an adjustment strategy for adjusting corresponding bias direct current is obtained based on the two paths of alternating current signals.

Based on this, in an embodiment, the signal processing sub-circuit 22 is specifically configured to perform filtering processing on the output current to obtain a first sub-current with a first frequency and a second sub-current with a second frequency; determining a first adjustment strategy for adjusting the first bias direct current based on the first sub-current; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current.

In practical application, in order to improve the locking efficiency, the resonance wavelengths of the two micro-rings can be simultaneously locked to the central wavelength by using the determined corresponding adjustment strategy.

The feedback control sub-circuit 23 is specifically configured to adjust the first bias direct current based on the first adjustment strategy, and adjust the second bias direct current based on the second adjustment strategy, so that the resonant wavelengths of the two micro-rings of the dual-ring resonator both reach the center wavelength.

Wherein the central wavelength may refer to a central wavelength of an input optical signal of the double-ring resonator.

Fig. 3a is a coupling efficiency curve of the double-ring resonator, the abscissa indicates the resonance wavelengths of the two micro-rings, and the ordinate indicates the coupling efficiency, and it can be seen from fig. 3a that the coupling efficiency is the maximum when the resonance wavelengths of both micro-rings of the double-ring resonator reach the center wavelength, that is, the optical power output by the double-ring resonator is the maximum.

In practical application, in order to make the resonant wavelengths of the two micro-rings of the double-ring resonator reach the central wavelength, the resonant wavelengths of the two micro-rings may be calibrated first coarsely and then finely. Through two-stage calibration, not only can the locking times be reduced, but also the center wavelength can be accurately locked, and therefore the locking precision and speed can be improved.

Based on this, a first bias current and a second bias current may be applied to the two micro-rings of the dual-ring resonator by the two heaters, respectively, so that a resonance wavelength of the corresponding micro-ring is approximately aligned with a center wavelength of an input optical signal of the dual-ring resonator.

In practical application, the process of performing fine calibration on the resonant wavelengths of the two micro-rings may be as follows: through the output current, the bias current applied to the two heaters is changed, and then the resonant wavelengths of the two micro-rings are influenced, so that the coupling optical power of the two micro-rings is changed, and further the output current obtained by the photoelectric conversion sub-circuit 21 is changed, therefore, the resonant wavelengths of the two micro-rings are adjusted for multiple times through the output current, and the resonant wavelength of the corresponding micro-ring can reach the central wavelength. In order to adjust the bias currents applied to the two heaters by the output current, the output current may be decoupled first to obtain two currents having the same frequency as the corresponding preset alternating current.

Based on this, in an embodiment, the signal processing sub-circuit 22 is specifically configured to: based on a first cut-off frequency, filtering the output current to obtain a first sub-current of a first frequency; and based on the second cut-off frequency, filtering the output current to obtain a second sub-current of a second frequency.

The larger the frequency difference between the first frequency and the second frequency is, the smaller the interference of the signal is when performing automatic locking, and thus, the better the obtained calibration effect is.

Here, the signal processing sub-circuit 22 includes two filters for filtering the output current; wherein the cut-off frequency of one filter is the first cut-off frequency, and the cut-off frequency of the other filter is the second cut-off frequency. The filter may be a low pass filter, a band pass filter, a high pass filter.

In practical application, in order to enable the resonant wavelength of the corresponding micro-ring to reach the central wavelength, the correlation between the output current and the first preset alternating current and the correlation between the output current and the second preset alternating current may be determined by using the two sub-currents obtained by decoupling the output current, the first preset alternating current and the second preset alternating current. The correlation may be used to adjust the bias dc applied to the heater.

The correlation may be that the output current is positively correlated with the first preset alternating current, for example, the output current increases with the increase of the first preset alternating current. The correlation relationship may also mean that the output current is negatively correlated with the first predetermined alternating current, for example, the output current decreases with the increase of the first predetermined alternating current.

Based on this, in one embodiment, the signal processing sub-circuit 22 further comprises a differential operation circuit;

the differential operation circuit is used for respectively carrying out differential operation processing on the corresponding sub-current and the corresponding preset alternating current aiming at each sub-current in the first sub-current and the second sub-current to obtain two operation results, and carrying out multiplication operation processing on the two operation results to obtain a corresponding processing result; taking the corresponding processing result as a corresponding correlation coefficient of the output current and the corresponding preset alternating current; the respective correlation coefficients are used to determine an adjustment strategy for adjusting the respective bias dc.

Specifically, the amplitudes of the first sub-current and the first preset alternating current may be periodically obtained, differential operation processing is performed on the obtained amplitude of the first sub-current and the obtained amplitude of the first preset alternating current respectively to obtain two operation results, and the two operation results are multiplied to obtain a first processing result; and taking the first processing result as a first correlation coefficient of the output current and the first preset alternating current. Similarly, the amplitude values of the second sub-current and the second preset alternating current may be periodically obtained, the amplitude value of the second sub-current and the amplitude value of the second preset alternating current are respectively subjected to differential operation processing to obtain two operation results, and the two operation results are subjected to multiplication operation processing to obtain a second processing result; and taking the second processing result as a second correlation coefficient of the output current and the second preset alternating current.

