阅读说明：本技术 激光器波长稳定控制方法及装置 (Laser wavelength stable control method and device ) 是由 唐世彪 代云启 周娟 于 2019-08-30 设计创作，主要内容包括：本发明提供一种激光器波长稳定控制方法及装置,所述激光器波长稳定控制装置包括：光束分束器,与激光器的输出端相连,对所述激光器的输出进行分光；波长监控回路,一端与所述光束分束器相连,另一端与所述激光器的输入端相连,根据从所述光束分束器获取的所述激光器的波长控制所述激光器的温度和外调制频率使得激光器输出稳定的目标波长。本发明具有高精度、电路结构简单、响应速度快的特点,可以为量子通信提供一种简单实用的波长稳定的激光光源。(The invention provides a method and a device for controlling the wavelength stability of a laser, wherein the device for controlling the wavelength stability of the laser comprises the following components: the beam splitter is connected with the output end of the laser and splits the output of the laser; and one end of the wavelength monitoring loop is connected with the beam splitter, the other end of the wavelength monitoring loop is connected with the input end of the laser, and the temperature and the external modulation frequency of the laser are controlled according to the wavelength of the laser obtained from the beam splitter so that the laser outputs a stable target wavelength. The invention has the characteristics of high precision, simple circuit structure and high response speed, and can provide a simple and practical laser light source with stable wavelength for quantum communication.)

1. A laser wavelength stabilization control apparatus, comprising:

the beam splitter is connected with the output end of the laser and splits the output of the laser;

and one end of the wavelength monitoring loop is connected with the beam splitter, the other end of the wavelength monitoring loop is connected with the input end of the laser, and the temperature and the external modulation frequency of the laser are controlled according to the wavelength of the laser obtained from the beam splitter so that the laser outputs a stable target wavelength.

2. The laser wavelength stabilization control device of claim 1, wherein the wavelength monitoring loop comprises:

the wavelength tracking module is connected with the beam splitter and used for acquiring the wavelength of the laser in real time;

the signal processing module is connected with the wavelength tracking module and determines an adjusting result for adjusting the temperature and the external modulation frequency of the laser according to a target wavelength and the real-time wavelength acquired by the wavelength tracking module;

and the wavelength control module is connected with the signal processing module and generates an adjusting signal according to an adjusting result output by the signal processing module to adjust the temperature and the external modulation frequency of the laser.

3. The laser wavelength stabilization control device according to claim 2, wherein the signal processing module includes:

and the rough adjusting unit is used for establishing a functional relation between the central wavelength of the laser and the temperature and the external modulation frequency, and determining a rough adjusting range for adjusting the temperature and the external modulation frequency of the laser according to the target wavelength and the functional relation.

4. The laser wavelength stabilization control device according to claim 3, wherein the coarse tuning unit includes:

the function determining unit is used for acquiring a wavelength-temperature curve and a wavelength-external modulation frequency curve by adopting a polynomial fitting method and determining the functional relation between the central wavelength and the temperature and the external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve;

and the second-order norm unit is used for acquiring wavelength points of the wavelength of the laser at the current temperature and the external modulation frequency on the curved surface formed by the functional relation, and determining a coarse adjustment range for adjusting the temperature and the external modulation frequency of the laser according to a second-order norm method, so that the wavelength points gradually move to be close to any point on a curve formed by the intersection of the target wavelength plane and the curved surface formed by the functional relation.

5. The laser wavelength stabilization control device according to claim 3 or 4, wherein the signal processing module further includes:

and the fine adjustment unit is connected with the coarse adjustment unit, controls the coarse adjustment unit to perform iterative calculation on the coarse adjustment result according to the coarse adjustment range and the target wavelength until the coarse adjustment result is smaller than a preset convergence value, and determines the coarse adjustment result as the fine adjustment range for adjusting the temperature and the external modulation frequency of the laser.

6. A method for controlling the wavelength stability of a laser, the method comprising:

splitting the output of the laser;

and controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by light splitting so that the laser outputs a stable target wavelength.

7. The method according to claim 6, wherein the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by the splitting comprises:

establishing a functional relation between the central wavelength of the laser and the temperature and the external modulation frequency;

and determining a coarse tuning range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relation.

