CN113572532B - Active phase compensation method and device for optical fiber interference ring and quantum key distribution system - Google Patents

Abstract

The application provides an optical fiber interference ring active phase compensation method, an optical fiber interference ring active phase compensation device and a quantum key distribution system, wherein the method comprises the following steps: obtaining real-time temperatures of preset temperature measuring points on the first arm and the second arm based on the measurement of the temperature sensors; calculating a phase difference value between the first arm and the second arm according to the initial temperature and the real-time temperature of the first arm and the second arm; compensating the phase of the signal light in the first arm or the second arm according to the phase difference value; and coupling the compensated two paths of signal light to obtain the signal light after phase compensation. The method can complete the compensation of temperature phase drift under the condition of monitoring without consuming more code elements, and the required electronic equipment is small and convenient for integrated use.

Description

Optical fiber interference loop active phase compensation method, device and quantum key distribution system

technical field

The present application relates to the technical field of quantum communication, and in particular, to a method and device for active phase compensation of an optical fiber interference loop, and a quantum key distribution system.

Background technique

Confidential communication through quantum key distribution has absolute security based on physical rules, and is a very promising secure communication method. In the prior art, optical fibers are often used as channels for communication in the field of quantum key distribution. The inventor found in the research that the commonly used phase encoding method may cause vibration and temperature changes in the environment where the communication optical fiber is located. The phase of the light quantum that carries the information drifts, resulting in bit errors.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present application is to provide a method, device and quantum key distribution system for active phase compensation of optical fiber interference loops, so as to reduce the phase drift caused by the influence of environmental factors in the communication system.

In a first aspect, the present application provides an active phase compensation method for an optical fiber interference ring, which is applied to an active phase compensation device for an optical fiber interference ring. The active phase compensation device for an optical fiber interference ring includes an interference ring and a plurality of temperature sensors, wherein the interference The ring includes a first arm and a second arm formed based on an optical fiber path, and each temperature sensor is arranged on the first arm and the second arm; the signal light to be processed enters the first arm and the second arm respectively after being split into beams. in the second arm; the method includes:

Obtaining the real-time temperature of the preset temperature measurement points on the first arm and the second arm based on the measurement of the temperature sensor;

calculating a phase difference value between the first arm and the second arm according to the initial temperature of the first arm and the second arm and the real-time temperature;

performing phase compensation on the signal light in the first arm or the second arm according to the phase difference value;

The compensated two-way signal light is coupled and output to obtain the signal light after phase compensation.

In an optional embodiment, before the step of obtaining the real-time temperature of the preset temperature measurement points on the first arm and the second arm based on the temperature sensor measurement, the method further includes:

Adjusting the arm lengths of the first arm and the second arm so that the phase difference between the two arms reaches a preset phase difference standard value, and measuring the respective initial arm lengths of the first arm and the second arm;

The initial temperature of the first arm and the second arm at the preset temperature measurement point is obtained by measuring.

In an optional embodiment, the step of calculating the phase difference value between the first arm and the second arm according to the initial temperature of the first arm and the second arm and the real-time temperature ,include:

Calculate the real-time arm lengths of the first arm and the second arm according to the first formula according to the initial temperature and the real-time temperature of the first arm and the second arm;

The phase difference value is calculated according to the second formula according to the real-time arm lengths of the first arm and the second arm.

In an optional embodiment, the first formula is:

where α is the thermal expansion coefficient of the optical fiber, T _a1 is the real-time temperature of the first arm, T _a0 is the initial temperature of the first arm; T _b1 is the real-time temperature of the second arm, and T _b0 is The initial temperature of the second arm; L _a0 is the initial arm length of the first arm, L _b0 is the initial arm length of the second arm; L _a1 is the real-time arm length of the first arm, L _b1 is the real-time arm length of the second arm.