Here, a first correlation coefficient and a second correlation coefficient which characterize a variation trend of the output current may be determined by the amplitudes of the first sub-current and the second sub-current, so that the first correlation coefficient and the second correlation coefficient may be used as a basis for adjusting a corresponding bias dc applied to the micro-ring, and an adjustment strategy may be obtained. Because the amplitude of the current signal is extracted and the differential operation is combined, the adjustment strategy can be determined, the current signal does not need to be subjected to complex operation, the complexity is reduced, and the locking efficiency can be improved.

In practical application, if the output current is positively correlated with the first preset alternating current, the determined first correlation coefficient may be greater than zero; the determined first correlation coefficient may be less than zero if the output current is negatively correlated with the first preset alternating current. If the output current is positively correlated with the second preset alternating current, the determined second correlation number may be greater than zero; the second correlation number determined may be less than zero if the output current is negatively correlated with the second preset alternating current. In this way, a preset threshold may be set to determine the correlation of the output current with a corresponding preset alternating current.

Based on this, in an embodiment, the signal processing sub-circuit 22 is specifically configured to: judging whether the corresponding correlation coefficient is larger than a preset threshold value or not to obtain a judgment result; when the judgment result represents that the corresponding correlation coefficient is larger than a preset threshold value, determining that the output current is in positive correlation with the corresponding preset alternating current, and determining an adjustment strategy for increasing the corresponding bias direct current; and when the judgment result represents that the corresponding correlation coefficient is smaller than a preset threshold value, determining that the output current is in negative correlation with the corresponding preset alternating current, and determining an adjustment strategy for reducing the corresponding bias direct current. Wherein the preset threshold may be zero.

Here, from the coupling efficiency curve diagram shown in fig. 3a, it can be derived that the coupling efficiency gradually increases when the resonance wavelengths of the two micro-rings of the double-ring resonator are adjusted to increase toward the center wavelength; when the resonance wavelengths of the two micro-rings of the double-ring resonator reach the central wavelength, the coupling efficiency reaches the maximum value; when the resonance wavelengths of the two micro-rings of the double-ring resonator are adjusted to be increased towards a direction far away from the central wavelength, the coupling efficiency is gradually reduced. Here, the larger the coupling efficiency is, the larger the optical power output by the double-ring resonator is, the larger the output current obtained by the photoelectric conversion sub-circuit 21 is; the larger the resonant wavelength of the two microrings, the larger the bias current applied to the heater. In other words, when the resonance wavelength of the double-ring resonator is shorter than the center wavelength, the resonance wavelength of the double-ring resonator can be made closer to the center wavelength by increasing the bias current applied to the heater; when the resonance wavelength of the double-ring resonator is longer than the center wavelength, the resonance wavelength of the double-ring resonator can be closer to the center wavelength by reducing the bias current applied to the heater.

Based on this, in an embodiment, the feedback control sub-circuit 23 is specifically configured to: for each preset alternating current of the first preset alternating current and the second preset alternating current, increasing the corresponding bias direct current when the output current is in positive correlation with the corresponding preset alternating current; and when the output current and the corresponding preset alternating current are in negative correlation, reducing the corresponding bias direct current.

Specifically, when the output current is in positive correlation with the first preset alternating current, the first bias direct current is increased to increase the first current, so as to affect the resonant wavelength of the corresponding micro-ring, thereby causing a change in the coupled optical power of the corresponding micro-ring, and further causing a change in the output current obtained by the photoelectric conversion sub-circuit 21, so as to continuously increase the optical power output by the dual-ring resonator to reach the maximum optical power; when the output current is in negative correlation with the first preset alternating current, the first bias direct current is reduced to reduce the first current, so that the resonance wavelength of the corresponding micro ring is influenced, the coupling optical power of the corresponding micro ring is changed, the output current obtained by the photoelectric conversion sub-circuit 21 is changed, and the optical power output by the double-ring resonator is continuously increased to achieve the maximum optical power.

Similarly, when the output current is in positive correlation with the second preset alternating current, the second bias direct current is increased to increase the second current, so as to affect the resonant wavelength of the corresponding micro-ring, thereby causing the change of the coupled optical power of the corresponding micro-ring, and further causing the change of the output current obtained by the photoelectric conversion sub-circuit 21, so as to continuously increase the optical power output by the double-ring resonator to reach the maximum optical power; when the output current is negatively correlated with the second preset alternating current, the second bias direct current is reduced to reduce the second current, so that the resonance wavelength of the corresponding micro-ring is affected, the coupling optical power of the corresponding micro-ring is changed, the output current obtained by the photoelectric conversion sub-circuit 21 is changed, and the optical power output by the double-ring resonator is continuously increased to reach the maximum optical power.

