A miniaturized asynchronous sampling dual optical frequency comb system

Abstract

The application relates to a miniaturized asynchronous sampling double optical frequency comb system, which comprises an integrated double optical comb laser and an integrated double optical comb driving control circuit, the integrated double optical comb laser comprises a first optical frequency comb laser and a second optical frequency comb laser, the resonant cavities of the first optical frequency comb laser and the second optical frequency comb laser are built in a full optical fiber form, the optical cavity length difference of the two resonant cavities is controlled in a micron level precision under the free running state of the two resonant cavities in the same environment condition through a special optical fiber length precision control method, and then the repetition frequency of the first optical frequency comb laser and the second optical frequency comb laser meets a preset small repetition frequency difference. Therefore, the application does not need to introduce an extra spatial optical path or a large-volume device such as an optical fiber delay line, maintains the full optical fiber structure of the double optical comb light source, realizes miniaturization, and guarantees the high consistency of the structures and parameters between the two optical combs.

Description

Technical Field

[0001] This invention relates to a miniaturized asynchronous sampling dual optical frequency comb system, and pertains to the field of optical frequency comb technology. Background Technology

[0002] Laser frequency combs are a newly emerging femtosecond laser technology that has become a powerful tool in many optical measurement fields due to their wide spectrum, low noise, and frequency stability. Measurement methods that use two optical frequency combs with a small repetition frequency difference as light sources for asynchronous sampling (such as dual-comb ranging) offer advantages such as high precision, high speed, and absolute standard traceability. With the increasing demands for accuracy and speed in industrial and aerospace applications, dual-comb measurement has surpassed or replaced traditional measurement methods in many fields. However, current dual-comb systems remain complex and bulky, making them unsuitable for use outside the laboratory and a major factor limiting the practical application of dual-comb measurement technology. Therefore, developing miniaturized and integrated dual-comb light sources is of great significance for the practical application of this emerging high-end technology.

[0003] Dual-comb light sources are not simply two individual optical frequency combs placed together for normal operation. They require a small and precise difference in the repetition frequencies of the two combs (for example, for a 50MHz repetition rate, the optimal difference is around 1kHz). While a single optical comb laser can be miniaturized using an all-fiber laser resonator structure and carefully coiled fiber, the tiny repetition frequency difference in a dual-comb system necessitates controlling the resonator length of the second laser with an accuracy on the order of 10 micrometers. This is impossible to achieve using conventional rulers to measure fiber length and cleavers. A common approach is to add an adjustable delay line within the resonator of the second laser, using a micrometer within the delay line to achieve high-precision repetition frequency adjustment. However, such devices require coupling the laser to spatial collimated light, as well as a precision translation stage and mirrors, resulting in a large volume. In some cases, the volume of a single delay line device can be larger than the volume of two all-fiber lasers. This undoubtedly contradicts the initial goal of miniaturization and introduces additional mechanical instabilities due to the spatial optical path. Therefore, miniaturization of dual-comb light sources and precise control of repetition rate remain an irreconcilable contradiction.

[0004] Furthermore, the high complexity of optical frequency comb systems largely stems from the numerous supporting drive and locking circuits, including multiple temperature control modules, pump drive modules, repetition rate detection and locking modules, and high-voltage drive modules. Even if the miniaturization of the optical components can be achieved, the large size and high power consumption of the circuitry will remain major challenges. Dual optical combs require twice the resources of single optical combs, and integrating and consolidating the various circuit sub-modules to achieve a size comparable to a miniaturized laser is a significant technical hurdle. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, in view of the above-mentioned problems, the object of the present invention is to provide a miniaturized, integrated, asynchronous sampling dual optical frequency comb system.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] In a first aspect, the present invention provides a miniaturized asynchronous sampling dual optical frequency comb system, characterized in that the system includes an integrated dual optical comb laser, the integrated dual optical comb laser including a first optical frequency comb laser and a second optical frequency comb laser, the resonant cavities of the first optical frequency comb laser and the second optical frequency comb laser are both constructed in an all-fiber configuration, and the difference in optical cavity length between the two resonant cavities under the same environmental conditions is controlled to a micrometer level through a special fiber length precision control method, thereby making the repetition frequency of the first optical frequency comb laser and the second optical frequency comb laser conform to a preset small repetition frequency difference.