8. The method of claim 7, wherein the establishing a functional relationship between the center wavelength of the laser and the temperature and the outer modulation frequency comprises:

respectively adopting a polynomial fitting method to obtain a wavelength-temperature curve and a wavelength-external modulation frequency curve;

determining the functional relation between the central wavelength and the temperature and the external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve;

the determining a coarse tuning range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relationship comprises:

acquiring wavelength points of the wavelength of the laser at the current temperature and the external modulation frequency on the curved surface formed by the functional relation;

and determining a coarse adjustment range for adjusting the temperature and the external modulation frequency of the laser according to a second-order norm method, so that the wavelength point gradually moves to be close to any point on a curve formed by the intersection of the target wavelength plane and a curved surface formed by the functional relation.

9. The method of claim 7, further comprising:

storing the functional relationship in the form of a lookup table.

10. The method according to claim 7 or 8, wherein the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by the splitting further comprises:

performing iterative calculation on the coarse tuning result according to the coarse tuning range and the target wavelength until the coarse tuning result is smaller than a preset convergence value;

determining the coarse tuning result as a fine tuning range for adjusting the temperature of the laser and the external modulation frequency.

Technical Field

The invention relates to the technical field of quantum communication, in particular to the technical field of lasers in quantum communication, and specifically relates to a method and a device for controlling the wavelength stability of a laser.

Background

The control precision of the laser is limited by the interval division granularity of linear approximation, and actually, the wavelength and each influence factor are not in a linear relation and can only be approximately considered to be linear in a small area division. To achieve higher accuracy, the regions must be divided small enough, which increases the computational load and does not fundamentally solve the problem.

The control accuracy is limited by the subdivision of the scanning steps, which are discrete quantities, whereas the variation of the stabilized wavelength is in principle a continuous quantity, the target value of the parameter most likely falling in the interval between two steps. To obtain higher accuracy, the steps can only be set small enough, which also increases the computational load.

In the prior art, a simple singlechip is generally adopted for control, and only simple calculation can be carried out, but high-speed and high-precision calculation cannot be carried out.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a method and an apparatus for controlling a laser wavelength stably, which are used to solve the problems of low control accuracy, complex control circuit and slow response speed in controlling a laser in the prior art.

To achieve the above and other related objects, the present invention provides a laser wavelength stabilization control apparatus, comprising: the beam splitter is connected with the output end of the laser and splits the output of the laser; and one end of the wavelength monitoring loop is connected with the beam splitter, the other end of the wavelength monitoring loop is connected with the input end of the laser, and the temperature and the external modulation frequency of the laser are controlled according to the wavelength of the laser obtained from the beam splitter so that the laser outputs a stable target wavelength.

In an embodiment of the present invention, the wavelength monitoring loop includes: the wavelength tracking module is connected with the beam splitter and used for acquiring the wavelength of the laser in real time; the signal processing module is connected with the wavelength tracking module and determines an adjusting result for adjusting the temperature and the external modulation frequency of the laser according to a target wavelength and the real-time wavelength acquired by the wavelength tracking module; and the wavelength control module is connected with the signal processing module and generates an adjusting signal according to an adjusting result output by the signal processing module to adjust the temperature and the external modulation frequency of the laser.

In an embodiment of the present invention, the signal processing module includes: and the rough adjusting unit is used for establishing a functional relation between the central wavelength of the laser and the temperature and the external modulation frequency, and determining a rough adjusting range for adjusting the temperature and the external modulation frequency of the laser according to the target wavelength and the functional relation.

In an embodiment of the present invention, the coarse tuning unit includes: the function determining unit is used for acquiring a wavelength-temperature curve and a wavelength-external modulation frequency curve by adopting a polynomial fitting method and determining the functional relation between the central wavelength and the temperature and the external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve; and the second-order norm unit is used for acquiring wavelength points of the wavelength of the laser at the current temperature and the external modulation frequency on the curved surface formed by the functional relation, and determining a coarse adjustment range for adjusting the temperature and the external modulation frequency of the laser according to a second-order norm method, so that the wavelength points gradually move to be close to any point on a curve formed by the intersection of the target wavelength plane and the curved surface formed by the functional relation.

In an embodiment of the present invention, the signal processing module further includes: and the fine adjustment unit is connected with the coarse adjustment unit, controls the coarse adjustment unit to perform iterative calculation on the coarse adjustment result according to the coarse adjustment range and the target wavelength until the coarse adjustment result is smaller than a preset convergence value, and determines the coarse adjustment result as the fine adjustment range for adjusting the temperature and the external modulation frequency of the laser.

The embodiment of the invention also provides a method for stably controlling the wavelength of the laser, which comprises the following steps: splitting the output of the laser; and controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by light splitting so that the laser outputs a stable target wavelength.

In an embodiment of the present invention, the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by splitting includes: establishing a functional relation between the central wavelength of the laser and the temperature and the external modulation frequency; and determining a coarse tuning range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relation.

In an embodiment of the present invention, the establishing a functional relationship between the central wavelength of the laser and the temperature and the external modulation frequency includes: respectively adopting a polynomial fitting method to obtain a wavelength-temperature curve and a wavelength-external modulation frequency curve; determining the functional relation between the central wavelength and the temperature and the external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve; the determining a coarse tuning range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relationship comprises: acquiring wavelength points of the wavelength of the laser at the current temperature and the external modulation frequency on the curved surface formed by the functional relation; and determining a coarse adjustment range for adjusting the temperature and the external modulation frequency of the laser according to a second-order norm method, so that the wavelength point gradually moves to be close to any point on a curve formed by the intersection of the target wavelength plane and a curved surface formed by the functional relation.

In an embodiment of the present invention, the method for controlling wavelength stability of a laser further includes: storing the functional relationship in the form of a lookup table.

In an embodiment of the present invention, the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by splitting further includes: performing iterative calculation on the coarse tuning result according to the coarse tuning range and the target wavelength until the coarse tuning result is smaller than a preset convergence value; determining the coarse tuning result as a fine tuning range for adjusting the temperature of the laser and the external modulation frequency.

As described above, the method and apparatus for controlling the wavelength stability of the laser according to the present invention have the following advantages:

the invention has the characteristics of high precision, simple circuit structure and high response speed, and can provide a simple and practical laser light source with stable wavelength for quantum communication.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a method for controlling wavelength stability of a laser according to the present invention.

Fig. 2 is a schematic flow chart illustrating the process of determining the coarse tuning range in the method for controlling the wavelength stability of the laser according to the present invention.

Fig. 3 is a schematic flow chart illustrating the functional relationship established in the method for controlling the wavelength stability of the laser according to the present invention.

FIG. 4 is a schematic diagram showing the functional relationship established in the method for controlling the wavelength stability of a laser according to the present invention.

Fig. 5 is a schematic flow chart illustrating a process of obtaining a coarse tuning range in the method for controlling the wavelength stability of a laser according to the present invention.

Fig. 6 is a schematic diagram showing a diagram of a coarse tuning range obtained by the method for controlling the wavelength stability of a laser according to the present invention.

Fig. 7 is a schematic flow chart illustrating the process of determining the fine tuning range in the method for controlling the wavelength stability of the laser according to the present invention.

FIG. 8 is a diagram illustrating a method for controlling the wavelength stability of a laser according to the present invention.

Fig. 9 is a schematic diagram of the wavelength stabilization control device of the laser according to the present invention.

Fig. 10 is a schematic block diagram of a signal processing module in the wavelength stabilization control device of the laser according to the present invention.

Fig. 11 is a schematic block diagram of a coarse tuning unit in the wavelength stabilizing control device of the laser according to the present invention.

Description of the element reference numerals

100 laser wavelength stable control device

110 light beam splitter

120 wavelength monitoring loop

121 wavelength tracking module

122 signal processing module

1221 coarse tuning Unit

1221a function determination Unit

1221b second order norm Unit

1222 fine tuning unit

123 wavelength control module

200 laser

S110 to S120

S121 to S124

S121 a-S121 b steps

S122 a-S122 b

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

Please refer to fig. 1 to 11. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the conditions under which the present invention can be implemented, so that the present invention has no technical significance, and any structural modification, ratio relationship change, or size adjustment should still fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention. In addition, the terms "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the terms is not to be construed as a scope of the present invention.

Example 1

The present embodiment aims to provide a method and an apparatus for controlling wavelength stability of a laser, which are used to solve the problems of low control accuracy, complex control circuit and slow response speed in controlling a laser in the prior art.

In the embodiment, the method and the device for controlling the wavelength stability of the laser establish a wavelength monitoring loop through a negative feedback system among the temperature of the laser, the external modulation frequency and the wavelength of the laser to stabilize the wavelength. The method comprises the steps of firstly carrying out coarse adjustment by adopting a second-order norm theory and a lookup table (LUT) control method, and then carrying out fine adjustment by adopting a least square iteration method (LSM), so that the defects of low wavelength control precision, complex control circuit and low reaction speed in the prior art are overcome.

The principle and the embodiment of the method and the device for controlling the wavelength stability of the laser according to the present invention will be described in detail below, so that those skilled in the art can understand the method and the device for controlling the wavelength stability of the laser without creative efforts.

Specifically, as shown in fig. 1, an embodiment of the present invention provides a method for controlling wavelength stability of a laser, where the method for controlling wavelength stability of a laser includes the following steps:

step S110, splitting the output of the laser;

and step S120, controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by light splitting so that the laser outputs a stable target wavelength.

The following describes steps S110 to S120 of the method for controlling the wavelength stability of the laser in this embodiment in detail.

Step S110 is to split the output of the laser.

The splitting ratio is 1-5: 95-99, the 1-5 split beams are used for control processing, the 95-99 split beams are used for normal output of the laser, for example, the splitting ratio is preferably 99:1, wherein 1% of the beams are used for control in the laser wavelength stabilization control method in the embodiment.

And step S120, controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by light splitting so that the laser outputs a stable target wavelength.

In this embodiment, the output wavelength of the laser is monitored in real time with a precision of ± 1pm, and then a wavelength control algorithm is executed, and the output control signal is used to control the temperature and the external modulation frequency of the laser.

Specifically, in this embodiment, as shown in fig. 2, the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by splitting includes:

step S121, establishing a functional relation among the central wavelength of the laser, the temperature and the external modulation frequency;

and S122, determining a coarse adjustment range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relation.

In this embodiment, as shown in fig. 3, the establishing a functional relationship between the central wavelength of the laser, the temperature, and the external modulation frequency includes:

step S121a, respectively obtaining a wavelength-temperature curve and a wavelength-external modulation frequency curve by a polynomial fitting method;

and step S121b, determining the functional relation between the central wavelength and the temperature and the external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve.

In the range of the working temperature of the laser, the temperature and the wavelength are in a linear relation, the temperature is increased, and the wavelength is shifted to the increasing direction. By measuring the relationship between temperature and wavelength and adopting a polynomial fitting method, the fitting coefficient is determined, and finally the wavelength-temperature curve is obtained.

Changing the external modulation frequency changes the number of times the laser emits light per unit time, which affects the operating temperature and also shifts the wavelength. And determining a fitting coefficient by measuring the relation of the wavelength and the external modulation frequency and adopting a polynomial fitting method to finally obtain a wavelength-external modulation frequency curve.

And determining a wavelength distribution function according to the two relations of the wavelength-temperature curve and the wavelength-external modulation frequency curve. Taking the temperature T and the external modulation frequency f as two independent variables, the wavelength λ can be expressed as a function of these two variables λ ═ H (T, f), as shown in fig. 4.

In this embodiment, the method for controlling the wavelength stability of the laser further includes: storing the functional relationship in the form of a lookup table. For example, the functional relationship may be written in the form of a look-up table in the FPGA chip.

In this embodiment, as shown in fig. 5, the determining a coarse tuning range for adjusting the temperature of the laser and the external modulation frequency according to the target wavelength and the functional relationship includes:

step S122a, acquiring wavelength points of the wavelength of the laser at the current temperature and the external modulation frequency on the curved surface formed by the functional relationship;

step S122b, determining a coarse tuning range for adjusting the temperature and the external modulation frequency of the laser according to a second-order norm method, so that the wavelength point gradually moves closer to any point on a curve formed by intersecting the target wavelength plane and a curved surface formed by the functional relationship.

For example, as shown in FIG. 6, the actual measured wavelength is λ_tAnd the target wavelength to be obtained is λ₀. The actually measured temperature T can be measured_tThe external modulation frequency f_tIndicated as point A (T) in the TOf plane_t,f_t)。

In fig. 4, λ is the plane where the target wavelength is located₀Intersecting the curved surface, the projection curve L of the intersection line on the TOf plane represents the wavelength lambda₀At a corresponding temperature T₀And an external modulation frequency f₀All possible combinations, as shown in fig. 6.

The distance from the point A to any point B on the L is expressed by a second-order norm as:

two parameters of temperature and external modulation frequency are changed, and the point A is moved to the point B, so that the target wavelength lambda can be obtained₀。

The parameter revision range can be determined according to the second-order norm, the logic is simple and clear, the calculation precision is high, and the operand is small. Typically, the frequency of the external modulation is a fixed constant (i.e., f)_t＝f₀) At the time of the above-mentioned operation,further simplified toThe calculation amount is greatly reduced. At this point, the first step of the coarse tuning process is completed.

In this embodiment, as shown in fig. 7, the controlling the temperature and the external modulation frequency of the laser according to the wavelength of the laser obtained by splitting further includes:

step S123, performing iterative calculation on the coarse tuning result according to the coarse tuning range and the target wavelength until the coarse tuning result is smaller than a preset convergence value;

step S124, determining the coarse tuning result as a fine tuning range for adjusting the temperature of the laser and the external modulation frequency.

In this embodiment, the parameter value to be adjusted is finally determined by the LSM algorithm.

Specifically, as shown in FIG. 8, the first step moves point A to within the neighborhood of the target point B, but fine tuning is still required to achieve greater control accuracy. Under the condition that f is not changed, the point A is gradually moved to the position of the point B by adopting an LSM iteration method.

Setting a preset convergence value epsilon small enough, when AB is less than or equal to epsilon, considering the calculation result to be converged, and finally obtaining accurate T_tAdjusting the value. Outputting the new feedback control value obtained by calculation toThe laser device is used for judging whether the output wavelength of the laser device reaches or keeps the corresponding target wavelength; if the target wavelength is not reached or kept, returning to execute the algorithm to enable the signal to reach or keep the target wavelength; if the target wavelength is reached or maintained, the wavelength stabilization control is continuously executed, so that the wavelength is accurately and stably controlled. Therefore, the laser wavelength stability control method of the embodiment improves the precision of wavelength real-time control, and realizes high-stability wavelength output of the laser in quantum communication.

Example 2

As shown in fig. 9, in order to implement the method for controlling the wavelength stability of the laser in embodiment 1, this embodiment provides a device 100 for controlling the wavelength stability of the laser, where the device 100 includes: a beam splitter 110 and a wavelength monitoring loop 120.

In this embodiment, the beam splitter 110 is connected to an output end of the laser 200, and splits the output of the laser 200.

The output of the laser 200 passes through the beam splitter 110, the splitting ratio of the beam splitter 110 is 1-5: 95-99, the 1-5 split beams enter the wavelength monitoring circuit 120 for control processing, and the 95-99 split beams are used for normal output of the laser 200, for example, the splitting ratio of the beam splitter 110 is 99:1, wherein 1% of the beams enter the wavelength monitoring circuit 120 for control of the wavelength monitoring circuit 120 in this embodiment.

In this embodiment, one end of the wavelength monitoring circuit 120 is connected to the beam splitter 110, and the other end is connected to the input end of the laser 200, and the temperature and the external modulation frequency of the laser 200 are controlled according to the wavelength of the laser 200 obtained from the beam splitter 110, so that the laser 200 outputs a stable target wavelength.

Specifically, in the present embodiment, as shown in fig. 9, the wavelength monitoring circuit 120 includes: a wavelength tracking module 121, a signal processing module 122 and a wavelength control module 123.

In this embodiment, the wavelength tracking module 121 is connected to the beam splitter 110, and is configured to obtain the wavelength of the laser 200 in real time. The wavelength tracking module 121 uses, for example, a wavelength meter to monitor the output wavelength of the laser 200 in real time with a precision of ± 1 pm. The output of the wavelength tracking module 121 is connected to the input of the signal processing module 122.

In this embodiment, the signal processing module 122 is connected to the wavelength tracking module 121, and determines an adjustment result for adjusting the temperature and the external modulation frequency of the laser 200 according to the target wavelength and the real-time wavelength obtained by the wavelength tracking module 121.

The main body of the signal processing module 122 is an FPGA, which executes a wavelength control algorithm, and the signal processing module 122 outputs an adjustment result to the wavelength control module 123.

In this embodiment, the wavelength control module 123 is connected to the signal processing module 122, and generates an adjustment signal according to the adjustment result output by the signal processing module 122 to adjust the temperature and the external modulation frequency of the laser 200.

Specifically, in the present embodiment, as shown in fig. 10, the signal processing module 122 includes: a rough adjusting unit 1221, configured to establish a functional relationship between the center wavelength of the laser 200 and the temperature and the external modulation frequency, and determine a rough adjusting range for adjusting the temperature and the external modulation frequency of the laser 200 according to the target wavelength and the functional relationship.

As shown in fig. 11, the coarse tuning unit 1221 includes: a function determination unit 1221a and a second-order norm unit 1221 b.

In this embodiment, the function determining unit 1221a obtains a wavelength-temperature curve and a wavelength-external modulation frequency curve by a polynomial fitting method, and determines a functional relationship between a central wavelength and a temperature as well as a functional relationship between a central wavelength and an external modulation frequency according to the wavelength-temperature curve and the wavelength-external modulation frequency curve.

Specifically, over the range of operating temperatures of laser 200, temperature is linear with wavelength, with increasing temperature and wavelength shifting in an increasing direction. By measuring the relationship between temperature and wavelength and adopting a polynomial fitting method, the fitting coefficient is determined, and finally the wavelength-temperature curve is obtained.

Changing the external modulation frequency changes the number of times the laser 200 emits light per unit time, thereby affecting the operating temperature and also causing wavelength drift. And determining a fitting coefficient by measuring the relation of the wavelength and the external modulation frequency and adopting a polynomial fitting method to finally obtain a wavelength-external modulation frequency curve.

And determining a wavelength distribution function according to the two relations of the wavelength-temperature curve and the wavelength-external modulation frequency curve. Taking the temperature T and the external modulation frequency f as two independent variables, the wavelength λ can be expressed as a function of these two variables λ ═ H (T, f), as shown in fig. 4.

In this embodiment, the second-order norm unit 1221b obtains a wavelength point formed by the wavelength of the laser 200 at the current temperature and the external modulation frequency on the curved surface formed by the functional relationship, and determines a coarse tuning range for adjusting the temperature and the external modulation frequency of the laser 200 according to a second-order norm method, so that the wavelength point gradually moves to be close to any point on a curve formed by intersecting the target wavelength plane and the curved surface formed by the functional relationship.

For example, as shown in FIG. 6, the actual measured wavelength is λ_tAnd the target wavelength to be obtained is λ₀. The actually measured temperature T can be measured_tThe external modulation frequency f_tIndicated as point A (T) in the TOf plane_t,f_t)。

In fig. 4, λ is the plane where the target wavelength is located₀Intersecting the curved surface, the projection curve L of the intersection line on the TOf plane represents the wavelength lambda₀At a corresponding temperature T₀And an external modulation frequency f₀All possible combinations, as shown in fig. 6.

The distance from the point A to any point B on the L is expressed by a second-order norm as:

by changing two parameters of temperature and external modulation frequency and moving the point A to the point BThe target wavelength lambda can be obtained₀。

The parameter revision range can be determined according to the second-order norm, the logic is simple and clear, the calculation precision is high, and the operand is small. Typically, the frequency of the external modulation is a fixed constant (i.e., f)_t＝f₀) At the time of the above-mentioned operation,further simplified toThe calculation amount is greatly reduced. At this point, the first step of the coarse tuning process is completed.

In this embodiment, as shown in fig. 10, the signal processing module 122 further includes: and a fine adjustment unit 1222, connected to the coarse adjustment unit 1221, for controlling the coarse adjustment unit 1221 to perform iterative calculation on the coarse adjustment result according to the coarse adjustment range and the target wavelength until the coarse adjustment result is smaller than a preset convergence value, and determining the coarse adjustment result as a fine adjustment range for adjusting the temperature and the external modulation frequency of the laser 200.

In this embodiment, the fine tuning unit 1222 finally determines the parameter value to be tuned through the LSM algorithm.

Specifically, as shown in FIG. 8, the first step moves point A to within the neighborhood of the target point B, but fine tuning is still required to achieve greater control accuracy. Under the condition that f is not changed, the point A is gradually moved to the position of the point B by adopting an LSM iteration method.

Setting a preset convergence value epsilon small enough, when AB is less than or equal to epsilon, considering the calculation result to be converged, and finally obtaining accurate T_tAdjusting the value. Outputting the calculated new feedback control value to the laser 200, and judging whether the output wavelength of the laser 200 reaches or is kept at the corresponding target wavelength; if the target wavelength is not reached or kept, returning to execute the algorithm to enable the signal to reach or keep the target wavelength; if the target wavelength is reached or maintained, the wavelength stabilization control is continuously executed, so that the wavelength is accurately and stably controlled. Therefore, the laser wavelength stability control of the present embodimentThe apparatus 100 improves the precision of the wavelength real-time control, and realizes the highly stable wavelength output of the laser 200 in the quantum communication.

In conclusion, the invention has the characteristics of high precision, simple circuit structure and high response speed, and can provide a simple and practical laser light source with stable wavelength for quantum communication. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention shall be covered by the claims of the present invention.