By adopting the scheme of the embodiment of the application, the automatic locking of the resonance wavelengths of the two micro-rings of the double-ring resonator can be realized through the photoelectric conversion sub-circuit 21, the signal processing sub-circuit 22 and the feedback control sub-circuit 23 in the control circuit, the independent scanning test of each micro-ring is not needed, and the operation is simple. Here, locking can be achieved simultaneously for both micro-rings, enabling fast locking of the center wavelength relative to a way in which only one micro-ring can be locked at a time.

In addition, the center wavelength is locked through two-stage wavelength adjustment, in the first-stage wavelength adjustment process, corresponding bias direct currents are applied to the two micro rings of the double-ring resonator, so that the resonance wavelength of the micro rings of the double-ring resonator is approximately aligned with the center wavelength, in the second-stage wavelength adjustment process, corresponding preset alternating currents are applied to the two micro rings of the double-ring resonator, the output currents are obtained, based on the output currents, the corresponding bias currents corresponding to the micro rings are adjusted to influence the resonance wavelength of the corresponding micro rings, so that the coupling optical power of the corresponding micro rings is changed, and further the output currents obtained by the photoelectric conversion sub-circuit 21 are changed, and therefore the resonance wavelength of the corresponding micro rings can be locked to the center wavelength through adjustment of the output currents, and the optical power output by the double-ring resonator reaches the maximum value. Through two-stage wavelength calibration, not only can the accurate locking of center wavelength be realized, but also the quick locking of center wavelength can be realized, and then locking precision and speed can be improved.

The present application will be described in further detail with reference to the following application examples.

Application example 1

In the embodiment of the present application, as shown in fig. 3b and 3c, the method includes: the photoelectric conversion circuit comprises a double-ring resonator, a photoelectric conversion sub-circuit, a signal processing sub-circuit and a feedback control sub-circuit; wherein the double ring resonator comprises: two silicon optical micro-rings (ring 1, ring 2 in fig. 3 c), one uplink waveguide, one downlink waveguide, and two heaters. The uplink waveguide is positioned above the ring 2, the downlink waveguide is positioned below the ring 1, and the uplink waveguide, the downlink waveguide and the two silicon optical micro rings form an uplink and downlink double-ring resonator. The heater 1 is wrapped on the ring 1 and used for heating the ring 1 by applying voltage on the electrode of the heater 1; the heater 2 is wrapped around the ring 2 for heating the ring 2 by a voltage applied to an electrode of the heater 1. The photodetector is positioned on the light-emitting side of the downlink waveguide.

As shown in fig. 3c, the resonant wavelengths of the two silicon optical micro-rings are roughly calibrated, and the specific implementation process may include: a dc bias 1 (corresponding to the first bias dc described above) is input to the electrodes of the heater 1 to generate a bias voltage so that the resonance wavelength of the ring 1 is substantially aligned with the center wavelength. Similarly, a dc bias 2 (corresponding to the second bias dc described above) is input to the electrode of the heater 2 corresponding to the ring 2 to generate a second bias voltage so that the resonance wavelength of the ring 2 is substantially aligned with the center wavelength.

And then, performing fine calibration on the resonant wavelengths of the two silicon optical micro-rings, wherein the specific implementation process can comprise the following steps:

a control current obtained by superimposing the dc bias 1 and the dither signal 1 (corresponding to the first preset ac described above) is input to the electrode of the heater 1, and a control current obtained by superimposing the dc bias 2 and the dither signal 2 (corresponding to the second preset ac described above) is input to the electrode of the heater 2. And detecting the optical signal output by the double-ring resonator through a photoelectric detection sub-circuit, converting the optical signal to obtain an output current, and sending the output current to the signal processing module. Wherein, the dither signal 1 can be represented by mcos (f 1 t), the dither signal 2 can be represented by mcos (f 2 t), f1 represents the frequency of the dither signal 1, f2 represents the frequency of the dither signal 2, and f2 > 3f1.

The signal processing sub-circuit decouples the output current, namely, the output current is filtered to obtain a first path of current containing f1 and a second path of current containing f 2; determining a first correlation coefficient of the output current signal and the jitter signal 1 based on the first path of current; and determining a second correlation coefficient of the output current signal and the jittered signal 1 based on the second path of current. And the signal processing module sends the first correlation coefficient and the second correlation coefficient to the feedback control sub-circuit.

The feedback control sub-circuit increases a direct current bias 1 when it is determined that the output current signal is positively correlated with a jitter signal 1 based on the first correlation coefficient; reducing the DC offset 1 when it is determined that the output current is negatively correlated with the dither signal 1 based on the first correlation coefficient.

It should be noted that, the corresponding bias currents applied to the ring 1 and the ring 2 are adjusted to affect the resonant wavelengths of the ring 1 and the ring 2, so that the coupling optical powers of the ring 1 and the ring 2 change, and further the output current obtained by the photodetector changes, so that the resonant wavelengths of the ring 1 and the ring 2 are adjusted multiple times by the output current, and the resonant wavelengths of the ring 1 and the ring 2 can reach the central wavelength of the input optical signal of the double-ring resonator, and further the optical power output by the double-ring resonator reaches the maximum value.