[0008] Furthermore, the implementation of the special optical fiber length precision control method includes:

[0009] a) Reserve the corresponding pigtail length for each fiber device used to construct any (first or second) optical frequency comb laser resonator according to the design requirements, that is, reserve an extra small fiber length in a position that does not affect mode locking to facilitate subsequent removal.

[0010] b) Assemble the optical frequency comb laser and mode-lock it, measure the current repetition frequency, and calculate the length ΔL of intracavity fiber that needs to be removed:

[0011] c) If ΔL is too long and requires too much grinding time, in order to save manufacturing time, you can continue to roughly measure the length, remove some optical fibers and re-fuse the resonant cavity, and repeat step b) until ΔL is short enough to meet the set length requirements.

[0012] d) Grind the fiber end face using a fiber polishing device, and use a micrometer to control the length of fiber removed, so that the accuracy of fiber length variation can be controlled to the micrometer level.

[0013] e) After grinding away the appropriate fiber length (i.e., ΔL), polish the fiber end face with suitable sandpaper.

[0014] f) Clean and dry the polished optical fiber, re-fuse it to form a laser resonant cavity, and then lock it in mode. At this time, the repetition frequency of the laser is the preset repetition frequency value, which meets the requirement of the small repetition frequency difference of the dual optical comb system.

[0015] Furthermore, the formula for calculating ΔL is:

[0016]

[0017] Where c is the speed of light, n is the refractive index of the optical fiber at the laser wavelength, and f rep_goal For the target repetition frequency, f rep_cur This represents the current repetition frequency.

[0018] Furthermore, the system also includes a microcontroller control chip, an AD / DA chip, a power supply module, a first optical frequency comb control system, and a second optical frequency comb control system. The first and second optical frequency comb control systems have the same structure, both including a pump drive current source, a repetition frequency phase-locked loop, a temperature control module, and a high-voltage driver. The power supply module is used to connect to an external main power supply and convert it into a secondary power supply with appropriate parameters to power each electrical component. The AD / DA chip is used to perform digital-to-analog or analog-to-digital conversion on the signal. The reference clock is used to provide a reference frequency traceability standard for the two repetition frequency phase-locked loops. The pump drive current source, repetition frequency phase-locked loop, temperature control module, and high-voltage driver are respectively connected to the corresponding optical frequency comb lasers. The microcontroller control chip is used to connect to an external host computer to control the above-mentioned components.

[0019] Furthermore, the reference clock is a crystal oscillator or an external atomic clock.

[0020] Furthermore, the power supply module includes a switching power supply, a linear power supply, and a high-voltage power supply; both the switching power supply and the high-voltage power supply are used to connect to the external main power supply, the linear power supply is connected to the switching power supply, and the switching power supply achieves high-efficiency power voltage conversion through switching and energy storage devices to power the connected microcontroller main control chip, AD / DA chip, and temperature control module; the linear power supply is connected to the pump drive current source and the repetition frequency phase-locked loop respectively for power supply; the high-voltage power supply is connected to the high-voltage driver for power supply.

[0021] Secondly, the present invention also provides a method for fabricating a resonant cavity for an optical frequency comb laser based on fiber polishing, comprising:

[0022] S1. Reserve a section of fiber length for each fiber component of the optical frequency comb laser resonator in a position that does not affect mode locking, according to the design requirements.

[0023] S2. Assemble the optical frequency comb laser and mode-lock it. Measure the current repetition frequency and calculate the length ΔL of intracavity fiber that needs to be removed.

[0024] S3. If ΔL is too long, continue to roughly measure the length, remove some optical fibers and re-fuse the resonant cavity, and repeat step S2 until ΔL meets the polishing requirements.

[0025] S4. Grind the fiber end face using a fiber polishing device, and use a micrometer to control the length of fiber removed, controlling the fiber length to the micrometer level.

[0026] S5. After grinding off the appropriate length of optical fiber, polish the end face of the optical fiber with suitable sandpaper.

[0027] S6. Clean and dry the polished optical fibers on both sides, re-fuse them to form a laser resonant cavity, and then lock the mode. At this time, the repetition frequency of the laser is the preset repetition frequency value, which meets the requirement of the small repetition frequency difference of the dual optical comb system.

[0028] Furthermore, the formula for calculating ΔL is:

[0029]

[0030] Where c is the speed of light, n is the refractive index of the optical fiber at the laser wavelength, and f rep_goal For the target repetition frequency, f rep_cur This represents the current repetition frequency.

