CN115039052A

CN115039052A - Bias voltage adjusting method and device and optical module

Info

Publication number: CN115039052A
Application number: CN202080095292.5A
Authority: CN
Inventors: 齐鸣
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2022-09-09
Anticipated expiration: 2040-03-13
Also published as: CN115039052B; WO2021179318A1

Abstract

A bias voltage adjusting method, a bias voltage adjusting device and an optical module are provided, wherein a controller (13) controls a bias circuit (12) to provide bias voltage for an APD (11; 22), when an optical signal is applied to the APD (11; 22), the APD (11; 22) generates photocurrent by the optical signal under the action of the bias voltage, and the controller (13) acquires the current value of the photocurrent and controls the bias circuit to dynamically adjust the bias voltage according to the current value. In the process, the magnitude of the photocurrent is influenced by the optical power of the optical signal, the magnitude of the bias voltage and the like, so the bias voltage adjusting device (200; 300) can ensure the real-time control of the bias voltage of the APD (11; 22) by dynamically controlling the magnitude of the bias voltage, and avoid the damage of the APD (11; 22) due to the generation of the overlarge photocurrent.

Description

Bias voltage adjusting method and device and optical module

Technical Field

The embodiment of the application relates to the technical field of optical fiber communication, in particular to a bias voltage adjusting method and device and an optical module.

Background

With the rapid development of optical fiber communication technology, the application scenario of an optical module, which is an important component in optical fiber communication, becomes more and more complex, and the requirement of a user on the optical parameter index of the optical module, especially the Sensitivity (SEN) of the optical module, also becomes higher and higher.

The sensitivity of the optical module refers to the minimum optical power that the optical receiving circuit in the optical module is allowed to receive. It should be understood that, in the transmission process of the optical signal, the longer the transmission distance, the greater the optical power loss, and the longer the transmission distance, the higher the requirement for sensitivity. Optical modules typically use Avalanche Photodiodes (APDs) to increase sensitivity to extend transmission distances. To optimize the sensitivity of the optical module, the controller in the optical module typically sets the bias voltage of the APD to be relatively high, close to the avalanche voltage of the APD. At this time, the multiplication factor of the APD is large, and a large photocurrent can be obtained with a small optical power.

However, there is an upper limit to the received optical power of the APD, and when the optical power input to the APD is large, the APD generates a large photocurrent, which flows through the APD and may damage the APD. Therefore, how to make the sensitivity of the optical module high without damaging the APD is a problem to be solved urgently.

Disclosure of Invention

The embodiment of the application provides a bias voltage adjusting method, a bias voltage adjusting device and an optical module, wherein the bias voltage provided by a bias circuit for an APD is adjusted by detecting the magnitude of a photocurrent of the APD, so that the APD does not generate an excessive photocurrent, and the purpose of protecting the APD is achieved.

In a first aspect, an embodiment of the present application provides a bias voltage adjusting method, which may be applied to a bias voltage adjusting device, where the bias voltage adjusting device may be independently arranged or integrated on an optical module. When the method is applied to an optical module, the method may be a chip in the optical module or the like. The method is described below by taking the application to the terminal device as an example, and the method includes: the controller controls the bias circuit to provide bias voltage for the APD, when an optical signal is applied to the APD, the APD generates a photocurrent under the action of the bias voltage by using the optical signal, acquires the current value of the photocurrent, and controls the bias circuit to dynamically adjust the bias voltage according to the current value. In this process, because the magnitude of the photocurrent is affected by the optical power of the optical signal and the magnitude of the bias voltage, the bias voltage adjusting device provided in the embodiment of the present application can ensure real-time control of the bias voltage of the APD by dynamically controlling the magnitude of the bias voltage, and prevent the APD from generating an excessive photocurrent and being damaged.

In one possible design, when controlling the bias circuit to dynamically adjust the bias voltage according to the current value, the controller determines whether the current value exceeds a first threshold, where the first threshold is used to indicate a minimum current value of a photocurrent generated when the APD is broken down; when the current value exceeds a first threshold, reducing the bias voltage to make the APD incapable of working; when the current value does not exceed the first threshold, the bias voltage is raised such that the bias voltage approaches an avalanche voltage of the APD. By adopting the scheme, when the optical power of the optical signal irradiated on the APD is identified to be overlarge according to the current value, the bias voltage is reduced to protect the APD, and when the optical power of the optical signal irradiated on the APD is identified to be normal according to the current value, the bias voltage is improved to ensure the optimal working effect of the APD.

In one possible design, the controller determines whether the current value exceeds a second threshold indicating a minimum current value for distinguishing whether the APD is illuminated by the optical signal before determining whether the current value exceeds the first threshold. By adopting the scheme, the controller adjusts the bias voltage only when the optical signal irradiates on the APD, and the calculation amount of the controller is reduced.

In one possible design, the bias voltage output by the control bias circuit remains unchanged when the current value does not exceed the second threshold. By adopting the scheme, the controller adjusts the bias voltage only when the optical signal irradiates on the APD, and the calculation amount of the controller is reduced.

In a feasible design, before the controller controls the bias circuit to dynamically adjust the bias voltage according to the current value, the controller also controls the bias circuit to output the bias voltage which changes periodically according to detection periods, each detection period comprises a first interval and a second interval, the first bias voltage of the first interval is higher than the second bias voltage of the second interval, the first bias voltage is smaller than the avalanche voltage of the APD and ensures the APD to work, the second bias voltage enables the APD not to work, and the detection period is used for indicating the period of the photocurrent detection module for detecting the current value. By adopting the scheme, the controller has enough time to adjust the bias voltage because each detection period has a second interval, thereby reducing the hardware requirement.

In one possible design, the controller controls the bias circuit to dynamically adjust the first bias voltage according to the current value while controlling the bias circuit to dynamically adjust the bias voltage according to the current value. By adopting the scheme, the controller only needs to adjust the first bias voltage of the first interval in the detection period, and the mode is simple.

In a feasible design, when the controller controls the bias circuit to dynamically adjust the first bias voltage according to the current value, and when the current value of the photocurrent generated by the APD in the ith detection period exceeds a first threshold, the first bias voltage is reduced, so that the APD cannot work in a first interval of an (i + 1) th detection period, and the ith detection period are any two adjacent detection periods. By adopting the scheme, the purpose of periodically adjusting the bias voltage according to detection is realized.

In one possible design, the second bias voltage is greater than or equal to 0 volts.