Application example two

In the embodiment of the present application, as shown in fig. 4, the method includes: the photoelectric conversion circuit comprises a double-ring resonator, a photoelectric conversion sub-circuit, a low-pass filter, a band-pass filter, a differential operation circuit and a feedback control sub-circuit; wherein the double-ring resonator includes: two silicon optical micro-rings (ring 1, ring 2 in fig. 4), one path of ascending waveguide, one path of descending waveguide, and two heaters. The uplink waveguide is positioned above the ring 2, the downlink waveguide is positioned below the ring 1, and the uplink waveguide, the downlink waveguide and the two silicon optical micro rings form an uplink and downlink double-ring resonator. The heater 1 is wrapped on the ring 1 and used for heating the ring 1 by applying voltage on an electrode of the heater 1; the heater 2 is wrapped around the ring 2 for heating the ring 2 by applying a voltage on the electrodes of the heater 1. The photoelectric detector is positioned on the light-emitting side of the downlink waveguide.

The low-pass filter and the band-pass filter correspond to two filters included in the signal processing circuit 22, and the differential operation circuit corresponds to a differential operation circuit included in the signal processing circuit 22.

As shown in fig. 4, the resonant wavelengths of the two silicon optical micro-rings are roughly calibrated, and the specific implementation process may include: a dc bias 1 (corresponding to the first bias dc described above) is input to the electrodes of the heater 1 to generate a bias voltage so that the resonance wavelength of the ring 1 is substantially aligned with the center wavelength. Similarly, a dc bias 2 (corresponding to the second bias dc described above) is input to the electrode of the heater 2 corresponding to the ring 2 to generate a second bias voltage so that the resonance wavelength of the ring 2 is substantially aligned with the center wavelength.

a control current obtained by superimposing the dc bias 1 and the dither signal 1 (corresponding to the first preset ac described above) is input to the electrode of the heater 1, and a control current obtained by superimposing the dc bias 2 and the dither signal 2 (corresponding to the second preset ac described above) is input to the electrode of the heater 2. And detecting the optical signal output by the double-ring resonator through a photoelectric detector, converting the optical signal to obtain an output current, and respectively sending the output current to the low-pass filter and the band-pass filter. Wherein, the dither signal 1 can be represented by mcos (f 1 t), the dither signal 2 can be represented by mcos (f 2 t), f1 represents the frequency of the dither signal 1, f2 represents the frequency of the dither signal 2, and f2 > 3f1.

Decoupling the output current through two filters, namely filtering the output current through a low-pass filter to obtain a first path of current (shown as a signal a in fig. 4) containing f1, and filtering the output current through a band-pass filter to obtain a second path of current (shown as a signal b in fig. 4) containing f 2; determining a first correlation coefficient of the output current signal and a jitter signal 1 based on the signal a; and determining a second correlation coefficient of the output current signal with the jittered signal 1 based on the signal b. The low-pass filter sends the first correlation coefficient to the differential operation circuit, and the band-pass filter sends the second correlation coefficient to the differential operation circuit. Here, the cutoff frequency of the low-pass filter may be set to 2f1, the cutoff center frequency of the band-pass filter may be set to f2, and the pass bandwidth is set to f1.

The differential operation circuit respectively performs differential operation processing on the signal a and the jitter signal 1 to obtain two operation results, and performs multiplication operation processing on the two operation results to obtain a first processing result (which can be represented by a signal c); judging whether the first processing result is greater than zero, if so, determining that the output current is in positive correlation with the first preset alternating current, and increasing the bias 1 so as to change the resonance wavelength of the ring 1 to lock the center wavelength; if the first processing result is less than zero, it is determined that the output current is negatively correlated with the first preset alternating current and the direct current bias 1 is reduced, thereby changing the resonant wavelength of the ring 1 to lock onto the center wavelength.

Similarly, the signal b and the dither signal 2 are subjected to differential operation processing to obtain two operation results, and the two operation results are subjected to multiplication operation processing to obtain a second processing result (indicated by a signal d). Judging whether a second processing result is larger than zero, if so, determining that the output current is positively correlated with the second preset alternating current, and increasing a bias current 2; if the second processing result is less than zero, it is determined that the output current is negatively correlated with the second preset alternating current, and the bias current 2 is decreased.

It should be noted that, the corresponding bias currents applied to the ring 1 and the ring 2 are adjusted to affect the resonant wavelengths of the ring 1 and the ring 2, so that the coupled optical power of the ring 1 and the ring 2 changes, and further the output current obtained by the photodetector changes, so that the resonant wavelengths of the ring 1 and the ring 2 are adjusted multiple times through the output current, and the resonant wavelengths of the ring 1 and the ring 2 can reach the central wavelength of the input optical signal of the dual-ring resonator, and further the optical power output by the dual-ring resonator reaches the maximum value.

