CN113572532B - Active phase compensation method and device for optical fiber interference ring and quantum key distribution system - Google Patents
Active phase compensation method and device for optical fiber interference ring and quantum key distribution system Download PDFInfo
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- CN113572532B CN113572532B CN202110402456.0A CN202110402456A CN113572532B CN 113572532 B CN113572532 B CN 113572532B CN 202110402456 A CN202110402456 A CN 202110402456A CN 113572532 B CN113572532 B CN 113572532B
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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
Technical Field
The application relates to the technical field of quantum communication, in particular to an optical fiber interference ring active phase compensation method and device and a quantum key distribution system.
Background
The method for carrying out secret communication by the quantum key distribution has absolute safety based on physical rules and is a very promising secret communication means. In the prior art, optical fibers are frequently used as channels for communication in the field of quantum key distribution, and the inventor finds that, in the conventional phase encoding method, the phase of the optical quantum carrying information is shifted and error codes are caused due to the influence of factors such as vibration of the environment where the communication optical fibers are located, temperature change and the like.
Disclosure of Invention
In view of the above, an object of the present application is to provide a method and an apparatus for active phase compensation of an optical fiber interference loop, and a quantum key distribution system, so as to reduce phase drift caused by environmental factors in a communication system.
In a first aspect, the present application provides an optical fiber interference ring active phase compensation method, which is applied to an optical fiber interference ring active phase compensation device, where the optical fiber interference ring active phase compensation device includes an interference ring and a plurality of temperature sensors, where the interference ring includes a first arm and a second arm formed based on an optical fiber optical path, and each temperature sensor is disposed 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 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.
In an optional embodiment, before 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, the method further includes:
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 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.
In an alternative embodiment, the step of calculating a phase difference value 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 comprises:
calculating real-time arm lengths of the first arm and the second arm according to a first formula according to the initial temperature and the real-time temperature of the first arm and the second arm;
and calculating the phase difference value according to the real-time arm lengths of the first arm and the second arm and a second formula.
In an alternative embodiment, the first formula is:
wherein α is a thermal expansion coefficient of the optical fiber, Ta1Is the real-time temperature, T, of the first arm a0Is the initial temperature of the first arm; t isb1Is the real-time temperature, T, of the second armb0Is the initial temperature of the second arm; l isa0Is the initial arm length of the first arm, Lb0Is the initial arm length of the second arm; l isa1Is the real-time arm length, L, of the first armb1Is the real-time arm length of the second arm.
In an alternative embodiment, 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; l isa0Is the initial arm length of the first arm, Lb0Is the initial arm length of the second arm; l isa1Is the real-time arm length, L, of the first armb1Is the real-time arm length of the second arm.
In an alternative 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 active phase compensation device for 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 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 configured 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 two compensated signal lights to obtain a phase-compensated signal light.
In an optional embodiment, the interference ring includes a beam splitter, a coupler and a phase modulator connected by an optical fiber, where the beam splitter is configured to split a signal light to be processed, and the coupler is configured to couple out two compensated signal lights; the phase modulator is used for performing phase compensation on the signal light in the interference ring;
wherein two optical fiber paths between the beam splitter and the coupler are respectively used as the first arm and the second arm; the phase modulator is located on the first arm or the second arm.
In an alternative embodiment, the interference ring further comprises a shock absorbing platform, and the interference ring is mounted on the shock absorbing platform.
In a third aspect, the present application provides a quantum key distribution system comprising the fiber optic interference ring active phase compensation device according to any one of the preceding embodiments.
The embodiment of the application has the following beneficial effects:
the optical fiber interference ring active phase compensation method, the optical fiber interference ring active phase compensation device and the quantum key distribution system adopt quantitative temperature measurement to indirectly obtain phase drift parameters caused by temperature, and transmit data to the phase modulator for compensation. Compared with the scheme that a part of communication code elements are consumed by an external electronic control system to actively capture and search the phase drift parameters in the prior art, the compensation of the temperature phase drift can be completed under the condition that more code elements are not consumed for monitoring; and the compensation is completed under the condition of not performing interruption or time division multiplexing, so that higher code forming rate is realized; required electronic equipment is all comparatively small-size, and the integration of being convenient for uses as the instrument.
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a flowchart illustrating an active phase compensation method for an optical fiber interference loop according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram illustrating an active phase compensation apparatus of an optical fiber interference ring according to an embodiment of the present application;
FIG. 3 is a schematic diagram illustrating the relationship between the position and the temperature of an optical fiber in an optical fiber interference ring according to an embodiment of the present application;
FIG. 4 is a flow chart illustrating another method for active phase compensation of an optical fiber interference loop according to an embodiment of the present application;
fig. 5 is a flowchart illustrating another method for active phase compensation of an optical fiber interference loop according to an embodiment of the present application.