In an optional embodiment, the second formula is:

为所述第一臂的相位差，

为所述第二臂的相位差，

为所述第一臂和所述第二臂之间的相位差；L_a0为所述第一臂的初始臂长，L_b0为所述第二臂的初始臂长；L_a1为所述第一臂的实时臂长，L_b1为所述第二臂的实时臂长。where n is the refractive index of the fiber core, λ is the wavelength of the signal light to be processed,

is the phase difference of the first arm,

is the phase difference of the second arm,

is the phase difference between the first arm and the second arm; L _a0 is the initial arm length of the first arm, L _b0 is the initial arm length of the second arm; L _a1 is the first arm length The real-time arm length of one arm, L _b1 is the real-time arm length of the second arm.

In an optional embodiment, the interference ring is a Mach-Zehnder interference ring or a Faraday-Michelson interference ring.

In a second aspect, the present application provides an optical fiber interference ring active phase compensation device, comprising:

an interference ring, the interference ring includes a first arm and a second arm, and is used for splitting the signal light to be processed to obtain two signal lights, and the two signal lights enter the first arm and the second arm respectively in the arm;

a plurality of temperature sensors, each temperature sensor is arranged on the first arm and the second arm, and measures the real-time temperature of the preset temperature measurement points on the first arm and the second arm;

a processor, which is electrically connected to the plurality of temperature sensors and configured to calculate the first arm and the second arm according to the initial temperature of the first arm and the second arm and the real-time temperature The phase difference between the two arms;

The interference ring is also used to perform phase compensation on the signal light in the first arm or the second arm according to the phase difference value, and couple the compensated two-way signal light to obtain the phase-compensated signal light. signal light.

In an optional embodiment, the interference ring includes a beam splitter, a coupler and a phase modulator connected by an optical fiber, the beam splitter is used to split the signal light to be processed, and the coupler is used to split the compensated signal light. The two channels of signal light are coupled and output; the phase modulator is used to perform phase compensation on the signal light in the interference ring;

Wherein, the two optical fiber paths between the beam splitter and the coupler serve as the first arm and the second arm respectively; the phase modulator is located on the first arm or the second arm.

In an optional embodiment, a shock-absorbing platform is further included, and the interference ring is mounted on the shock-absorbing platform.

In a third aspect, the present application provides a quantum key distribution system, including the optical fiber interference ring active phase compensation device according to any one of the preceding embodiments.

The embodiments of the present application have the following beneficial effects:

The optical fiber interference loop active phase compensation method, device, and quantum key distribution system provided by the embodiments of the present application adopt quantitative temperature measurement to indirectly obtain temperature-induced phase drift parameters, and transmit the data to the phase modulator for compensation. Compared with the solution in the prior art in which the external electronic control system consumes part of the communication symbols to actively capture and search for the phase drift parameter, the compensation for the temperature phase drift can be completed without consuming more symbols for monitoring; Compensation is completed in the case of interruption or time division multiplexing, which has a higher coding rate; the required electronic equipment is relatively small, which is easy to integrate as an instrument for use.

In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the preferred embodiments are exemplified below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the following drawings will briefly introduce the drawings that need to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 shows a flowchart of a method for active phase compensation of an optical fiber interference ring provided by an embodiment of the present application;

FIG. 2 shows a schematic structural diagram of an optical fiber interference ring active phase compensation device provided by an embodiment of the present application;

FIG. 3 shows a schematic diagram of the relationship between the position of the optical fiber and the temperature in an optical fiber interference ring provided by an embodiment of the present application;

FIG. 4 shows a flowchart of another method for active phase compensation of an optical fiber interference ring provided by an embodiment of the present application;

FIG. 5 shows a flowchart of still another method for active phase compensation of an optical fiber interference ring provided by an embodiment of the present application.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

At present, there are mainly three types of phase compensation methods, as follows:

(1) The structure of the interference ring is improved to compensate the phase drift adaptively, and the optical path can complete self-compensation through the compensation of the optical path structure, or by using optical instruments such as Faraday mirrors. This compensation scheme can effectively compensate the phase shift caused by the birefringence effect without the need for an external electronic control system, but the currently commonly used "Plug-and-Play" system is vulnerable to Trojan horse attacks.

(2) Passive compensation, through good temperature insulation measures and shock absorption measures to reduce the phase drift of the fiber caused by temperature changes or stress caused by vibration. However, this method can only control the phase drift to a low value, and it is impossible to completely control physical quantities such as temperature in principle.

(3) Active compensation, the parameters of the search phase drift are actively captured and compensated by the phase modulator through the external electronic control system. This method can more accurately compensate the drift value of the phase, but it needs to consume a part of the communication symbols for phase capture.

To this end, the embodiments of the present application provide an active phase compensation method and device for an optical fiber interference ring, which can bring corresponding phase compensation effects and the like at a lower cost. The following description will be given by way of examples.

Example 1

Referring to FIG. 1 , this embodiment provides an active phase compensation method for an optical fiber interference ring, which is applied to an active phase compensation device for an optical fiber interference ring.

The optical fiber interference ring active phase compensation device will be described below.

As shown in FIG. 2 , the optical fiber interference ring active phase compensation device includes an interference ring, a plurality of temperature sensors, and a processor. The interference ring includes a beam splitter, a coupler and a phase modulator connected by an optical fiber, and the two optical fiber paths between the beam splitter and the coupler are used as the first arm and the second arm respectively; the phase modulator is located in the first arm. arm or second arm. The processor is electrically connected to a plurality of temperature sensors.

Each temperature sensor is arranged on the first arm and the second arm, and is used to measure and obtain the real-time temperature of the preset temperature measuring points on the first arm and the second arm. Exemplarily, the above temperature sensors are distributed at certain intervals on the first arm and the second arm. environment can still achieve high-precision measurement.

Optionally, the optical fiber interference ring active phase compensation device further includes a shock absorption platform, on which the above interference ring and other devices can be installed.

Generally, in the process of phase-encoded quantum key distribution, the influence of temperature change on the interference ring is far greater than that of mechanical vibration, and the phase drift caused by The induced phase shift can be well controlled by relatively simple damping measures. It can be understood that the phase drift of the optical fiber caused by temperature changes or stress caused by vibration can be reduced by good temperature insulation measures and shock absorption measures. On the basis of passive compensation, combined with the active phase compensation method, the phase compensation can be achieved. Better results.

Based on the above-mentioned active phase compensation device of the optical fiber interference ring, the active phase compensation method of the optical fiber interference ring will be described below.

The signal light to be processed enters the first arm and the second arm respectively after beam splitting. Exemplarily, the signal light to be processed is divided into two optical paths after passing through the above-mentioned beam splitter, and enters the first arm and the second arm of the interference ring respectively. The optical fiber interference loop active phase compensation method in this embodiment can be used in communication methods using different forms of interference loops. (FM, Faraday-Michelson) Structure of interference rings. For example, the method in this embodiment can be applied to a quantum key distribution system, and the above-mentioned signal light to be processed may be the signal light to be modulated (Alice end) or to be demodulated (Bob end) in the quantum key distribution system. After the interference ring part, the signal light to be processed is divided into two optical paths, respectively entering the two arms of the interference ring.

Step S110, obtaining the real-time temperature of the preset temperature measuring points on the first arm and the second arm based on the measurement of the temperature sensor.

Exemplarily, according to the different positions of the preset temperature measuring points on the first arm and the second arm, the temperature at different positions in the interference ring can be obtained, that is, the corresponding relationship between the position of the optical fiber and the temperature can be obtained based on the measurement of the temperature sensor. As shown in FIG. 3 , the solid line is the initial temperature, the dotted line is the real-time temperature, and the shaded area is the difference between the real-time temperature and the initial temperature, wherein the initial temperature may be each preset temperature in the interference ring obtained in advance before the communication system starts communication The temperature of the temperature measurement point, the real-time temperature may be the temperature of each preset temperature measurement point measured at each moment after the communication is started.

The above-mentioned preset temperature measurement points are densely distributed on the first arm and the second arm, that is, they can be distributed at certain intervals. Generally, the smaller the interval of the preset temperature measurement points, the more densely the temperature sensors are distributed, and the available optical fibers The closer the corresponding relationship between position and temperature is to the actual situation, the more accurate it is. Therefore, in the actual experimental operation, the interval of the above preset temperature measurement points can be determined according to the temperature measurement accuracy required by the experiment and the size and cost of the temperature sensor.

Step S120: Calculate the phase difference value between the first arm and the second arm according to the initial temperature and the real-time temperature of the first arm and the second arm.

Exemplarily, the processor in the above device may calculate the phase difference value between the first arm and the second arm according to the initial temperature and real-time temperature data of the first arm and the second arm measured by the temperature sensor. For example, the temperature sensor can collect real-time temperature data at a certain time frequency and send it to the processor, and the processor can calculate the phase difference between the two arms compared to the initial temperature based on the temperature data. Among them, the time frequency depends on the temperature change rate of the system. Taking a communication system without passive compensation as an example, the temperature stabilization time is about 20ms, and the acquisition frequency cannot be lower than 50Hz.

Exemplarily, as shown in FIG. 4 , step S120 may include:

Step S121: Calculate the real-time arm lengths of the first arm and the second arm according to the first formula according to the initial temperature and real-time temperature of the first arm and the second arm.

On the basis of the above device, after the influence of mechanical vibration is controlled by shock absorption measures, the phase change caused by vibration is far less than the influence of temperature factors. Therefore, the following mainly analyzes how to compensate the phase drift caused by temperature change. Generally, the change of the ambient temperature will cause the change of the fiber length, that is, the optical path of the interference ring will change, and then the phase shift will be generated. Therefore, the phase shift can be obtained by the change of the fiber length. It can be understood that if the thermal expansion coefficient of the optical fiber and the temperature change of each position of the optical fiber are known, the change of the optical fiber length can be obtained according to the thermal expansion formula. Exemplarily, the real-time arm length of one of the arms of the interference ring can be calculated by the first formula, where the real-time arm length is the arm length after the temperature changes at a certain moment. For example, the temperature difference at a certain position can be multiplied by the interval and thermal expansion coefficient of the preset temperature measurement points to obtain the arm length change at a certain position, and the total arm length change can be obtained by integrating the arm length changes at each position. The first formula can be expressed as:

where α is the thermal expansion coefficient of the fiber, T _a1 is the real-time temperature of the first arm, T _a0 is the initial temperature of the first arm; T _b1 is the real-time temperature of the second arm, T _b0 is the initial temperature of the second arm; L _a0 is the initial arm length of the first arm, L _b0 is the initial arm length of the second arm, L _a1 is the real-time arm length of the first arm, and L _b1 is the real-time arm length of the second arm. Among them, the initial arm length is obtained by pre-measurement.

It can be understood that, based on the correspondence between the position of the optical fiber and the temperature, the real-time arm length can be calculated according to the above formula according to the obtained real-time temperature and initial temperature, so as to obtain the change of the arm length. It can be seen from the settings of the above preset temperature measurement points that when the integral calculation is performed according to the above first formula, when the interval of the preset temperature measurement points is small enough and meets the requirements of the experimental accuracy, the position of the optical fiber as shown in Figure 3 can be used. The corresponding relationship between temperature and temperature, the real-time arm length is calculated according to the obtained temperature change at each position and the initial arm length.

Step S122: Calculate the phase difference value between the first arm and the second arm according to the second formula according to the real-time arm lengths of the first arm and the second arm.

Generally, if the arm lengths of the two arms of the interference ring are not equal, the interference ring has a constant phase difference due to the inherent asymmetry. If the two arms of the interference ring have the same length, the constant phase difference is zero. Here, the case where the arm lengths are equal will be taken as an example. Since the changes caused by the temperature to the lengths of the two arms may be different, for example, the phase difference between the two signal lights that interfere in the interference ring can be calculated from the second formula, The second formula is:

为第一臂的相位差，

为第二臂的相位差，

为第一臂和第二臂之间的相位差。where n is the refractive index of the fiber core, λ is the wavelength of the signal light to be processed,

is the phase difference of the first arm,

is the phase difference of the second arm,

is the phase difference between the first arm and the second arm.

As for the phase difference of the first arm, for example, the phase drift value of the first arm caused by the temperature change can be calculated by the following third formula:

Similarly, the phase shift value of the second arm caused by temperature changes can be calculated by the following fourth formula:

Further, from the fourth formula and the fifth formula, it can be concluded that the phase difference between the two arms caused by the temperature change can also be calculated by the following formula:

Generally, when the wavelength of the signal light, the fiber material, the arm length of the interference ring, the initial temperature calibrated when the communication is not started, and the temperature of each point of the interference ring during the communication, that is, the real-time temperature, can be obtained by the above formula. Phase deviation of the arms due to temperature drift. It can be understood that, except for the real-time temperature of each point at a certain moment, the other physical quantities mentioned above are all definite values at the beginning of communication. After the calculated phase difference value can be input into the phase modulator in the form of voltage, the matching can be completed. Compensation of fiber phase drift.

Step S130, phase compensation is performed on the signal light in the first arm or the second arm according to the phase difference value.

Exemplarily, after the processor completes the calculation of the phase difference between the two arms according to the above method, it can generate a corresponding voltage control signal according to the calculated phase difference between the two arms, and transmit the voltage control signal to the phase modulator, Compensation for phase drift values caused by temperature changes in the communication system is accomplished by the phase modulator. Wherein, the phase modulator in the above device can be located on the first arm or the second arm. It can be understood that, according to the linear electro-optic effect, the effective refractive index of the phase modulator changes linearly with the externally loaded voltage, that is, it can be applied to the The drive voltage on the phase modulator changes the refractive index of the light passing through the phase modulator to achieve phase modulation of the light. In addition, when the positions of the phase modulators are different, the control algorithm of the processor can be modified accordingly according to requirements.

In step S140, the two channels of signal light after compensation are coupled and outputted to obtain signal light after phase compensation.

Exemplarily, the signal light to be processed is divided into two paths of optical signal light after passing through the beam splitter, and enters the first arm and the second arm respectively, and then the two paths of signal light are output through the coupler in the above device, and the phase compensation is performed after the communication. After the device starts to work, the phase-compensated signal light can be output from the coupler.

Usually, the ambient temperature when the interference ring is made may be different from that during communication, so that the phase difference of the optical fiber interference ring before the communication starts is not the preset standard phase difference, so the phase difference of the interference ring needs to be calibrated before communication. .

In one embodiment, as shown in FIG. 5 , before step S110, it further includes:

Step S111 , adjusting the arm lengths of the first arm and the second arm so that the phase difference between the two arms reaches a preset phase difference standard value, and measuring the respective initial arm lengths of the first arm and the second arm.

Step S112, measuring the initial temperature of the first arm and the second arm at the preset temperature measurement point.

In the actual experimental environment, it is difficult to accurately make the phase difference reach the preset phase difference standard value by adjusting the arm length. Exemplarily, the arm length can be used for coarse adjustment, and each time the arm length is adjusted, a segment of temperature data and phase difference are recorded. Data until the preset phase difference standard value appears, at this time, the arm length can be fixed to obtain the initial arm length. The temperature data corresponding to the initial arm length is used as the initial temperature to obtain the environmental temperature change after communication.

The optical fiber interference ring active phase compensation method provided by the embodiment of the present application is based on the measurement of temperature. The processor calculates the corresponding phase that needs to be compensated based on the measured temperature, so as to send the corresponding compensation voltage to the phase modulator to complete the phase compensation method. The phase drift parameters caused by temperature are obtained indirectly, and the compensation for the temperature phase drift can be completed without consuming more symbols for monitoring; and the compensation can be completed without interruption or time division multiplexing. High bit rate. In addition, the electronic equipment required by the method in this embodiment is relatively small, which is convenient to be integrated into an instrument for use.

Example 2

Referring to FIG. 2 , the present application provides an optical fiber interference ring active phase compensation device, which includes an interference ring, a plurality of temperature sensors, and a processor. Wherein, the interference ring includes a first arm and a second arm for splitting the signal light to be processed to obtain two signal lights, and the two signal lights enter the first arm and the second arm respectively.

Each temperature sensor is arranged on the first arm and the second arm, and measures the real-time temperature of the preset temperature measuring points on the first arm and the second arm.

The processor is electrically connected with a plurality of temperature sensors for calculating the phase difference value between the first arm and the second arm according to the initial temperature and the real-time temperature of the first arm and the second arm.

The interference ring is also used to perform phase compensation on the signal light in the first arm or the second arm according to the phase difference value, and couple out the compensated two-way signal light to obtain the signal light after phase compensation.

In one embodiment, the interference ring includes a beam splitter, a coupler and a phase modulator connected by an optical fiber, the beam splitter is used for splitting the signal light to be processed, and the coupler is used for coupling out the compensated two-way signal light ; The phase modulator is used for phase compensation of the signal light in the interference ring. Wherein, the two optical fiber paths between the beam splitter and the coupler are used as the first arm and the second arm respectively; the phase modulator is located on the first arm or the second arm.

Optionally, the above-mentioned phase compensation device further includes a shock absorbing platform, and the interference ring is mounted on the shock absorbing platform. It can be understood that the apparatus of this embodiment corresponds to the method of the foregoing Embodiment 1, and the options in the foregoing Embodiment 1 are also applicable to this embodiment, so the description is not repeated here.

The present application also provides a quantum key distribution system, comprising the optical fiber interference ring active phase compensation device according to any one of the foregoing embodiments.

The implementation principles and technical effects of the devices provided in the embodiments of the present application are the same as those in the foregoing method embodiments. For brief description, for the parts not mentioned in the device embodiments, reference may be made to the corresponding content in the foregoing method embodiments. Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can be referred to the corresponding process in the above method embodiments, which will not be repeated here.

In the embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The apparatus embodiments described above are only illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated. to another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some communication interfaces, indirect coupling or communication connection of devices or units, which may be in electrical, mechanical or other forms.

Units described as separate components may or may not be physically separated, and components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in the embodiments provided in this application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

It should be noted that like numerals and letters refer to like items in the following figures, so that once an item is defined in one figure, it does not require further definition and explanation in subsequent figures, Furthermore, the terms "first", "second", "third", etc. are only used to differentiate the description and should not be construed as indicating or implying relative importance.

Finally, it should be noted that the above embodiments are only specific implementations of the present application, and are used to illustrate the technical solutions of the present application, but not to limit them. The protection scope of the present application is not limited thereto, although with reference to the foregoing embodiments The application has been described in detail, and those of ordinary skill in the art should understand that: any person skilled in the art can still modify or modify the technical solutions described in the foregoing embodiments within the technical scope disclosed in this application. Changes are easily thought of, or equivalent replacements are made to some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the present application. All should be covered within the scope of protection of this application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (7)

1. The active phase compensation method of the optical fiber interference ring is characterized by being applied to an active phase compensation device of the optical fiber interference ring, wherein the active phase compensation device of the optical fiber interference ring comprises an interference ring and a plurality of temperature sensors, the interference ring comprises a first arm and a second arm which are formed based on an optical fiber light path, and each temperature sensor is arranged on the first arm and the second arm; the signal light to be processed respectively enters the first arm and the second arm after beam splitting;

the method comprises the following steps:

obtaining real-time temperatures of preset temperature measuring points on the first arm and the second arm based on the measurement of the temperature sensor;

calculating a phase difference value between the first arm and the second arm according to the initial temperature and the real-time temperature of the first arm and the second arm;

performing phase compensation on signal light in the first arm or the second arm according to the phase difference value;

coupling the two compensated signal lights out to obtain a signal light after phase compensation;

the optical fiber interference ring active phase compensation device further comprises a processor, wherein the processor is electrically connected with the plurality of temperature sensors and is used for calculating a phase difference value between the first arm and the second arm according to the initial temperature and the real-time temperature of the first arm and the second arm;

The interference ring further comprises a beam splitter, a coupler and a phase modulator which are connected through optical fibers, wherein the beam splitter is used for splitting the signal light to be processed, the coupler is used for coupling the two compensated signal lights out, the phase modulator is used for performing phase compensation on the signal light in the interference ring, two optical fiber light paths between the beam splitter and the coupler are respectively used as the first arm and the second arm, and the phase modulator is located on the first arm or the second arm.

2. The method for active phase compensation of an optical fiber interference ring according to claim 1, wherein the step of obtaining real-time temperatures of preset temperature measuring points on the first arm and the second arm based on the temperature sensor measurement further comprises:

adjusting the arm lengths of the first arm and the second arm to enable the phase difference of the two arms to reach a preset phase difference standard value, and measuring to obtain the respective initial arm lengths of the first arm and the second arm;

and measuring to obtain the initial temperature of the first arm and the second arm at the preset temperature measuring point.

3. The method of claim 2, wherein the step of calculating the phase difference between the first arm and the second arm according to the initial temperature of the first arm and the second arm and the real-time temperature comprises:

Calculating real-time arm lengths of the first arm and the second arm according to a first formula and the real-time temperatures of the first arm and the second arm;

calculating the phase difference value according to the real-time arm lengths of the first arm and the second arm and a second formula;

the first formula is:

wherein α is the thermal expansion coefficient of the optical fiber, T_a1Is the real-time temperature, T, of the first arm_a0Is the initial temperature of the first arm; t is_b1Is the real-time temperature, T, of the second arm_b0Is the initial temperature of the second arm; l is_a0Is the initial arm length of the first arm, L_b0Is the initial arm length of the second arm, L_a1Is the real-time arm length, L, of the first arm_b1Is the real-time arm length of the second arm;

the second formula is:

wherein n is the refractive index of the fiber core of the optical fiber, and λ is the wavelength of the signal light to be processed,

is the phase difference of the first arm,

is the phase difference of the second arm,

is the phase difference between the first arm and the second arm.

4. The active phase compensation method for the optical fiber interference ring according to claim 1, wherein the interference ring is a Mach-Zehnder interference ring or a Faraday Michelson interference ring.

5. An active phase compensation device of an optical fiber interference ring, comprising:

the interference ring comprises a first arm and a second arm and is used for splitting the signal light to be processed to obtain two paths of signal light, and the two paths of signal light respectively enter the first arm and the second arm;

the temperature sensors are arranged on the first arm and the second arm and measure to obtain real-time temperatures of preset temperature measuring points on the first arm and the second arm;

a processor electrically connected to the plurality of temperature sensors for calculating a phase difference between the first arm and the second arm based on the initial temperature and the real-time temperature of the first arm and the second arm;

the interference ring is further used for performing phase compensation on the signal light in the first arm or the second arm according to the phase difference value, and coupling and outputting the two paths of compensated signal light to obtain signal light after phase compensation;

the interference ring comprises a beam splitter, a coupler and a phase modulator which are connected through optical fibers, wherein the beam splitter is used for splitting the signal light to be processed, the coupler is used for coupling the two compensated paths of signal light out, and the phase modulator is used for performing phase compensation on the signal light in the interference ring;

Two optical fiber paths between the beam splitter and the coupler are respectively used as the first arm and the second arm, and the phase modulator is positioned on the first arm or the second arm.

6. The active phase compensation device of claim 5, further comprising a damping platform, wherein the interference ring is mounted on the damping platform.

7. A quantum key distribution system, comprising the fiber optic interferometric ring active phase compensation device of any of claims 5-6.

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