Application example three

In the embodiment of the present application, as shown in fig. 5, the method includes: the photoelectric conversion circuit comprises a double-ring resonator, a photoelectric conversion sub-circuit, a band-pass filter 1, a band-pass filter 2, a differential operation circuit and a feedback control sub-circuit; wherein the double-ring resonator includes: two silicon optical micro-rings (ring 1, ring 2 in fig. 5), one path of up waveguide, one path of down waveguide, and two heaters. The uplink waveguide is positioned above the ring 2, the downlink waveguide is positioned below the ring 1, and the uplink waveguide, the downlink waveguide and the two silicon optical micro rings form an uplink and downlink double-ring resonator. The heater 1 is wrapped on the ring 1 and used for heating the ring 1 by applying voltage on an electrode of the heater 1; the heater 2 is wrapped around the ring 2 for heating the ring 2 by applying a voltage on the electrodes of the heater 1. The photodetector is positioned on the light-emitting side of the downlink waveguide.

The band-pass filter 1 and the band-pass filter 2 correspond to two filters included in the signal processing circuit 22, and the differential operation circuit corresponds to a differential operation circuit included in the signal processing circuit 22.

As shown in fig. 5, the resonant wavelengths of the two silicon optical micro-rings are roughly calibrated, and the specific implementation process may include: a dc bias 1 (corresponding to the first bias dc described above) is input to the electrode of the heater 1 corresponding to the ring 1 to generate a bias voltage so that the resonance wavelength of the ring 1 is substantially aligned with the center wavelength. Similarly, a dc bias 2 (corresponding to the second bias dc described above) is input to the electrode of the heater 2 corresponding to the ring 2 to generate a second bias voltage so that the resonance wavelength of the ring 2 is substantially aligned with the center wavelength.

a control current obtained by superimposing the dc bias 1 and the dither signal 1 (corresponding to the first preset ac described above) is input to the electrode of the heater 1, and a control current obtained by superimposing the dc bias 2 and the dither signal 2 (corresponding to the second preset ac described above) is input to the electrode of the heater 2 corresponding to the ring 2. And detecting the optical signal output by the double-ring resonator through a photoelectric detector, converting the optical signal to obtain an output current, and sending the output current into the band-pass filter 1 and the band-pass filter 2 respectively. Wherein, the dither signal 1 can be represented by mcos (f 1 t), the dither signal 2 can be represented by mcos (f 2 t), f1 represents the frequency of the dither signal 1, f2 represents the frequency of the dither signal 2, and f2 > 3f1.

Decoupling the output current through two filters, that is, filtering the output current through a band-pass filter 1 to obtain a first path of current (shown as a signal a in fig. 5) including f1, and filtering the output current through a band-pass filter 2 to obtain a second path of current (shown as a signal b in fig. 5) including f 2; determining a first correlation coefficient of the output current and the jitter signal 1 based on the signal a; and determines a second correlation coefficient of the output current with the jittered signal 1 based on the signal b. The band-pass filter 1 sends the first correlation coefficient to the differential operation circuit, and the band-pass filter 2 sends the second correlation coefficient to the differential operation circuit. The cut-off center frequency of the band-pass filter 1 can be set to be f1, and the pass bandwidth is set to be f1; the cutoff center frequency of the band-pass filter 2 may be set to f2 and the pass bandwidth to f1.

The differential operation circuit respectively performs differential operation processing on the signal a and the jitter signal 1 to obtain two operation results, and performs multiplication operation processing on the two operation results to obtain a first processing result (which can be represented by a signal c); judging whether the first processing result is greater than zero, if so, determining that the output current is positively correlated with the first preset alternating current, and increasing the bias current 1 so as to change the resonance wavelength of the ring 1 to lock the center wavelength; if the first processing result is less than zero, it is determined that the output current is negatively correlated with the first preset alternating current and the bias current 1 is reduced, thereby changing the resonant wavelength of the ring 1 to lock onto the center wavelength.

Similarly, the signal b and the dither signal 2 are subjected to differential operation processing to obtain two operation results, and the two operation results are subjected to multiplication operation processing to obtain a second processing result (represented by a signal d). Judging whether a second processing result is larger than zero, if so, determining that the output current is positively correlated with the second preset alternating current, and increasing a bias current 2; if the second processing result is less than zero, it is determined that the output current is negatively correlated with the second preset alternating current, and the bias current 2 is decreased.

Based on the structure of the control circuit, fig. 6 is a schematic flow chart of the implementation of calibrating the resonant wavelength of the ring 1, as shown in fig. 6, including the following steps:

step 601: the differential operation circuit performs differential operation processing on the signal a and the jitter signal 1 respectively to obtain two operation results.

Wherein, the signal a represents that the output current is filtered to obtain a first path of current containing a first frequency; the dither signal 1 represents the first predetermined alternating current.

Step 602: the multiplier multiplies the two operation results to obtain a first processing result.

Step 603: the decision circuit determines whether the first processing result is greater than zero, and if the first processing result is greater than zero, step 604 is performed; if the first processing result is less than zero, step 605 is performed.

Step 604: and if the output current is determined to be in positive correlation with the first preset alternating current, increasing the direct current bias 1.

Wherein the dc offset 1 corresponds to the first offset dc.

Step 605: and if the output current is determined to be negatively correlated with the first preset alternating current, reducing the direct current bias 1.