Detailed Description
In order to make the objects, 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, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
At present, the current phase compensation methods mainly include three types |, which are as follows:
(1) the structure of the interference ring is improved to compensate the phase drift in an adaptive way, and the optical path is self-compensated by the compensation of the optical path structure or by using an optical instrument such as a Faraday mirror. The compensation scheme can effectively compensate the phase shift caused by the birefringence effect at present without an additional electronic control system, but the commonly used 'Plug-and-Play' system at present is vulnerable to Trojan horse attack.
(2) And passive compensation is adopted, and the fiber phase drift caused by temperature change or vibration-caused stress is reduced by good temperature insulation measures and shock absorption measures. However, this method can control the phase drift only at a low value, and it is impossible to completely control physical quantities such as temperature in principle.
(3) And active compensation, wherein parameters for searching phase drift are actively captured by an external electronic control system and are compensated by using a phase modulator. The method can compensate the phase drift value more accurately, but needs to consume a part of communication code elements for phase capture.
Therefore, the embodiment of the application provides an optical fiber interference ring active phase compensation method and device, which can bring corresponding phase compensation effects and the like with less cost. The following is described by way of example.
Example 1
Referring to fig. 1, the present embodiment provides an active phase compensation method for an optical fiber interference loop, which is applied to an active phase compensation device for an optical fiber interference loop.
The active phase compensation device of the fiber interference loop will be explained below.
As shown in FIG. 2, the active phase compensation device of the fiber interference loop comprises an interference loop, a plurality of temperature sensors and a processor. The interference ring comprises a beam splitter, a coupler and a phase modulator which are connected through optical fibers, and two optical fiber paths between the beam splitter and the coupler are respectively used as a first arm and a second arm; the phase modulator is located on the first arm or the second arm. The processor is electrically connected with the plurality of temperature sensors.
And the temperature sensors are arranged on the first arm and the second arm and are used for measuring to obtain the real-time temperatures of preset temperature measuring points on the first arm and the second arm. Exemplarily, the temperature sensors are distributed on the first arm and the second arm at certain intervals, and optionally, digital temperature sensors can be used at high density to achieve higher spatial resolution, so that high-precision measurement can be realized in an environment with a complex temperature field.
Optionally, the active phase compensation device for an optical fiber interference ring further includes a damping platform, and the interference ring and other devices may be mounted on the damping platform.
Generally, in the process of distributing the phase-coded quantum key, the influence of temperature change on an interference ring is far greater than that of mechanical vibration, the caused phase drift accounts for most of the interference ring and is a main factor causing bit errors in a communication system, and the phase drift caused by vibration can be well controlled by a simpler shock absorption measure. It can be understood that the optical fiber phase shift caused by temperature change or vibration-caused stress is reduced by good temperature insulation measures and shock absorption measures, and the active phase compensation method is combined on the basis of passive compensation, so that the phase compensation effect is better.
Based on the above-mentioned active phase compensation device for the optical fiber interference loop, the following describes the active phase compensation method for the optical fiber interference loop.
And the signal light to be processed respectively enters the first arm and the second arm after beam splitting. Exemplarily, the signal light to be processed is divided into two optical paths after passing through the beam splitter, and the two optical paths enter the first arm and the second arm of the interference ring respectively. The active phase compensation method for the optical fiber interference ring in this embodiment may be applied to a communication method using interference rings of different forms, and optionally, the interference ring may take a structure of a Mach-zehnder (MZ) interference ring or a Faraday-Michelson (FM) interference ring. For example, the method in this embodiment may be applied to a quantum key distribution system, where the signal light to be processed may be a signal light to be modulated (Alice end) or demodulated (Bob end) in the quantum key distribution system, and after entering the interference loop portion, the signal light to be processed is divided into two optical paths, and the two optical paths enter two arms of the interference loop respectively.
And step S110, 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.
Exemplarily, the temperatures of different positions in the interference ring can be obtained according to different positions of the preset temperature measuring point on the first arm and the second arm, that is, the corresponding relationship between the position of the optical fiber and the temperatures can be obtained based on the measurement of the temperature sensor. As shown in fig. 3, a solid line is an initial temperature, a dashed line is a real-time temperature, and a shaded area is a difference between the real-time temperature and the initial temperature, where the initial temperature may be a temperature of each preset temperature measurement point in an interference ring obtained in advance before the communication system starts communication, and the real-time temperature may be a temperature of each preset temperature measurement point measured at each time after the communication starts.