In one possible design, the first bias voltage output by the bias circuit in the first interval of the i-th detection period and the second bias voltage output by the bias circuit in the second interval form any one of the following waveforms: square wave, sine wave, triangular wave, irregular wave. By adopting the scheme, the purpose of flexibly setting the bias voltage in each detection period is realized.

In one possible design, the duration of the first interval is less than a first duration, and the first duration is used to indicate a maximum duration that the APD is not damaged at the first bias voltage and at the maximum optical power; the duration of the second interval is greater than a second duration, and the second duration is used for indicating the response duration of starting the APD. By adopting the scheme, the purpose of accurately determining the time length of the first interval and the second interval in one detection period is achieved.

In a second aspect, an embodiment of the present application provides a bias voltage adjusting apparatus, including:

a bias circuit for providing a bias voltage;

an Avalanche Photodiode (APD) for generating a photocurrent by an optical signal under the action of the bias voltage;

a photocurrent detection circuit for detecting the photocurrent to obtain a current value;

and the controller is respectively coupled to the bias circuit and the photocurrent detection circuit and is used for controlling the bias circuit to adaptively adjust the bias voltage according to the current value.

In one possible design, the controller is specifically configured to determine whether the current value exceeds a first threshold, where the first threshold is used to indicate a minimum current value of a photocurrent generated when the APD is broken down, and when the current value exceeds the first threshold, reduce the bias voltage to disable the APD; when the current value does not exceed a first threshold, raising the bias voltage such that the bias voltage approximates an avalanche voltage of the APD, thereby causing the APD to operate normally.

In one possible design, the controller is further configured to determine that the current value exceeds a second threshold before determining whether the current value exceeds the first threshold, the second threshold being configured to indicate a minimum current value for distinguishing whether an optical signal is incident on the APD.

In a possible design, the controller is further configured to control the bias voltage output by the bias circuit to remain unchanged when the current value does not exceed the second threshold.

In a possible design, the controller is further configured to control the bias circuit to output a periodically varying bias voltage according to detection periods before controlling the bias circuit to dynamically adjust the bias voltage according to the current value, where each of the detection periods includes a first interval and a second interval, a first bias voltage of the first interval is higher than a second bias voltage of the second interval, the first bias voltage is smaller than an avalanche voltage of the APD and ensures that the APD operates, the second bias voltage disables the APD, and the detection period is used to instruct the photocurrent detection module to detect a period of the current value.

In one possible design, the controller is specifically configured to control the bias circuit to dynamically adjust the first bias voltage according to the current value.

In a possible design, the controller is specifically configured to decrease the first bias voltage when a current value of a photocurrent generated by the APD in an i-th detection period exceeds the first threshold, so that the APD cannot operate in a first interval of the i + 1-th detection period, where the i-th detection period and the i-th detection period are any two adjacent detection periods.

In one possible design, the first bias voltage output by the bias circuit in the first interval of the i-th detection period and the second bias voltage output by the bias circuit in the second interval form any one of the following waveforms: square wave, sine wave, triangular wave, irregular wave.

In one possible design, the duration of the first interval is less than a first duration, the first duration indicating a maximum duration that the APD is not damaged when under the first bias voltage and subject to a maximum optical power;

and the duration of the second interval is greater than a second duration, and the second duration is used for indicating the response duration of APD starting.

In a third aspect, an embodiment of the present application provides a bias voltage adjusting apparatus, including:

a bias voltage output unit for outputting a bias voltage;

a photocurrent detection unit for detecting the photocurrent to obtain a current value;

and the processing unit is used for adjusting the bias voltage according to the current value.

In a possible design, the processing unit is specifically configured to determine whether the current value exceeds a first threshold, where the first threshold is used to indicate a minimum current value of a photocurrent generated when the APD is broken down, and when the current value exceeds the first threshold, reduce the bias voltage, so that the APD cannot operate; when the current value does not exceed a first threshold, raising the bias voltage such that the bias voltage approximates an avalanche voltage of the APD, thereby causing the APD to operate normally.

In one possible design, the processing unit, before determining whether the current value exceeds a first threshold, is further configured to determine that the current value exceeds a second threshold, where the second threshold is used to indicate a minimum current value for distinguishing whether an optical signal is incident on the APD.

In a possible design, the processing unit is further configured to control the bias voltage output by the bias voltage output unit to remain unchanged when the current value does not exceed the second threshold.

In a possible design, before controlling the bias voltage output unit to dynamically adjust the bias voltage according to the current value, the processing unit is further configured to control the bias voltage output unit to output a periodically varying bias voltage according to detection periods, where each of the detection periods includes a first interval and a second interval, a first bias voltage in the first interval is higher than a second bias voltage in the second interval, the first bias voltage is lower than an avalanche voltage of the APD and ensures that the APD operates, the second bias voltage disables the APD, and the detection period is used to instruct the photocurrent detection module to detect a period of the current value.

In a possible design, the processing unit is specifically configured to control the bias voltage output unit to dynamically adjust the first bias voltage according to the current value.

In a possible design, the processing unit is specifically configured to decrease the first bias voltage when a current value of a photocurrent generated by the APD in an i-th detection period exceeds the first threshold, so that the APD cannot operate in a first interval of the i + 1-th detection period, where the i-th detection period and the i-th detection period are any two adjacent detection periods.

In a possible design, the first bias voltage output by the bias voltage output unit in the first interval of the i-th detection period and the second bias voltage output by the second interval form any one of the following waveforms: square wave, sine wave, triangular wave, irregular wave.

In one possible design, the duration of the first interval is less than a first duration, the first duration indicating a maximum duration that the APD is not damaged when under the first bias voltage and subject to a maximum optical power; the duration of the second interval is greater than a second duration, and the second duration is used for indicating the response duration of starting the APD.

In a fourth aspect, an embodiment of the present application provides an optical module, including a bias voltage adjusting apparatus implemented as the second aspect or in various possible implementations of the second aspect; alternatively, the bias voltage adjusting apparatus implemented in the third aspect or various possible implementations of the third aspect is included.

In a fifth aspect, embodiments of the present application provide a bias voltage adjusting apparatus, which includes a processor, a memory, and a computer program stored on the memory and executable on the processor, and the processor executes the program to enable the bias voltage adjusting apparatus to implement the method according to the first aspect or the various possible implementation manners of the first aspect.

In a sixth aspect, an embodiment of the present application provides a bias voltage adjusting apparatus, including: the data processing device comprises a logic circuit and an input interface, wherein the input interface is used for acquiring data to be processed, and the logic circuit is used for executing the method of any one of the first aspect on the data to be processed to obtain the processed data.