Based on the structure of the control circuit, fig. 7 is a schematic flow chart of the implementation of calibrating the resonant wavelength of the ring 2, as shown in fig. 7, including the following steps:

step 701: the differential operation circuit performs differential operation processing on the signal b and the jitter signal 2 respectively to obtain two operation results.

Wherein, the signal b represents that the output current is filtered to obtain a second path of current containing a second frequency; the dither signal 2 represents the second predetermined alternating current.

Step 702: the multiplier multiplies the two operation results to obtain a second processing result.

Step 703: the decision circuit determines whether the second processing result is greater than zero, if so, then step 704 is executed; if the second processing result is less than zero, step 705 is performed.

Step 704: and determining that the output current is in positive correlation with the second preset alternating current, and increasing the direct current bias 2.

Wherein the dc offset 2 represents the second offset dc.

Step 705: determining that the output current is negatively correlated with the second predetermined alternating current and reducing the direct current bias 2.

Based on the control circuit, an embodiment of the present application further provides a control method, applied to the control circuit, as shown in fig. 8, the method includes:

step 801: a photoelectric conversion sub-circuit in the control circuit converts an optical signal output by the double-ring resonator to obtain an output current;

step 802: a signal processing sub-circuit in the control circuit obtains current with preset frequency from the output current; determining an adjustment strategy based on the obtained current;

step 803: and a feedback control sub-circuit in the control circuit adjusts the bias direct current acting on the double-ring resonator micro-ring based on the adjustment strategy so as to lock the resonance wavelength of the double-ring resonator as the central wavelength of the input optical signal.

Based on this, in an embodiment, the optical-to-electrical conversion sub-circuit converts an optical signal output by the double-ring resonator to obtain an output current, and includes: and a photoelectric conversion sub-circuit in the control circuit detects the optical signal output by the double-ring resonator and converts the optical signal to obtain an output current. The optical signal is output by the double-ring resonator after a first current and a second current are respectively applied to two micro-rings of the double-ring resonator; the first current is obtained by superposing a first bias direct current and a first preset alternating current; the second current is obtained by superposing a second bias direct current and a second preset alternating current. The frequency of the first preset alternating current is a first frequency, and the frequency of the second preset alternating current is a second frequency.

Based on this, in one embodiment, the signal processing sub-circuit in the control circuit obtains a current with a preset frequency from the output current; and determining an adjustment strategy based on the obtained current, comprising: a signal processing sub-circuit in the control circuit obtains a first sub-current and a second sub-current by filtering the output current; determining a first adjustment strategy for adjusting the first bias direct current based on the first sub-current; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current.

Based on this, in an embodiment, a feedback control sub-circuit in the control circuit adjusts the bias dc current acting on the dual-ring resonator micro-ring based on the adjustment strategy, including: and a feedback control sub-circuit in the control circuit adjusts the first bias direct current based on the first adjustment strategy, and adjusts the second bias direct current based on the second adjustment strategy, so that the resonance wavelengths of the two micro-rings of the double-ring resonator reach the central wavelength.

Wherein, the micro-ring can be a silicon optical micro-ring. The optical signal output by the double-ring resonator may be obtained by coupling the input optical signal by two micro-rings in the double-ring resonator. Wherein the central wavelength may refer to a central wavelength of an input optical signal of the double-ring resonator.

Here, in practical application, the process of performing fine calibration on the resonant wavelengths of the two micro-rings may be: the output current changes the bias current applied to the two heaters, and further influences the resonant wavelengths of the two micro-rings, so that the coupling optical power of the two micro-rings changes, and further the output current obtained by the photoelectric conversion sub-circuit changes. In order to adjust the bias currents applied to the two heaters by the output current, the output current may be decoupled first to obtain two currents having the same frequency as the corresponding preset alternating current.

Based on this, in an embodiment, a signal processing sub-circuit in the control circuit obtains a first sub-current of the first frequency and a second sub-current of the second frequency by filtering the output current, and includes: based on a first cut-off frequency, filtering the output current to obtain a first sub-current of a first frequency; and based on the second cut-off frequency, filtering the output current to obtain a second sub-current of a second frequency.

Here, the signal processing sub-circuit comprises two filters for filtering the output current; wherein the cut-off frequency of one filter is the first cut-off frequency, and the cut-off frequency of the other filter is the second cut-off frequency. The filter may be a low pass filter, a band pass filter, a high pass filter.

In practical application, the correlation between the output current and the first preset alternating current and the correlation between the output current and the second preset alternating current can be determined by utilizing the two sub-currents obtained by decoupling the output current, the first preset alternating current and the second preset alternating current. The correlation may refer to that the output current is in positive correlation with the first preset alternating current, for example, the output current increases with the increase of the first preset alternating current; the correlation relationship may also mean that the output current is negatively correlated with the first predetermined alternating current, for example, the output current decreases with the increase of the first predetermined alternating current.