[0031] Furthermore, the fiber end face is ground using a fiber polishing device, and the length of the fiber removed is controlled by a micrometer. When the fiber length changes to the micrometer level, the length of the fiber removed is monitored by an optical frequency domain reflectometer during the polishing process.

[0032] Because the present invention adopts the above technical solution, it has the following characteristics:

[0033] 1. The dual-comb laser resonators of this invention are constructed entirely of optical fiber, which is easy to integrate and package. The cavity lengths of the two optical frequency comb laser resonators are precisely controlled by a special method of grinding the fiber end faces. The control accuracy of the length difference can reach the level of ten micrometers, so that the repetition frequency of the two lasers naturally has the desired small repetition frequency difference (e.g., 1 kHz). This allows for stretching and locking of the optical fiber with PZT to achieve precise customization of the repetition frequency difference. Therefore, this invention does not require the introduction of additional spatial optical paths or large optical fiber delay lines, maintaining the all-fiber structure of the dual-comb light source, achieving miniaturization, and ensuring a high degree of consistency in structure and parameters between the two optical combs.

[0034] 2. The dual optical comb system of the present invention does not simply put the circuits of two single optical combs together in the electronic drive control design, but integrates the shareable resources such as power supply, clock, and microcontroller control. This can make full use of system resources to prevent waste and redundancy, improve utilization efficiency, and further reduce circuit size and power consumption.

[0035] 3. Unlike the traditional separate control architecture of two optical frequency comb circuit systems, this invention integrates and unifies the circuit systems of the two optical frequency combs, saving resources such as power supply, chips, and clocks, while making the electrical noise of the two optical combs originate from the same source, improving the coherence between the output lasers of the two optical combs, and forming a complete miniaturized dual optical comb system with extremely high parameter similarity by combining with an integrated dual optical comb laser.

[0036] In summary, this invention enables the miniaturization of the entire dual optical comb system from both optical and electrical perspectives, and can be widely applied in the field of optical measurement. Attached Figure Description

[0037] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0038] Figure 1 This is a diagram of the architecture of a miniaturized asynchronous sampling dual optical frequency comb system according to an embodiment of the present invention. Detailed Implementation

[0039] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0040] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0041] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0042] Since dual-comb measurement is limited by the fact that the dual-comb system as a light source is still relatively complex and bulky, this invention provides a miniaturized asynchronous sampling dual optical frequency comb system, the main features of which are: (1) The resonant cavities of the dual-comb lasers are all built in the form of existing all-fiber, which is easy to integrate and package. The optical part of a single laser plus amplifier can be packaged to about the size of a palm. In view of the technical problem that it is difficult to accurately control the difference in repetition frequency between two all-fiber femtosecond lasers, this invention introduces fiber polishing technology to achieve the accuracy of the free-running repetition frequency difference to the order of hundreds of Hz without adding any additional components (such as fiber tunable delay lines). (2) The two optical frequency combs of this dual-comb system are not completely independent in the electrical control system, but share most of the resources, which prevents the waste and redundancy of resources, improves the utilization efficiency, and reduces the circuit size and power consumption. In summary, through the above-mentioned design of all-fiber laser resonator, chip-based circuit control system, and system resource sharing, the entire dual-comb system can be packaged in a mechanical structure with a volume of less than 2L, realizing the miniaturization of the dual-comb light source, and the difference between the two combs (except for the deliberately reserved repetition frequency difference) is very small.

[0043] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that the present invention does not limit the specific mode-locking method of the femtosecond laser resonator, nor does it limit the specific chip model used in the circuit system; selection can be made according to actual needs.

[0044] Example 1: As Figure 1 As shown, the miniaturized asynchronous sampling dual optical frequency comb system provided in this embodiment includes: a microcontroller control chip, an AD / DA chip, an external main power supply, a switching power supply, a linear power supply, a high-voltage power supply, a host computer, a reference clock, a first optical frequency comb control system, a second optical frequency comb control system, and an integrated dual optical frequency comb laser. The first and second optical frequency comb control systems have the same structure, both including a pump drive current source, a repetition frequency phase-locked loop, a temperature control module, and a high-voltage drive. The integrated dual optical frequency comb laser includes a first optical frequency comb laser and a second optical frequency comb laser.

[0045] Both the switching power supply and the high-voltage power supply are connected to the external main power supply. The linear power supply is connected to the switching power supply. The switching power supply can achieve high-efficiency power voltage conversion through switching and energy storage devices to power the microcontroller main control chip, AD / DA chip and temperature control module. The linear power supply is connected to the pump drive current source and the repetition frequency phase-locked loop for power supply. The high-voltage power supply is connected to the high-voltage driver for power supply.

[0046] AD / DA chips are used to perform digital-to-analog or analog-to-digital conversion on signals.

[0047] The reference clock is used to connect two repetition frequency phase-locked loops (PLLs). The reference clock is the clock reference and source of the reference frequency source in the PLL. It is usually a highly stable clock signal, which can be a crystal oscillator or a more stable atomic clock. The reference frequency source is a device that generates any other frequency value required by means of PLL or DDS based on the reference clock (for example, it can generate different frequencies such as 50.001MHz or 99.997MHz). It is the standard to which the repetition frequency signal in the PLL needs to be locked.

[0048] The pump drive current source, repetition frequency phase-locked loop, temperature control module and high voltage drive are connected to the corresponding optical frequency comb lasers via optical fiber or wire. Through special optical fiber length precision control, the difference in optical cavity length between the two optical frequency comb lasers in the free operation state is controlled within the range of ten micrometers (total length of several meters). This allows the repetition frequency of the two optical frequency comb lasers to naturally have the desired small repetition frequency difference (e.g., 1 kHz).

[0049] The host computer is used to control the microcontroller's main control chip to control the above-mentioned devices and to display the control process through a software interface.

[0050] In a preferred embodiment of the present invention, both optical comb laser resonators are constructed using an all-fiber architecture, which facilitates integration and packaging. A special fiber length precision control method ensures that the optical cavity length difference between the two optical comb resonators is controlled to within the tens of micrometers (total length several meters) under the same environmental conditions during free operation. This allows the repetition frequencies of the two lasers to naturally possess a desired small repetition rate difference (e.g., 1 kHz), eliminating the need for bulky components like fiber delay lines for additional adjustment, thus achieving miniaturization.

[0051] Furthermore, one implementation of the special optical fiber length precision control method can be as follows:

[0052] a) Reserve the corresponding pigtail length for each fiber device in the resonant cavity of any optical frequency comb laser in the dual-comb laser according to the design requirements. You can use a ruler to roughly measure to the millimeter level. However, reserve an extra length of about 1 cm at a certain position that does not affect the mode-locking effect. This is mainly because if the fiber is too long, it is easy to remove, but if the fiber is too short, it is difficult to continue the length.

[0053] b) Assemble the optical frequency comb laser and mode-lock it. Measure the current repetition frequency and calculate the required length of intracavity fiber to be removed using the following formula:

[0054]

[0055] Where c is the speed of light, n is the refractive index of the optical fiber at the laser wavelength, and f rep_goal For the target repetition frequency, f rep_cur This represents the current repetition frequency.

[0056] c) If the ΔL is too long and does not meet the set length requirement, continue to roughly measure the length with a ruler, remove some optical fibers and re-fuse the resonant cavity, and repeat step b) until the ΔL radiates to the set length requirement, for example, it can be about 2mm longer than the ideal cavity length.

[0057] d) Cut the fusion splice position with a fiber optic cleaver, place one end of the fiber into the fixture and fix it, and use a fiber polishing device to polish the fiber end face. Use a micrometer to control the length of the fiber removed. This can control the fiber length to the micrometer level. An optical frequency domain reflectometer (OFDR) can be used to monitor the length of the fiber removed during the polishing process.

[0058] e) After grinding off the appropriate fiber length, polish the fiber end face with fine-grit sandpaper. Otherwise, air bubbles may be generated during subsequent fiber splicing, introducing significant losses to the laser. If the unground fiber end face on the other side was not cut properly (e.g., the end face is uneven or the cut angle is too large), it also needs to be polished with fine sandpaper.

[0059] f) Clean and dry the ground optical fibers on both sides, re-fuse them to form a laser resonant cavity, and then lock the mode. At this time, the repetition frequency of the laser is the value expected at the beginning. If there is a slight deviation, the calculation formula can be corrected for systematic error.

[0060] In summary, the above methods can effectively adjust the repetition rate of an all-fiber femtosecond laser to the desired value, meet the requirement of a small repetition rate difference in a dual-comb system, achieve miniaturization of the dual-comb light source, and avoid the risk of large differences in other parameters between the two optical combs.

[0061] Furthermore, the two optical frequency combs in the dual-comb system are not completely independent in the electrical control system, but share most of the resources, preventing resource waste and redundancy, improving utilization efficiency, and reducing circuit size and power consumption. Specific implementation methods include:

[0062] a) Use the same power supply system.

[0063] Based on the varying power and ripple quality requirements of different functional modules within the dual optical combs, a unified power allocation method is employed. Modules with low ripple requirements, such as digital control circuits and temperature control circuits with high power demands, are powered by a DC-DC switching power supply to improve energy efficiency and reduce system heat generation. High-precision analog circuits requiring high ripple quality, such as the low-noise pump current drive module and the repetition frequency phase-locked loop module, are powered by a linear regulated power supply (e.g., LDO) to ensure good accuracy. The high-voltage drive modules of both optical combs are powered by the same high-voltage power supply to reduce complexity and crosstalk to other modules. This combined demand and overall power allocation method, compared to the traditional separate power supply for two optical combs, fully utilizes the output capacity of each power module and saves on the number of chips required. For example, high-voltage power supplies generally occupy a large area, have high cost, high static power consumption, and are more likely to cause strong interference to low-voltage circuits. However, one high-voltage power supply is sufficient to drive more than two loads. This invention integrates the two separate single-load high-voltage power supplies in two independent optical frequency combs into one dual-load high-voltage power supply, which can make full use of its output capacity to meet circuit requirements, and reduce the occupied area, heat consumption, cost and interference sources by half.

[0064] b) They are all controlled by the same master microcontroller chip and their working status is set and displayed by the same host computer software interface.

[0065] With the increasing prevalence of dual optical comb applications, the demand for dual optical comb light sources has essentially settled on two optical combs with nearly identical specifications and minimal repetition rate difference. Traditional discrete dual optical combs are not only complex to operate and switch, but also waste significant hardware resources of the microcontroller chip and the multi-channel resources of AD / DA chips. This invention uses a single microcontroller control chip and peripheral AD / DA chips to uniformly control and intelligently operate all modules of the two optical combs, improving hardware resource utilization, reducing circuit size and power consumption, and lowering the complexity for users.

[0066] c) All reference the same clock frequency source.

[0067] The repetition frequencies of a dual optical comb system need to be synchronized for proper operation. Each of the two independent optical combs has its own reference frequency source (a 10MHz internal crystal oscillator or an external atomic clock input), requiring clock synchronization to meet performance requirements. This invention combines the two optical combs into one, and the reference frequency source is also unified to the same frequency source. Therefore, it inherently possesses the same frequency and phase characteristics without the need for mutual synchronization.

[0068] Example 2: This example provides a method for fabricating a resonant cavity for an optical frequency comb laser based on fiber polishing, including:

[0069] S1. Reserve a section of fiber length for each fiber component of the optical frequency comb laser resonator in a position that does not affect mode locking, according to the design requirements.

[0070] S2. Assemble the optical frequency comb laser and mode-lock it. Measure the current repetition frequency and calculate the length ΔL of intracavity fiber that needs to be removed.

[0071] S3. If ΔL is too long, continue to roughly measure the length, remove some optical fibers and re-fuse the resonant cavity, and repeat step S2 until ΔL meets the polishing requirements.

[0072] S4. Grind the fiber end face using a fiber polishing device, and use a micrometer to control the length of fiber removed, controlling the fiber length to the micrometer level.

[0073] S5. After grinding off the appropriate length of optical fiber, polish the end face of the optical fiber with suitable sandpaper.

[0074] S6. Clean and dry the polished optical fibers on both sides, re-fuse them to form a laser resonant cavity, and then lock the mode. At this time, the repetition frequency of the laser is the preset repetition frequency value, which meets the requirement of the small repetition frequency difference of the dual optical comb system.

[0075] It should be noted that the method for preparing the optical frequency comb laser resonator based on fiber polishing in this embodiment is based on the same principle as the special fiber length precision control method in Embodiment 1. For details, please refer to Embodiment 1 and it will not be repeated here.

[0076] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In the description of this specification, the terms "a preferred embodiment," "furthermore," "specifically," "in this embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can refer to the different embodiments or examples described in this specification and different embodiments...

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A miniaturized asynchronous sampling dual optical frequency comb system, characterized in that, The system includes an integrated dual-comb laser, comprising a first optical frequency comb laser and a second optical frequency comb laser. The resonant cavities of both the first and second optical frequency comb lasers are constructed entirely of optical fiber. A special fiber length precision control method is used to control the optical cavity length difference between the two resonant cavities to a micrometer-level precision under the same environmental conditions during free operation. This ensures that the repetition frequencies of the first and second optical frequency comb lasers conform to a preset, small repetition frequency difference. The implementation of the special fiber length precision control method includes: a) Reserve a section of fiber length in a position that does not affect mode locking for each fiber device used to construct the resonant cavity of any optical frequency comb laser, according to the design requirements. b) Assemble the optical frequency comb laser and mode-lock it, measure the current repetition frequency, and calculate the length of intracavity fiber that needs to be removed. : ； in, c At the speed of light, n The refractive index of the optical fiber used at the operating laser wavelength. For the target repetition frequency, This represents the current repetition frequency. c) If After continuing the rough length measurement, remove some optical fibers and re-fuse the resonant cavity, repeating step b) until... Meets grinding requirements; d) Grind the fiber end face using a fiber polishing device, and use a micrometer to control the length of fiber removed, so that the accuracy of fiber length variation can be controlled to the micrometer level. e) Grind off the fiber length Then, polish the fiber end face using qualified sandpaper; f) Clean and dry the polished optical fiber, re-fuse it to form a laser resonant cavity, and then lock it in mode. At this time, the repetition frequency of the laser is the preset repetition frequency value, which meets the requirement of the small repetition frequency difference of the dual optical frequency comb system.

2. The miniaturized asynchronous sampling dual optical frequency comb system according to claim 1, characterized in that, The system also includes a microcontroller control chip, an AD / DA chip, a power supply module, a first optical frequency comb control system and a second optical frequency comb control system. The first optical frequency comb control system and the second optical frequency comb control system have the same structure, both including a pump drive current source, a repetition frequency phase-locked loop, a temperature control module and a high voltage drive. The power supply module is used to connect to the external main power supply and convert it into a secondary power supply to power various electrical devices; The AD / DA chip is used to perform digital-to-analog or analog-to-digital conversion on signals; A reference clock is used as a reference frequency traceability base for the two repetition frequency phase-locked loops described above. The pump drive current source, repetition frequency phase-locked loop, temperature control module and high voltage drive are respectively connected to the corresponding optical frequency comb laser; The microcontroller control chip is used to connect to an external host computer to control the above-mentioned devices.

3. The miniaturized asynchronous sampling dual optical frequency comb system according to claim 2, characterized in that, The reference clock is a crystal oscillator or an external atomic clock.

4. The miniaturized asynchronous sampling dual optical frequency comb system according to claim 2, characterized in that, The power supply module includes a switching power supply, a linear power supply, and a high-voltage power supply; Both the switching power supply and the high-voltage power supply are used to connect to the external main power supply. The linear power supply is connected to the switching power supply. The switching power supply achieves high-efficiency power voltage conversion through switching and energy storage devices to power the microcontroller main control chip, AD / DA chip and temperature control module. The linear power supply is connected to the pump drive current source and the repetitive frequency phase-locked loop for power supply. The high-voltage power supply is connected to the high-voltage driver for power supply.

5. A method for fabricating a resonant cavity for an optical frequency comb laser based on fiber polishing, characterized in that, include: S1. Reserve a section of fiber length for each fiber component of the optical frequency comb laser resonator in a position that does not affect mode locking, according to the design requirements. S2. Assemble the optical frequency comb laser and mode-lock it. Measure the current repetition frequency and calculate the length of intracavity fiber that needs to be removed. : ； in, c At the speed of light, n The refractive index of the optical fiber used at the operating laser wavelength. For the target repetition frequency, This represents the current repetition frequency. S3, if After continuing the rough length measurement, remove some optical fibers and re-fuse the resonant cavity. Repeat step S2 until... Meets grinding requirements; S4. Grind the fiber end face using a fiber polishing device, and use a micrometer to control the length of fiber removed, controlling the fiber length to the micrometer level. S5, Grind off the fiber optic length Then, polish the fiber end face using qualified sandpaper; S6. Clean and dry the polished optical fibers on both sides, re-fuse them to form a laser resonant cavity, and then lock the mode. At this time, the repetition frequency of the laser is the preset repetition frequency value, which meets the requirement of the small repetition frequency difference of the dual optical frequency comb system.

6. The method for fabricating a resonant cavity for an optical frequency comb laser according to claim 5, characterized in that, The fiber end face was ground using a fiber polishing device. The length of fiber removed was controlled by a micrometer. When the fiber length was controlled to change to the micrometer level, the length of fiber removed was monitored by an optical frequency domain reflectometer during the polishing process.

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