The preset temperature measuring points are densely distributed on the first arm and the second arm, that is, the preset temperature measuring points may be distributed at a certain interval, and generally, the smaller the interval of the preset temperature measuring points is, the more densely the temperature sensors are distributed, the more the obtainable correspondence between the positions of the optical fibers and the temperatures is close to the actual situation and the more accurate the correspondence is, so that, in the actual experiment operation, the interval of the preset temperature measuring points may be determined according to the temperature measuring accuracy required by the experiment, the size and the cost of the temperature sensors, and the like.
And step S120, 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.
For example, 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 of the first arm and the second arm measured by the temperature sensor and the real-time temperature data. For example, the temperature sensor may collect real-time temperature data at a certain time frequency and send the data to the processor, and the processor calculates the phase difference value of the two arms compared to the initial temperature based on the temperature data. The time frequency depends on the temperature change rate of the system, for example, in a communication system without passive compensation, the temperature stabilization time is about 20ms, and the acquisition frequency cannot be lower than 50 Hz.
Exemplarily, as shown in fig. 4, step S120 may include:
and step S121, calculating the real-time arm lengths of the first arm and the second arm according to a first formula and the initial temperature and the 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 damping measures, the phase change caused by vibration is far smaller than the influence of temperature factors, so how to compensate the phase drift caused by temperature change is mainly analyzed below. In general, since the change in the environmental temperature causes a change in the length of the optical fiber, that is, a change in the optical length affecting the interference ring, and further a phase shift occurs, the phase shift can be obtained from the change in the length of the optical fiber. It will be appreciated that given the thermal expansion coefficient of the fiber and the temperature change at each location of the fiber, the change in length of the fiber can be derived from a thermal expansion equation. Exemplarily, the real-time arm length of one arm of the interference ring can be calculated by the first formula, wherein the real-time arm length is the arm length after the temperature changes at a certain time. For example, the arm length change at a certain position may be obtained by multiplying the temperature difference at the certain position by the interval of the preset temperature measurement points and the thermal expansion coefficient, and the total arm length change may be obtained by integrating the arm length changes at the respective positions, in which case, the first formula may be expressed as:
Wherein α is the thermal expansion coefficient of the optical fiber, Ta1Is the real time temperature, T, of the first arma0Is the initial temperature of the first arm; t isb1Is the real-time temperature, T, of the second armb0Is the initial temperature of the second arm; l isa0Is the initial arm length of the first arm, Lb0Is the initial arm length of the second arm, La1Is the real-time arm length of the first arm, Lb1The real-time arm length of the second arm. Wherein the initial arm length is obtained by a preliminary measurement.
It can be understood that based on the corresponding relationship between the fiber position and the temperature, the real-time arm length can be calculated according to the obtained real-time temperature and the initial temperature according to the formula, so as to obtain the change of the arm length. As can be seen from the setting of the preset temperature measurement points, when the integral calculation is performed according to the first formula and the interval between the preset temperature measurement points is small enough and meets the requirement of the experimental precision, the real-time arm length can be calculated according to the obtained temperature change and the initial arm length of each position based on the corresponding relationship between the optical fiber position and the temperature as shown in fig. 3.
And step S122, calculating a phase difference value between the first arm and the second arm according to a 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 rings are not equal, the interference rings have a constant phase difference due to the inherent asymmetry, and if the arm lengths of the two arms of the interference rings are equal, the constant phase difference is zero. Taking the case of equal arm length as an example, since the change of the two arm lengths due to temperature may be different, the phase difference of the two interfered signal lights in the interference ring can be calculated by a second formula:
Wherein n is the refractive index of the fiber core of the optical fiber, λ is the wavelength of the signal light to be processed,
is the phase difference of the first arm and,
is the phase difference of the second arm and,
is the phase difference between the first and second arms.
For the phase difference of the first arm, 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 the temperature change can be calculated by the following fourth formula:
further, as can be seen from the fourth equation and the fifth equation, the phase difference between the two arms caused by the temperature change can also be calculated by the following equation:
in general, when the wavelength of the signal light, the material of the optical fiber, the arm length of the interference ring, the initial temperature calibrated when the communication is not started, and the real-time temperature, which is the temperature of each point of the interference ring at a certain time during the communication, are known, the phase deviation caused by the temperature drift of the two arms at any time can be obtained by the above formula. It can be understood that the above-mentioned other physical quantities are determined at the beginning of communication except for the real-time temperature at each point at a certain time, and the compensation for the fiber phase drift can be completed by inputting the calculated phase difference value into the phase modulator in the form of voltage.
Step S130, performing phase compensation 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 value of the two arms according to the above method, the processor may generate a corresponding voltage control signal according to the calculated phase difference value of the two arms, and transmit the voltage control signal to the phase modulator, and the phase modulator completes the compensation of the phase drift value caused by the temperature change in the communication system. The phase modulator in the above device may be located on the first arm or the second arm, and it can be understood that, according to the linear electro-optical effect, the effective refractive index of the phase modulator changes linearly with the voltage applied externally, that is, the refractive index of the light passing through the phase modulator can be changed by changing the driving voltage applied to the phase modulator, so as to implement the 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 correspondingly according to the requirements.
And step S140, coupling out the two compensated paths of signal light to obtain the signal light after phase compensation.
Exemplarily, the signal light to be processed is divided into two paths of optical signal light through the beam splitter, the two paths of optical signal light respectively enter the first arm and the second arm, then the two paths of signal light are output through the coupler in the device, and after the phase compensation device starts to work after communication, the phase compensated signal light can be output through the coupler.
In general, since the ambient temperature and the communication time may be different when the interference loop is manufactured, the phase difference of the optical fiber interference loop before the start of communication is not a predetermined standard phase difference, and therefore, the phase difference of the interference loop needs to be calibrated before communication.
In one embodiment, as shown in fig. 5, step S110 further includes:
and step S111, 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 step S112, measuring to obtain the initial temperatures of the first arm and the second arm at a preset temperature measuring point.
In an actual experimental environment, the phase difference can reach a preset phase difference standard value relatively difficultly and accurately by adjusting the arm length, exemplarily, coarse adjustment can be performed through the arm length, a section of temperature data and phase difference data are recorded by adjusting the arm length once, and the initial arm length can be obtained by fixing the arm length until the preset phase difference standard value appears. The temperature data corresponding to the initial arm length is used as an initial temperature for determining the ambient temperature change after communication.
The active phase compensation method of the optical fiber interference ring provided by the embodiment of the application is based on temperature measurement, and the corresponding phase needing to be compensated is calculated by the processor through the measured temperature, so that the corresponding compensation voltage is sent to the phase modulator to complete the phase compensation method, the phase drift parameter caused by the temperature is indirectly obtained, and the compensation of the temperature phase drift can be completed under the condition of monitoring without consuming more code elements; and compensation is completed under the condition of not performing interruption or time division multiplexing, and the higher code forming rate is realized. In addition, the electronic devices required by the method in the embodiment are small, and the integration of the electronic devices into an instrument is convenient.
Example 2
Referring to fig. 2, the present application provides an active phase compensation device for an optical fiber interference ring, which includes an interference ring, a plurality of temperature sensors, and a processor. 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.
And each temperature sensor is arranged on the first arm and the second arm, and measures to obtain the real-time temperature of a preset temperature measuring point on the first arm and the second arm.
The processor is electrically connected with the plurality of temperature sensors and is used 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 further used for carrying out phase compensation on the signal light in the first arm or the second arm according to the phase difference value, and coupling out the two paths of compensated signal light to obtain the signal light after the phase compensation.
In one embodiment, the interference ring comprises a beam splitter, a coupler and a phase modulator which are connected through an optical fiber, wherein the beam splitter is used for splitting the signal light to be processed, and the coupler is used for coupling out the compensated two paths of signal light; the phase modulator is used for performing phase compensation on the signal light in the interference loop. The two optical fiber optical paths between the beam splitter and the coupler are respectively used as a first arm and a second arm; the phase modulator is located on the first arm or the second arm.
Optionally, the phase compensation device further includes a damping platform, and the interference ring is mounted on the damping platform. It is to be understood that the apparatus of the present embodiment corresponds to the method of the above embodiment 1, and the alternatives of the above embodiment 1 are also applicable to the present embodiment, so that the description thereof will not be repeated here.
The application also provides a quantum key distribution system, which comprises the optical fiber interference ring active phase compensation device according to any one of the previous embodiments.
The device provided by the embodiment of the present application has the same implementation principle and technical effect as the foregoing method embodiments, and for the sake of brief description, reference may be made to the corresponding contents in the foregoing method embodiments where no part of the device embodiments is mentioned. It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the foregoing systems and apparatuses may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, a division of a unit is merely a division of one logic function, and there may be other divisions when actually implemented, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined or explained in subsequent figures, and moreover, the terms "first," "second," "third," etc. are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above examples are only specific embodiments of the present application, and are not intended to limit the technical solutions of the present application, and the scope of the present application is not limited thereto, although the present application is described in detail with reference to the foregoing examples, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope disclosed in the present application; such modifications, changes or substitutions do not depart from the spirit and scope of the present disclosure, which should be construed in light of the above teachings. Are intended to be covered by the scope of the present 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, Ta1Is the real-time temperature, T, of the first arma0Is the initial temperature of the first arm; t isb1Is the real-time temperature, T, of the second armb0Is the initial temperature of the second arm; l isa0Is the initial arm length of the first arm, Lb0Is the initial arm length of the second arm, La1Is the real-time arm length, L, of the first armb1Is 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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