Based on this, in an embodiment, the determining, based on the first sub-current, a first adjustment strategy for adjusting the first bias dc; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current, comprising: for each of the first sub-current and the second sub-current, respectively performing differential operation processing on the corresponding current and the corresponding preset alternating current to obtain two operation results, and performing multiplication operation processing on the two operation results to obtain a corresponding processing result; taking the corresponding processing result as a corresponding correlation coefficient of the output current and the corresponding preset alternating current; the corresponding correlation coefficient is used for determining an adjustment strategy for adjusting the corresponding bias direct current.

Based on this, in an embodiment, the determining, based on the obtained corresponding correlation coefficient, an adjustment strategy for adjusting the corresponding bias dc includes: judging whether the corresponding correlation coefficient is larger than a preset threshold value or not to obtain a judgment result; when the judgment result represents that the corresponding correlation coefficient is larger than a preset threshold value, determining that the output current is in positive correlation with the corresponding preset alternating current, and determining an adjustment strategy for increasing the corresponding bias direct current; and when the judgment result indicates that the corresponding correlation coefficient is smaller than a preset threshold value, determining that the output current is in negative correlation with the corresponding preset alternating current, and determining an adjustment strategy for reducing the corresponding bias direct current. Wherein the preset threshold may be zero.

Here, from the coupling efficiency curve diagram shown in fig. 3a, it can be derived that the coupling efficiency gradually increases when the resonance wavelengths of the two micro-rings of the double-ring resonator are adjusted to increase toward the center wavelength; when the resonance wavelengths of the two micro-rings of the double-ring resonator reach the central wavelength, the coupling efficiency reaches the maximum value; when the resonance wavelengths of the two micro-rings of the double-ring resonator are adjusted to be increased towards a direction far away from the central wavelength, the coupling efficiency is gradually reduced. Here, the larger the coupling efficiency is, the larger the optical power output by the double-ring resonator is, the larger the output current obtained by the photoelectric conversion sub-circuit is; the larger the resonant wavelength of the two microrings, the larger the bias current applied to the heater. In other words, when the resonance wavelength of the double-ring resonator is smaller than the center wavelength, the resonance wavelength of the double-ring resonator can be brought closer to the center wavelength by increasing the bias current applied to the heater; when the resonance wavelength of the double-ring resonator is longer than the center wavelength, the resonance wavelength of the double-ring resonator can be closer to the center wavelength by reducing the bias current applied to the heater.

Based on this, in an embodiment, a feedback control sub-circuit in the control circuit adjusts the first bias dc based on the first adjustment strategy and adjusts the second bias dc based on the second adjustment strategy, including: for each preset alternating current of the first preset alternating current and the second preset alternating current, when the output current is in positive correlation with the corresponding preset alternating current, increasing the corresponding bias direct current; and when the output current and the corresponding preset alternating current are in negative correlation, reducing the corresponding bias direct current.

Specifically, when the output current is in positive correlation with the first preset alternating current, the first bias direct current is increased to increase the first current, so that the resonance wavelength of the corresponding micro ring is affected, the coupled optical power of the corresponding micro ring is changed, the output current obtained by the photoelectric conversion sub-circuit is changed, and the optical power output by the double-ring resonator is continuously increased to reach the maximum optical power; when the output current is in negative correlation with the first preset alternating current, the first bias direct current is reduced to reduce the first current, so that the resonant wavelength of the corresponding micro-ring is influenced, the coupling optical power of the corresponding micro-ring is changed, the output current obtained by the photoelectric conversion sub-circuit is changed, and the optical power output by the double-ring resonator is continuously increased to achieve the maximum optical power.

Similarly, when the output current is in positive correlation with the second preset alternating current, the second bias direct current is increased to increase the second current, so that the resonance wavelength of the corresponding micro ring is influenced, the coupled optical power of the corresponding micro ring is changed, the output current obtained by the photoelectric conversion sub-circuit is changed, and the optical power output by the double-ring resonator is continuously increased to reach the maximum optical power; and when the output current is in negative correlation with the second preset alternating current, reducing the second bias direct current to reduce the second current so as to influence the resonant wavelength of the corresponding micro-ring, thereby causing the change of the coupled optical power of the corresponding micro-ring and further causing the change of the output current obtained by the photoelectric conversion sub-circuit, and further causing the optical power output by the double-ring resonator to be continuously increased so as to achieve the maximum optical power.

It should be noted that: "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

The technical means described in the embodiments of the present application may be arbitrarily combined without conflict.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A control circuit, comprising:

2. The circuit of claim 1,

the photoelectric conversion sub-circuit is specifically used for detecting an optical signal output by the double-ring resonator and converting the optical signal to obtain an output current; the optical signal is output by the double-ring resonator after a first current and a second current are respectively applied to two micro-rings of the double-ring resonator; the first current is obtained by superposing a first bias direct current and a first preset alternating current; the second current is obtained by superposing a second bias direct current and a second preset alternating current; the frequency of the first preset alternating current is a first frequency, and the frequency of the second preset alternating current is a second frequency.

3. The circuit of claim 2, wherein the signal processing sub-circuit is configured to obtain a first sub-current of the first frequency and a second sub-current of the second frequency by filtering the output current; determining a first adjustment strategy for adjusting the first bias direct current based on the first sub-current; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current.