In one possible design, the bias voltage adjusting apparatus further includes: an output interface for outputting the processed data.

In a seventh aspect, an embodiment of the present application provides a computer-readable storage medium for storing a program, where the program is used to execute the method of any one of the first aspect when the program is executed by a processor.

In an eighth aspect, embodiments of the present application provide a computer program product, which when run on a bias voltage adjusting apparatus, causes the bias voltage adjusting apparatus to perform the method of any one of the first aspects.

According to the bias voltage adjusting method, the bias voltage adjusting device and the optical module, the controller controls the bias circuit to provide bias voltage for the APD, when an optical signal is applied to the APD, the APD generates photocurrent under the action of the bias voltage by using the optical signal, the controller obtains the current value of the photocurrent, and controls the bias circuit to dynamically adjust the bias voltage according to the current value. In this process, because the magnitude of the photocurrent is affected by the optical power of the optical signal and the magnitude of the bias voltage, the bias voltage adjusting device provided in the embodiment of the present application can ensure real-time control of the bias voltage of the APD by dynamically controlling the magnitude of the bias voltage, and prevent the APD from generating an excessive photocurrent and being damaged.

Drawings

Fig. 1 is a circuit diagram of a protection circuit for protecting an APD by providing a current limiting resistor;

FIG. 2A is a schematic diagram of a bias voltage adjusting apparatus according to an embodiment of the present disclosure;

FIG. 2B is a flow chart of a bias voltage adjustment method provided by an embodiment of the present application;

FIG. 3A is a schematic diagram of bias voltage adjustment provided by an embodiment of the present application;

FIG. 3B is a schematic diagram of another bias voltage adjustment provided by embodiments of the present application;

FIG. 3C is a schematic diagram of yet another bias voltage adjustment provided by an embodiment of the present application;

FIG. 4A is a waveform diagram of a bias voltage in a bias voltage adjusting method according to an embodiment of the present disclosure;

FIG. 4B is a waveform diagram of another bias voltage in the bias voltage adjustment method provided by the embodiment of the present application;

FIG. 4C is a waveform diagram of a bias voltage according to another bias voltage adjusting method provided by the embodiment of the present application;

FIG. 4D is a waveform diagram of a further bias voltage in the bias voltage adjustment method according to the embodiment of the present application;

FIG. 5A is a schematic diagram of a bias voltage adjustment method according to an embodiment of the present disclosure;

FIG. 5B is a schematic diagram of another bias voltage adjustment method provided by an embodiment of the present application;

FIG. 5C is a schematic diagram of another bias voltage adjustment method provided by an embodiment of the present application;

FIG. 6 is a flow chart of a bias voltage adjustment method provided by an embodiment of the present application;

fig. 7 is a schematic diagram of linear increase of optical power in the method for protecting ADP provided by the embodiment of the application;

FIG. 8 is a schematic diagram of another bias voltage adjustment apparatus provided in an embodiment of the present application;

fig. 9 is a schematic diagram of another bias voltage adjusting apparatus provided in the embodiment of the present application.

Detailed Description

At present, APD is a common receiver in optical modules, which may be called as APD receiver or APD receiver, and usually the bias voltage of APD is set near the avalanche voltage to make the sensitivity of APD higher. The APD generates a photocurrent using a received optical signal under a bias voltage provided by a bias circuit. However, the APD has an upper limit of the optical power of an optical signal that can be received at a certain bias voltage, and if the optical power exceeds the upper limit, the APD generates a large photocurrent, and the large photocurrent flows through the APD, which causes damage to the APD. In general, an optical signal that can cause damage to an APD is referred to as large light, and an optical signal that can cause the APD to operate normally is referred to as normal light. In order to protect the APD, a common APD protection circuit is to provide a current limiting resistor. For example, referring to fig. 1, fig. 1 is a circuit diagram of a protection circuit for protecting an APD by providing a current limiting resistor.

Referring to fig. 1, in the protection circuit, a current limiting resistor is serially connected between an output terminal of the bias circuit and an input terminal of the APD, and the output terminal of the APD is coupled to a trans-impedance amplifier (TIA). When the bias voltage is constant, the optical power of the optical signal irradiated on the APD is too large, so that when the APD generates too large photocurrent, the large current flows through the current-limiting resistor to generate certain voltage drop, the voltage on the APD is reduced, and the purpose of protecting the APD is achieved.

However, in the prior art, there are several models of APDs, and the resistance values of the current limiting resistors required by different models of APDs are different, so that it is difficult to accurately select the current limiting resistor. If the resistance value of the current-limiting resistor is too small, the limited current is less, and the purpose of protecting APD cannot be realized; if the resistance value of the current-limiting resistor is too large, the limited current is too much, and the performance of the APD under normal optical power, such as an overload point, sensitivity and the like, is influenced.

In view of this, embodiments of the present application provide a bias voltage adjusting method, a bias voltage adjusting device, and an optical module, which adjust a bias voltage provided by a bias circuit to an APD by detecting a magnitude of a photocurrent of the APD, so that the APD does not generate an excessive photocurrent, and the purpose of protecting the APD is achieved.

Fig. 2A is a schematic diagram of a bias voltage adjusting apparatus according to an embodiment of the present disclosure. Referring to fig. 2A, the bias voltage adjusting apparatus 100 includes: an avalanche photodiode APD11, a bias circuit 12, a controller 13, and a photocurrent detection circuit 14, an input of the bias circuit 12 being coupled to the controller 13, an output of the bias circuit 12 being coupled to an input of the APD11, an output of the APD11 being coupled to an input of the photocurrent detection circuit 14, an output of the photocurrent detection circuit 14 being coupled to the controller 13.

The working principle of the bias voltage regulating device is as follows: the APD11 is used for generating a photocurrent by using the received optical signal under the action of a bias voltage provided by the bias circuit 12;

a bias circuit 12 for providing a bias voltage to the APD11, the magnitude of the bias voltage being controlled by the controller 13;

and the controller 13 is configured to control the bias circuit 12 to dynamically adjust the magnitude of the bias voltage according to the magnitude of the current value of the photocurrent fed back by the photocurrent detection circuit 14. The controller 13 is an Integrated Circuit chip with data Processing capability, and may be a general-purpose Central Processing Unit (CPU), a microprocessor, an Application Specific Integrated Circuit (ASIC), or the like.

The bias voltage adjusting device provided by the embodiment of the application comprises an APD, a bias voltage circuit, a controller and a photocurrent detection circuit, wherein the input end of the bias voltage circuit is coupled with the controller, the output end of the bias voltage circuit is coupled with the input end of the APD, the output end of the APD is coupled with the input end of the photocurrent detection circuit, and the output end of the photocurrent detection circuit is coupled with the controller, so that a closed-loop feedback control loop is formed. Because the magnitude of the photocurrent is affected by the optical power of the optical signal, the magnitude of the bias voltage, and the like, the bias voltage adjusting device provided by the embodiment of the application can ensure the real-time control of the bias voltage of the APD by dynamically controlling the magnitude of the bias voltage, and avoid the APD from generating excessive photocurrent to be damaged.

An optical module is further provided in an embodiment of the present application, and includes the foregoing bias voltage adjusting device, for which reference is specifically made to the descriptions of the foregoing bias voltage adjusting device and the bias voltage adjusting method, which are not described herein again.

The embodiment of the application also provides a bias voltage adjusting method on the basis of the bias voltage adjusting device. Next, the method is described in detail, for example, referring to fig. 2B, where fig. 2B is a flowchart of a bias voltage adjusting method provided in an embodiment of the present application, an execution subject of the embodiment is, for example, a controller, and the embodiment includes the following steps:

101. the current value of the photocurrent generated by the avalanche photodiode APD using the optical signal under the bias voltage provided by the bias circuit is acquired.

Illustratively, the controller controls the bias circuit to provide a bias voltage for the APD, when an optical signal is incident on the APD, the APD generates a photocurrent by the optical signal under the bias voltage, and the controller obtains a current value of the photocurrent.

102. And controlling the bias circuit to dynamically adjust the bias voltage according to the current value.

For example, after obtaining the current value of the APD, the controller controls the bias circuit to dynamically adjust the bias voltage, such as increasing the bias voltage, decreasing the bias voltage, and the like, by using the current value.

In the bias voltage adjusting method provided by the embodiment of the application, the controller controls the bias circuit to provide bias voltage for the APD, when an optical signal is applied to the APD, the APD generates photocurrent under the action of the bias voltage by using the optical signal, and the controller acquires the current value of the photocurrent and controls the bias circuit to dynamically adjust the bias voltage according to the current value. In this process, because the magnitude of the photocurrent is affected by the optical power of the optical signal and the magnitude of the bias voltage, the bias voltage adjusting device provided in the embodiment of the present application can ensure real-time control of the bias voltage of the APD by dynamically controlling the magnitude of the bias voltage, and prevent the APD from generating an excessive photocurrent and being damaged.

In the above embodiment, when no optical signal is irradiated on the APD, the controller controls the bias circuit to provide an initial bias voltage to the APD, where the bias voltage is smaller than the avalanche voltage and can ensure that the optical signal is irradiated on the APD, and the APD can operate. In the process of adjusting the bias voltage, when an optical signal irradiates on the APD, so that the APD generates a photocurrent under the bias voltage provided by the bias circuit, the controller controls the bias circuit to dynamically adjust the magnitude of the bias voltage according to the current value of the photocurrent. For example, referring to fig. 3A-3C, fig. 3A is a schematic diagram of a bias voltage adjustment provided by an embodiment of the present application; FIG. 3B is a schematic diagram of another bias voltage adjustment provided by embodiments of the present application; fig. 3C is a schematic diagram of another bias voltage adjustment provided by the embodiment of the present application.

Scene one, scene without light to high light.

In the embodiments of the present application, an optical signal that can cause damage to an APD is referred to as a large light. When the power of the optical signal provided by the optical signal source is too high, if the optical signal is turned on, such as turning on a laser or inserting an optical fiber, the APD generates too large photocurrent.

Referring to fig. 3A, after the bias voltage adjusting device is activated, if the optical power of the optical signal is too low or even no optical signal is irradiated on the APD, for example, the laser is not turned on and the optical fiber is not inserted, the bias circuit continuously provides a bias voltage to the APD, where the bias voltage is smaller than the avalanche voltage and can ensure that the optical signal is irradiated on the APD, and the APD can operate. An APD generates a photocurrent when an optical signal impinges thereon. The controller judges whether the photocurrent exceeds a first threshold, wherein the first threshold is used for indicating the minimum current value of the photocurrent generated when the APD is broken down, the first threshold is a parameter which substantially distinguishes whether an optical signal is normal light or large light, and if the current value of the APD exceeds the first threshold, the controller considers that the optical power of the optical signal irradiated on the APD exceeds the range which can be borne by the APD, namely the optical signal is large light; otherwise, the controller considers the optical power of the optical signal illuminated on the APD to be within the range that the APD can tolerate, i.e., the optical signal is a normal light.

The avalanche breakdown refers to breakdown of the APD due to excessive optical power of an optical signal or the like at an avalanche voltage, and here refers to breakdown of the APD due to excessive optical power of the optical signal at an initial bias voltage. Obviously, the first threshold is smaller than the current value at avalanche breakdown.

When the APD generates the photocurrent, if the current value of the photocurrent exceeds the first threshold, it indicates that the optical power of the optical signal is too high, and therefore, the controller controls the bias circuit to reduce the bias voltage, and the reduced bias voltage makes the APD unable to operate, even if the aforementioned optical signal irradiates on the APD, the APD is unable to operate. The reduced bias voltage is, for example, 0 volt or close to 0 volt, etc., and the embodiments of the present application are not limited thereto.

By adopting the scheme, the purposes of identifying large optical signals and protecting APDs by the APDs are achieved.

Scene two, scene without light to normal light.

In the embodiment of the present application, an optical signal whose bias voltage is close to the avalanche voltage and which can ensure that the APD is not damaged is referred to as normal light. When the optical signal source can provide normal light, if the optical signal is turned on, such as turning on a laser or inserting an optical fiber, the APD is enabled to generate normal photocurrent. The approaching avalanche voltage means that the difference between the bias voltage and the avalanche voltage is smaller than a preset value.

Referring to fig. 3B, when the APD generates the photocurrent, if the current value of the photocurrent does not exceed the first threshold, it is indicated that the optical power of the optical signal can prevent the APD from being broken down, and therefore, the controller controls the bias circuit to increase the bias voltage so as to enable the bias voltage to approach the avalanche voltage of the APD, and then the controller controls the bias circuit to continuously output the bias voltage approaching the avalanche voltage so as to enable the APD to normally operate.

By adopting the scheme, the aim of identifying normal optical signals by the APD is fulfilled.

Scene three, no light scene.

In the embodiment of the present application, when the laser is not turned on, the optical fiber is not inserted, or the optical power of the optical signal is too small, a scene in which the APD cannot generate the optical photocurrent is referred to as a no-light scene.

Referring to fig. 3C, in a scene without light, the controller controls the bias circuit to always output an initial bias voltage, and since no light signal is irradiated on the APD, the APD cannot generate a photocurrent, at this time, the current value detected by the current detection circuit is 0, and the controller determines that the current value does not exceed the second threshold, and then keeps the bias voltage output by the bias circuit unchanged. Wherein the second threshold is used for indicating the current value of the minimum photocurrent generated by the APD, the second threshold is a parameter which substantially distinguishes that no optical signal irradiates on the APD, and if the current value of the APD exceeds the second threshold, the APD is considered to have the optical signal irradiate on the APD; otherwise, the controller deems that no optical signal is impinging on the APD.

By adopting the scheme, the aim of identifying the lightless scene by the APD is fulfilled.

In both fig. 3A and fig. 3B, the bias voltage provided by the bias voltage before the bias voltage is adjusted is not changed. However, the embodiment of the present application is not limited to this, in other possible implementations, the bias circuit may output a bias voltage that varies periodically according to detection periods, where each of the detection periods includes a first interval and a second interval, a first bias voltage of the first interval is higher than a second bias voltage of the second interval, the first bias voltage is smaller than an avalanche voltage of the APD and ensures that the APD operates, the second bias voltage disables the APD, and the detection period is used to instruct the photocurrent detection module to detect a period of the current value. For example, please refer to fig. 4A-4D. FIG. 4A is a waveform diagram of a bias voltage in a bias voltage adjusting method according to an embodiment of the present disclosure; FIG. 4B is a waveform diagram of another bias voltage in the bias voltage adjusting method according to the embodiment of the present application; FIG. 4C is a waveform diagram of a further bias voltage in the bias voltage adjusting method according to the embodiment of the present application; fig. 4D is a waveform diagram of another bias voltage in the bias voltage adjusting method according to the embodiment of the present application.

Referring to fig. 4A, in a detection period, the waveform of the bias voltage output by the bias circuit is a square wave, and at this time, the first bias voltage is a specific value and the second bias voltage is a specific value. The first bias voltage is different and the second bias voltage may be different for different models of APDs. For example, assuming that the avalanche voltage of a certain model of APD is 30 volts (V), the first bias voltage is 10V and the second bias voltage is 1V.

Referring to fig. 4B, in a detection period, the waveform of the bias voltage output by the bias circuit is a sine wave, and at this time, the first bias voltage is a voltage interval, and the second bias voltage is a voltage interval. For APDs of different models, the voltage intervals corresponding to the first bias voltage are different, and the voltage intervals corresponding to the second bias voltage may also be different. For example, if the avalanche voltage of an APD of a certain type is 30 volts (V), the first bias voltage is 8V to 10V, the second bias voltage is 0V to 1V, and the value of the second bias voltage is only required to ensure that the APD cannot be turned on, and is not required to be set to 0V. By adopting the scheme, the purpose of flexibly setting the second bias voltage is realized.

Referring to fig. 4C, in a detection period, the waveform of the bias voltage output by the bias circuit is a triangular wave, and at this time, the first bias voltage is a voltage interval and the second bias voltage is a voltage interval.

Referring to fig. 4D, in a detection period, the waveform of the bias voltage output by the bias circuit is an irregular waveform, and at this time, the first bias voltage is a voltage interval, and the second bias voltage is a voltage interval.

By adopting the scheme, the aim of flexibly setting the periodically output bias voltage is fulfilled.

In the embodiment of the present application, there are at least three reasons for APD damage: the bias voltage, the optical power of the optical signal, and the length of time that the APD is capable of producing a photocurrent. The fact that the excessive photocurrent generated by the APD under a certain bias voltage and a certain optical signal can damage the APD means that the duration of the photocurrent flowing through the APD is longer than the maximum duration of the photocurrent that the APD can bear under the bias voltage and the optical signal. Therefore, in the above-mentioned fig. 4A-4D, the duration of the first interval and the duration of the second interval are related to the model of the APD, and the duration of the first interval is different or the same for APDs of different models, and the duration of the second interval may also be the same or different. The duration of the first interval is a first duration, the first duration is used for indicating the maximum duration that the APD is not damaged under the first bias voltage and bears the maximum optical power, the duration of the second interval is longer than a second duration, and the second duration is used for indicating the response duration of starting the APD. For example, when the optical signal is large light, the photocurrent generated by a certain type of APD under the bias voltage lasts for 600 milliseconds, and the APD is damaged, but the APD is not damaged within 600 milliseconds, that is, the duration of the large optical power that the APD can bear without being damaged is 600 milliseconds, and the duration of the first interval may be 500 milliseconds, and the like; assuming that the duration of time required for the APD from normal optical signal input to normal start-up is 400 msec, the duration of the second interval may be set to 800 msec. It will be appreciated that the duration of the first and second intervals may also take into account the duration of the response of the controller, etc.

By adopting the scheme, the purpose of determining the duration of the first interval and the second interval of the detection period is realized.

It should be noted that the waveforms in fig. 4A to 4D refer to waveforms of bias voltages in a scenario where the optical signal source is not turned on or the optical power provided by the optical signal source is too small to enable the APD to generate a photocurrent.

In the following, taking the waveform of the bias voltage as a square wave as an example, the above-mentioned first, second and third scenarios will be described in detail as to how the controller controls the bias circuit to output the periodic bias voltage. For example, referring to fig. 5A to 5C, fig. 5A is a schematic diagram of a bias voltage adjusting method provided by an embodiment of the present application; FIG. 5B is a schematic diagram of another bias voltage adjustment method provided by an embodiment of the present application; fig. 5C is a schematic diagram of another bias voltage adjustment method provided in the embodiment of the present application.

Scene one': no light to a high light scene.

Referring to fig. 5A, after the bias voltage adjusting device is started, if the optical power of the optical signal is too low or no optical signal is applied to the APD in a plurality of periods before the ith detection period, such as the ith-1 detection period, the ith-2 detection period, and the like, if the laser is not turned on and the optical fiber is not inserted, the bias circuit periodically outputs the bias voltage, and the APD cannot normally operate during the period.

Assuming that the ith detection cycle begins, the laser is turned on or fiber insertion begins to provide an optical signal to the APD; moreover, for a certain type of APD device, the optical signal is a large light. At this time, the APD outputs a first bias voltage in a first interval of the ith detection period, and the APD generates a photocurrent, which is greater than a current value and greater than a first threshold, by using the high voltage, and the photocurrent is fed back to the controller by the photocurrent detection circuit. After the controller receives the feedback, the first bias voltage is reduced and output in the first interval, and the second bias voltage output in the second interval is kept unchanged. If the optical signal keeps a large optical state from the i +1 th detection period, the waveform of the bias voltage keeps the waveform in the i +1 th detection period. Moreover, from the i +1 th detection period, the APD cannot operate normally. By adopting the scheme, the purpose of identifying scenes from no light to large light by the APD is realized.

Although the photocurrent generated by the APD is large in the first interval of the (i + 1) th detection period, the APD can be prevented from being damaged because the length of the (i + 1) th first interval is short.

Scene two': there is no light to normal light scenes.

Referring to fig. 5B, after the bias voltage adjusting device is started, if the optical power of the optical signal is too low or no optical signal irradiates on the APD for a plurality of periods before the ith detection period, such as the ith-1 detection period, the ith-2 detection period, and the like, if the laser is not turned on and the optical fiber is not inserted, the bias circuit periodically outputs the bias voltage, and the APD cannot normally operate during the period.

Assuming that the ith detection period begins, the laser is turned on or the fiber is inserted to provide the optical signal; moreover, for a certain type of APD device, the optical signal is normal light. At this time, the APD outputs the first bias voltage in the first section of the i-th detection period, and the APD generates a photocurrent using the high voltage, and the photocurrent is fed back to the controller by the photocurrent detection circuit. After the controller receives the feedback, the first bias voltage is increased and output in the first interval, and the second bias voltage output in the second interval is kept unchanged. And then, if the optical signal keeps normal light all the time from the (i + 1) th detection period, the controller controls the bias circuit to continuously output the increased first bias voltage from the starting time point of the (i + 1) th detection period. Thus, from the i +1 th detection period, the bias voltage is close to the avalanche voltage, and there is no second section, and therefore, the APD operates normally. By adopting the scheme, the purpose that the APD identifies the scene without light to normal light is achieved.

Scene three': there is no light scene.

Referring to fig. 5C, after the bias voltage adjusting device is started, if the optical power of the optical signal is too low or no optical signal is applied to the APD, if the laser is not turned on and the optical fiber is not inserted, the bias circuit periodically outputs the bias voltage, and the APD cannot normally operate because the APD cannot be turned on in the second interval. In the first interval of the i-th detection period, the current value of the photocurrent is smaller than the second threshold, i.e. no light threshold, for example, 0 or a value close to 0, so that the APD considers that no light signal is input, the controller controls the bias circuit to output the first bias voltage in the first interval of the i + 1-th detection period, and output the second bias voltage in the second interval of the i + 1-th detection period. As such, the amplitude of the square wave in FIG. 5C remains unchanged.

In the above embodiment, in order to achieve large optical protection, i.e., to ensure that the APD machine is not damaged, the first threshold must be set. However, the second threshold is to identify a scene without light, a scene without light to normal light. If only a scene without light to high light is considered, the second threshold may not be set. Hereinafter, the embodiments of the present application will be described in detail with a view point of all three scenarios. For example, referring to fig. 6, fig. 6 is a flowchart of a bias voltage adjusting method provided in an embodiment of the present application, where the embodiment includes:

201. a protection function to protect the APD is initiated.

Illustratively, when the optical module is in operation, the protection function of the APD is activated.

202. The controller controls the bias circuit to output a first bias voltage in a first interval of an ith detection period and output a second bias voltage in a second interval of the ith detection period.

For a detailed description, refer to step 101 of fig. 2B, which is not described herein again.

203. The APD receives the optical signal and generates a photocurrent using the optical signal at a first bias voltage provided by the bias circuit during a first interval of an ith detection period.

For a detailed description, refer to step 102 in fig. 2B, which is not repeated here.

204. The photocurrent detection circuit detects the photocurrent to obtain a current value of the photocurrent.

205. The controller determines whether the current value exceeds a second threshold, and if the current value exceeds the second threshold, step 206 is executed; if the current value does not exceed the second threshold, step 204 is performed.

Wherein the second threshold is used for indicating the current value of the minimum photocurrent generated by the APD, the second threshold is a parameter which substantially distinguishes that no optical signal irradiates on the APD, and if the current value of the APD exceeds the second threshold, the APD is considered to have the optical signal irradiate on the APD; otherwise, the controller deems that no optical signal is impinging on the APD, and this second threshold may also be referred to as a no optical threshold.

For example, if the current value is greater than the non-light threshold, it is determined that a light signal is input to the APD, and if the current value is less than or equal to the non-light threshold, it is determined that a non-light signal is input to the APD. For example, the first bias voltage is 10V, the avalanche voltage is 30V, and when the bias voltage is 10V, if an optical signal with an optical power of 3dB is irradiated on the APD, which would result in the APD generating a minimum optical current, the second threshold may be set to a current value of the optical current generated by the APD, such as 1 milliamp (mA), when the optical signal with an optical power of 3dB is irradiated on the APD. When the current value of the photocurrent is less than 1mA, no light signal is considered to be input to the APD.

206. The controller judges whether the current value exceeds a first threshold, if so, the step 207 is executed; if the current value does not exceed the first threshold, step 208 is performed.

Wherein, the first threshold is used to indicate the minimum current value of the photocurrent generated when the APD is broken down, the first threshold is essentially a parameter for distinguishing whether the optical signal is normal light or large light, and the first threshold can also be called as a protection threshold.

For example, if the current value is greater than the protection threshold, the photocurrent generated by the APD is considered to damage the APD, and if the current value is less than or equal to the protection threshold, the photocurrent generated by the APD is considered to fail to damage the APD. For example, the first bias voltage is 10V, the avalanche voltage is 30V, and when the bias voltage is 10V, if an optical signal with an optical power of 5dB is irradiated on the APD, which may cause the APD to generate a photocurrent capable of damaging the APD, the first threshold may be set to a current value of the photocurrent generated by the APD, such as 2 milliamperes (mA), when the optical signal with the optical power of 3dB is irradiated on the APD.

207. The controller controls the bias circuit to reduce a first bias voltage in a first interval of the (i + 1) th detection period; step 204 is then performed.

Illustratively, the controller controls the bias circuit to output the reduced first bias voltage in the first interval of the (i + 1) th detection period, so that the APD cannot normally operate.

208. The controller controls the bias circuit to increase a first bias voltage in a first interval of the (i + 1) th detection period; step 209 is then performed.

Illustratively, the controller controls the bias circuit to output a boosted first bias voltage in a first interval of the (i + 1) th detection period, the boosted first bias voltage being close to the avalanche voltage.

209. The controller continuously outputs the increased first bias voltage from a start time point of the (i + 1) th detection period.

In the embodiment of fig. 6, the embodiment of the present application is described in detail from the perspective of considering all three scenarios. If no light scene or a scene of light reaching normal light is not considered, the current value and the second threshold do not need to be judged.

It should be noted that, in the process from off to on of the optical signal, the optical power of the optical signal first increases linearly, increases to the maximum value and then stabilizes, and the increase process is: none- > normal light- > steady large light, and correspondingly, the change process of the photocurrent is as follows: no- > second threshold- > first threshold- > is larger than the first threshold. The time for linear increase is short and is less than the time for the controller to process data. Therefore, in the above scenario from no light to large light, it is not necessary to worry that the controller may misjudge that the current is greater than the second threshold and smaller than the first threshold, and the first interval of the next detection period is controlled to output a high voltage, thereby damaging the APD. For example, see fig. 7.

Fig. 7 is a schematic diagram of linear increase of optical power in the method for protecting ADP provided by the embodiment of the application. It is assumed that a laser or an optical fiber can provide a large light. Before the ith detection period, the optical fiber is not inserted or the laser is not turned on, and the APD does not receive the optical signal. At this time, the waveform of the bias voltage is a periodic square wave. At the starting time point of the ith detection period, the optical fiber is not inserted or the laser is not turned on, the APD does not receive the optical signal, and the change process of the photocurrent corresponding to the optical signal is as follows: no- > second threshold- > first threshold- > is larger than the first threshold. As shown by the bold black curve, the black dots represent the second threshold and the gray dots represent the first threshold. Obviously, the linear growth time is short, and the current value is definitely larger than the first threshold, so that the situation that the bias circuit outputs high voltage in the first interval of the next detection period to damage the APD due to the fact that the controller treats the optical signal as normal light can be avoided.

It is understood that the above-mentioned bias voltage adjusting device can be independently arranged, and can also be arranged on the optical module. When the bias voltage adjusting device is independently disposed, it may be referred to as an APD receiver, or the like, and the embodiments of the present application are not limited thereto.

Fig. 8 is a schematic diagram of another bias voltage adjusting apparatus provided in the embodiment of the present application. Referring to fig. 8, the bias voltage adjusting apparatus 200 of the present embodiment includes:

a bias voltage output unit 21 for outputting a bias voltage;

an avalanche photodiode APD22 for generating a photocurrent with an optical signal under the action of the bias voltage;

a photocurrent detecting unit 23 for detecting the photocurrent to obtain a current value;

and the processing unit 24 is used for adjusting the bias voltage according to the current value.

In one possible design, the processing unit 24 is specifically configured to determine whether the current value exceeds a first threshold, where the first threshold is used to indicate a minimum current value of the photocurrent generated when the APD22 is broken down, and when the current value exceeds the first threshold, the bias voltage is reduced to disable the APD 22; when the current value does not exceed a first threshold, the bias voltage is raised such that the bias voltage approximates an avalanche voltage of the APD22, thereby enabling the APD22 to function properly.

In one possible design, the processing unit 24 is further configured to determine that the current value exceeds a second threshold before determining whether the current value exceeds a first threshold, the second threshold being used to indicate a minimum current value for distinguishing whether an optical signal is incident on the APD.

In a possible design, the processing unit 24 is further configured to control the bias voltage output by the bias voltage output unit 21 to remain unchanged when the current value does not exceed the second threshold.

In a possible design, the processing unit 24 is further configured to, before controlling the bias voltage output unit 21 to dynamically adjust the bias voltage according to the current value, control the bias voltage output unit 21 to output a periodically varying bias voltage according to detection periods, each of the detection periods includes a first interval and a second interval, a first bias voltage of the first interval is higher than a second bias voltage of the second interval, the first bias voltage is lower than an avalanche voltage of the APD22 and ensures that the APD22 operates, the second bias voltage disables the APD22, and the detection period is configured to indicate a period in which the photocurrent detection module detects the current value.

In a possible design, the processing unit 24 is specifically configured to control the bias voltage output unit 21 to dynamically adjust the first bias voltage according to the current value.

In one possible design, the processing unit 24 is specifically configured to decrease the first bias voltage when the current value of the photocurrent generated by the APD22 in the i-th detection period exceeds the first threshold, so that the APD22 cannot operate in the first interval of the i + 1-th detection period, where the i-th detection period and the i-th detection period are any two adjacent detection periods.

In one possible design, the first bias voltage output by the bias voltage output unit 21 in the first interval of the i-th detection period and the second bias voltage output by the second interval form any one of the following waveforms: square wave, sine wave, triangular wave, irregular wave.

In one possible design, the duration of the first interval is less than a first duration, the first duration indicating a maximum duration that the APD22 is not damaged when under the first bias voltage and subject to a maximum optical power; the duration of the second interval is greater than a second duration, which is used to indicate a response duration for the activation of APD 22.

Fig. 9 is a schematic diagram of another bias voltage adjusting apparatus provided in the embodiment of the present application. Referring to fig. 9, the bias voltage adjusting apparatus 300 of the present embodiment includes:

a processor 31 and a memory 32;

the memory 32 stores computer-executable instructions;

the processor 31 executes computer-executable instructions stored by the memory 32, causing the processor 31 to perform the bias voltage adjustment method described above.

For a specific implementation process of the processor 31, reference may be made to the above method embodiments, which implement the principle and the technical effect similarly, and details of this embodiment are not described herein again.

Optionally, the bias voltage adjusting apparatus 300 further comprises a communication interface 33. The processor 31, the memory 32, and the communication interface 33 may be connected by a bus 34.

In the above implementation of the bias voltage adjusting apparatus, the memory and the processor are directly or indirectly electrically connected to each other to realize data transmission or interaction, that is, the memory and the processor may be connected through an interface or may be integrated together. For example, the components may be electrically connected to each other via one or more communication buses or signal lines, such as a bus. The memory stores computer-executable instructions for implementing the data access control method, and includes at least one software functional module which can be stored in the memory in the form of software or firmware, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory.

The Memory may be, but is not limited to, a Random Access Memory (RAM), a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Read-Only Memory (EPROM), an electrically Erasable Read-Only Memory (EEPROM), and the like. The memory is used for storing programs, and the processor executes the programs after receiving the execution instructions. Further, the software programs and modules within the aforementioned memories may also include an operating system, which may include various software components and/or drivers for managing system tasks (e.g., memory management, storage device control, power management, etc.), and may communicate with various hardware or software components to provide an operating environment for other software components.

The processor may be an integrated circuit chip having signal processing capabilities. The Processor may be a general-purpose Processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

On the basis, the application also provides a chip, which comprises: logic circuit, input interface, wherein: the input interface is used for acquiring data to be processed; the logic circuit is used for executing the bias voltage adjusting method on the data to be processed to obtain the processed data.

Optionally, the chip may further include: and the output interface is used for outputting the processed data.

When the logic circuit executes the technical scheme of bias voltage adjustment, the data to be processed acquired by the input interface comprises the current value of photocurrent and the like, and the processed data output by the output interface comprises the adjustment amplitude of the bias voltage and the like.

The present application also provides a computer-readable storage medium for storing a program for performing the bias voltage adjustment method described in the foregoing embodiments when the program is executed by a processor.

Embodiments of the present application also provide a computer program product, which when running on a bias voltage adjusting apparatus, causes the bias voltage adjusting apparatus to execute the foregoing bias voltage adjusting method.

Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media capable of storing program codes, such as ROM, RAM, magnetic or optical disk, etc., and the specific type of media is not limited in this application.

Claims

A method of bias voltage adjustment, comprising:

acquiring the current value of photocurrent generated by an optical signal of an Avalanche Photodiode (APD) under the bias voltage provided by a bias circuit;

and controlling the bias circuit to dynamically adjust the bias voltage according to the current value.
The method of claim 1, wherein controlling the bias circuit to dynamically adjust the bias voltage according to the current value comprises:

judging whether the current value exceeds a first threshold, wherein the first threshold is used for indicating the minimum current value of the photocurrent generated when the APD is broken down;

when the current value exceeds the first threshold, reducing the bias voltage to render the APD inoperable; when the current value does not exceed a first threshold, raising the bias voltage such that the bias voltage approximates an avalanche voltage of the APD.
The method of claim 2, wherein before determining whether the current value exceeds the first threshold, further comprising:

and judging whether the current value exceeds a second threshold, wherein the second threshold is used for indicating whether the minimum current value of the APD is irradiated by the optical signal or not.
The method of claim 3, further comprising:

and when the current value does not exceed the second threshold, controlling the bias voltage output by the bias circuit to be kept unchanged.
The method of any of claims 1-4, before controlling the bias circuit to dynamically adjust the bias voltage according to the current value, further comprising:

the bias circuit is controlled to output bias voltage which changes periodically according to detection periods, each detection period comprises a first interval and a second interval, a first bias voltage of the first interval is higher than a second bias voltage of the second interval, the first bias voltage is smaller than an avalanche voltage of the APD and ensures that the APD works, the second bias voltage enables the APD not to work, and the detection period is used for indicating a period of detecting the current value by the photocurrent detection module.
The method of claim 5, wherein controlling the bias circuit to dynamically adjust the bias voltage according to the current value comprises:

and controlling the bias circuit to dynamically adjust the first bias voltage according to the current value.
The method of claim 6, wherein controlling the bias circuit to dynamically adjust the first bias voltage according to the current value comprises:

and when the current value of the photocurrent generated by the APD in the ith detection period exceeds the first threshold, reducing the first bias voltage so that the APD cannot work in the first interval of the (i + 1) th detection period, wherein the ith detection period and the ith detection period are any two adjacent detection periods.
A bias voltage adjustment device, comprising:

a bias circuit for providing a bias voltage;

an Avalanche Photodiode (APD) for generating a photocurrent by an optical signal under the action of the bias voltage;

a photocurrent detection circuit for detecting the photocurrent to obtain a current value;

and the controller is respectively coupled to the bias circuit and the photocurrent detection circuit and is used for controlling the bias circuit to adaptively adjust the bias voltage according to the current value.
The apparatus of claim 8,

the controller is specifically configured to determine whether the current value exceeds a first threshold, where the first threshold is used to indicate a minimum current value of a photocurrent generated when the APD is broken down, and when the current value exceeds the first threshold, reduce the bias voltage so that the APD cannot operate; when the current value does not exceed a first threshold, raising the bias voltage such that the bias voltage approximates an avalanche voltage of the APD, thereby causing the APD to operate normally.
The apparatus of claim 9,

the controller is further configured to determine that the current value exceeds a second threshold before determining whether the current value exceeds the first threshold, where the second threshold is used to indicate a minimum current value for distinguishing whether an optical signal is irradiated on the APD.
The apparatus of claim 10,

and the controller is also used for controlling the bias voltage output by the bias circuit to keep unchanged when the current value does not exceed the second threshold.
The apparatus as claimed in any one of claims 8-11, wherein the controller, before controlling the bias circuit to dynamically adjust the bias voltage according to the current value, is further configured to control the bias circuit to output a periodically varying bias voltage according to detection periods, each of the detection periods includes a first interval and a second interval, a first bias voltage of the first interval is higher than a second bias voltage of the second interval, the first bias voltage is lower than an avalanche voltage of the APD and ensures the APD to operate, the second bias voltage disables the APD, and the detection period is configured to instruct the photocurrent detection module to detect a period of the current value.
The apparatus of claim 12,

the controller is specifically configured to control the bias circuit to dynamically adjust the first bias voltage according to the current value.
The apparatus of claim 13,

the controller is specifically configured to reduce the first bias voltage when a current value of a photocurrent generated by the APD in an ith detection period exceeds the first threshold, so that the APD cannot operate in a first interval of the (i + 1) th detection period, where the ith detection period and the ith detection period are any two adjacent detection periods.
An optical module comprising the bias voltage adjusting apparatus according to any one of claims 8 to 14.
A light module, comprising: a processor, a memory for storing instructions, the processor for executing the instructions stored in the memory to implement the method of any one of claims 1 to 7.
A computer-readable storage medium for storing a computer program or instructions which, when run on a light module, causes the light module to perform the method of any of claims 1 to 7.
A computer program product, characterized in that, when run on a light module, causes the light module to perform the method according to any of claims 1 to 7.