4. The circuit according to claim 3, wherein the feedback control sub-circuit is configured to adjust the first bias dc based on the first adjustment strategy and to adjust the second bias dc based on the second adjustment strategy, such that the resonant wavelengths of both micro-rings of the dual-ring resonator reach the center wavelength.

5. The circuit according to claim 3 or 4, wherein the signal processing sub-circuit is specifically configured to:

based on a first cut-off frequency, filtering the output current to obtain a first sub-current of the first frequency; and based on a second cut-off frequency, filtering the output current to obtain a second sub-current of the second frequency.

6. The circuit of claim 5, wherein the signal processing sub-circuit comprises two filters for filtering the output current; wherein the cut-off frequency of one filter is the first cut-off frequency, and the cut-off frequency of the other filter is the second cut-off frequency.

7. The circuit of claim 6, wherein the signal processing sub-circuit further comprises a differential operation circuit;

8. The circuit of claim 7, wherein the signal processing sub-circuit is specifically configured to:

judging whether the corresponding correlation coefficient is larger than a preset threshold value or not to obtain a judgment result; when the judgment result represents that the corresponding correlation coefficient is larger than a preset threshold value, determining that the output current is in positive correlation with the corresponding preset alternating current, and determining an adjustment strategy for increasing the corresponding bias direct current; and when the judgment result represents that the corresponding correlation coefficient is smaller than a preset threshold value, determining that the output current is in negative correlation with the corresponding preset alternating current, and determining an adjustment strategy for reducing the corresponding bias direct current.

9. The circuit of claim 2, wherein the feedback control sub-circuit is specifically configured to:

for each preset alternating current of the first preset alternating current and the second preset alternating current, increasing the corresponding bias direct current when the output current is in positive correlation with the corresponding preset alternating current; and when the output current and the corresponding preset alternating current are in negative correlation, reducing the corresponding bias direct current.

10. A control method is applied to a control circuit and comprises the following steps:

converting an optical signal output by the double-ring resonator to obtain an output current;

11. The method of claim 10, wherein converting the optical signal output by the double-ring resonator to obtain the output current comprises:

detecting an optical signal output by the double-ring resonator, and converting the optical signal to obtain an output current; the optical signal is output by the double-ring resonator after a first current and a second current are respectively applied to two micro-rings of the double-ring resonator; the first current is obtained by superposing a first bias direct current and a first preset alternating current; the second current is obtained by superposing a second bias direct current and a second preset alternating current; the frequency of the first preset alternating current is a first frequency, and the frequency of the second preset alternating current is a second frequency.

12. The method of claim 11, wherein the current of a preset frequency is obtained from the output current; and determining an adjustment strategy based on the obtained current, comprising:

filtering the output current to obtain a first sub-current of the first frequency and a second sub-current of the second frequency; determining a first adjustment strategy for adjusting the first bias direct current based on the first sub-current; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current.

13. The method of claim 12, wherein the adjusting the bias dc current applied to the micro-ring of the dual-ring resonator based on the adjustment strategy to lock the resonant wavelength of the dual-ring resonator to the center wavelength of the input optical signal comprises:

and adjusting the first bias direct current based on the first adjustment strategy, and adjusting the second bias direct current based on the second adjustment strategy, so that the resonance wavelengths of the two micro-rings of the double-ring resonator reach the central wavelength.

14. The method according to claim 12 or 13, wherein the obtaining the first sub-current of the first frequency and the second sub-current of the second frequency by filtering the output current comprises:

15. The method according to claim 12 or 13, wherein the determining of a first adjustment strategy for adjusting the first bias dc is based on the first sub-current; and determining a second adjustment strategy for adjusting the second bias direct current based on the second sub-current, comprising:

for each of the first sub-current and the second sub-current, respectively performing differential operation processing on the corresponding sub-current and the corresponding preset alternating current to obtain two operation results, and performing multiplication operation processing on the two operation results to obtain a corresponding processing result; taking the corresponding processing result as a corresponding correlation coefficient of the output current and the corresponding preset alternating current; and determining an adjusting strategy for adjusting the corresponding bias direct current based on the obtained corresponding correlation coefficient.

16. The method of claim 15, wherein determining an adjustment strategy for adjusting the respective bias dc based on the obtained respective correlation coefficients comprises:

judging whether the corresponding correlation coefficient is larger than a preset threshold value or not to obtain a judgment result; when the judgment result indicates that the corresponding correlation coefficient is larger than a preset threshold value, determining that the output current is in positive correlation with the corresponding preset alternating current, and determining an adjustment strategy for increasing the corresponding bias direct current; and when the judgment result represents that the corresponding correlation coefficient is smaller than a preset threshold value, determining that the output current is in negative correlation with the corresponding preset alternating current, and determining an adjustment strategy for reducing the corresponding bias direct current.

17. The method of claim 11, wherein the adjusting a bias direct current applied to the dual-ring resonator micro-ring based on the adjustment strategy comprises: