All-fiber double-optical-comb laser source with continuously adjustable frequency difference

Abstract

The utility model discloses an all-fiber double-optical-comb laser source with continuously adjustable frequency difference, which relates to the technical field of laser sources and comprises a pump laser, a first wavelength division multiplexer, an erbium-doped fiber, a polarization controller, a mode locking device, an output coupler and a second wavelength division multiplexer which are sequentially connected. The device also comprises a first isolator, a third wavelength division multiplexer, a second isolator and an optical fiber delay line. According to the all-fiber double-optical-comb laser source, the structure of the all-fiber double-optical-comb laser source is designed, the optical signal of the output coupler is divided into two mode-locked pulses through the second wavelength division multiplexer, continuous tuning of the repetition frequency difference of the two mode-locked pulses is achieved through adjustment of the optical fiber delay line, and the tuning range is large.

Description

Technical Field

[0001] The present application relates to the technical field of laser sources, and in particular to an all-fiber dual-comb laser source with continuously adjustable frequency difference. Background Art

[0002] Generating a stable, reliable and highly coherent dual-comb light source is a crucial step in dual-comb spectroscopy measurement. In the current scheme for generating dual-comb light sources, two mode-locked laser pulses with different frequencies are generally generated in the same mode-locked laser. The two pulses experience the same environment in the resonant cavity. Effective common-mode noise suppression can ensure that the laser achieves high coherence between the optical frequency combs under free operation, greatly simplifying the complexity of the system. Similar to the apodization operation of Fourier spectroscopy measurement technology, dual-comb measurement also requires selecting a time window T less than a complete cycle to intercept the interference signal. At this time, the apodization resolution f fres =f r / (Δf r T), where f r is the laser pulse repetition frequency related to the laser cavity length, Δf r is the difference in repetition frequency of the two laser pulses. r It is also the repetition frequency of the down-conversion RF comb. The dual-comb RF interference signal is expressed as Δf r is a series of interference patterns with equal time intervals at the repetition frequency. Each interference pattern contains complete spectral information. Therefore, the repetition frequency difference Δf of the dual-comb light source is r Directly determines the sampling speed of the system and the single measurement time 1 / Δf r Therefore, how to change the frequency difference of the dual optical combs is a problem that needs to be solved.

[0003] In the prior art, Chinese patent CN114268007A discloses a bidirectional mode-locked fiber laser for generating a dual optical comb, comprising: a first pump source, a second pump source, and a fiber ring resonator formed by sequentially connecting a first wavelength division multiplexer, an erbium-doped fiber, a second wavelength division multiplexer, a repetition rate adjustment module, a third polarization controller, and a first optical coupler; the first pump source and the second pump source are respectively connected to the first wavelength division multiplexer and the second wavelength division multiplexer; the repetition rate adjustment module comprises a first optical circulator and a second optical circulator; an optical delay line, a first polarization controller, and a first polarization-dependent isolator are sequentially connected between a first port of the first optical circulator and a third port of the second optical circulator; a second polarization-dependent isolator and a second polarization controller are sequentially connected between a first port of the second optical circulator and a third port of the first optical circulator.

[0004] At present, changing the repetition frequency difference of the dual optical comb is solved by changing the gain and polarization of the laser pulse in the cavity. The above solution can only be adjusted within a small range (the tuning range is several hundred Hz). However, the above-mentioned prior art does not solve this problem, and the tuning range of the difference in the repetition frequency of the two mode-locked pulses is small. Utility Model Content

[0005] The present application provides an all-fiber dual-comb laser source with a continuously adjustable frequency difference, which is used to solve the problem of a small tuning range of the difference in repetition frequency of two mode-locked pulses in the existing laser source technology.

[0006] On the one hand, the present application provides an all-fiber dual-comb laser source with continuously adjustable frequency difference, including: a pump laser, a first wavelength division multiplexer, an erbium-doped optical fiber, a polarization controller, a mode-locked device, an output coupler, and a second wavelength division multiplexer connected in sequence; and also includes: a first isolator, a third wavelength division multiplexer, a second isolator, and an optical fiber delay line.

[0007] The output coupler is connected to the b-port of the second wavelength division multiplexer.

[0008] The c-port of the second wavelength division multiplexer is connected to the d-port of the third wavelength division multiplexer through the first isolator.

[0009] The a port of the second wavelength division multiplexer is connected to the f port of the third wavelength division multiplexer through the second isolator and the optical fiber delay line in sequence.

[0010] The e-port of the third wavelength division multiplexer is connected to the first wavelength division multiplexer.

[0011] In a possible implementation, the pump laser is a 980 nm semiconductor laser.

[0012] In a possible implementation manner, a frequency division range of the first wavelength division multiplexer is 980 / 1550 nm.

[0013] In a possible implementation, the mode-locking device includes a semiconductor saturable absorber mirror, a carbon nanotube, and graphene.

[0014] In a possible implementation manner, the frequency division range of the second wavelength division multiplexer and the third wavelength division multiplexer are both 1530 / 1560 nm.

[0015] Among them, the a port, b port and c port of the second wavelength division multiplexer are 1560nm, 1530nm and 1530nm respectively, and the d port, e port and f port of the third wavelength division multiplexer are 1530nm, 1560nm and 1560nm respectively.

[0016] In a possible implementation, the central wavelengths of the first isolator and the second isolator are both 1550 nm.

[0017] In a possible implementation, the optical fiber delay line operates at a central wavelength of 1550 nm.

[0018] In a possible implementation, an all-fiber dual-comb laser source with continuously adjustable frequency difference adopts an all-fiber structure.

[0019] The all-fiber dual-comb laser source with continuously adjustable frequency difference in this application has the following advantages:

[0020] By designing the structure of the all-fiber dual-comb laser source, the optical signal of the output coupler is divided into two mode-locked pulses through the second wavelength division multiplexer. The difference in the repetition frequency of the two mode-locked pulses can be continuously tuned by adjusting the fiber delay line. This has a large tuning range and can achieve continuous tunability from 1 Hz to MHz level.

[0021] The proposed all-fiber dual-comb laser source adopts an all-fiber structure and does not require spatial light adjustment, which can significantly reduce the size of the equipment and increase the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of an all-fiber dual-comb laser source with continuously adjustable frequency difference provided in an embodiment of the present application.

[0024] Description of reference numerals:

[0025] 1- pump laser, 2- first wavelength division multiplexer, 3- erbium-doped optical fiber, 4- polarization controller, 5- mode locking device, 6- output coupler, 7- second wavelength division multiplexer, 8- first isolator, 9- third wavelength division multiplexer, 10- second isolator, 11- optical fiber delay line. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] like Figure 1 As shown, an embodiment of the present application provides an all-fiber dual-comb laser source with continuously adjustable frequency difference, including: a pump laser 1, a first wavelength division multiplexer 2, an erbium-doped fiber 3, a polarization controller 4, a mode-locked device 5, an output coupler 6, and a second wavelength division multiplexer 7 connected in sequence; and also includes: a first isolator 8, a third wavelength division multiplexer 9, a second isolator 10, and an optical fiber delay line 11.

[0028] The output coupler 6 is connected to the port b of the second wavelength division multiplexer 7 .

[0029] The c-port of the second wavelength division multiplexer 7 is connected to the d-port of the third wavelength division multiplexer 9 through the first isolator 8 .

[0030] The a port of the second wavelength division multiplexer 7 is connected to the f port of the third wavelength division multiplexer 9 through the second isolator 10 and the optical fiber delay line 11 in sequence.

[0031] The e-port of the third wavelength division multiplexer 9 is connected to the first wavelength division multiplexer 2 .

[0032] Specifically, in this embodiment, the pump laser 1 inputs the pump light into the erbium-doped optical fiber 3 through the first wavelength division multiplexer 2, and then passes through the polarization controller 4, the mode-locking device 5, and the output coupler 6 to reach the second wavelength division multiplexer 7; the second wavelength division multiplexer 7 divides the signal light received at the b port into two mode-locked pulses, one of which is output from the c port of the second wavelength division multiplexer 7, and then passes through the first isolator 8 to reach the d port of the third wavelength division multiplexer 9, and is output from the e port of the third wavelength division multiplexer 9; the other mode-locked pulse is output from the a port of the second wavelength division multiplexer 7, and then passes through the second isolator 10 and the optical fiber delay line 11 to reach the f port of the third wavelength division multiplexer 9, and is output from the e port of the third wavelength division multiplexer 9. The difference between the repetition frequencies of the two mode-locked pulses can be continuously tuned by adjusting the optical fiber delay line 11.

[0033] Exemplarily, the pump laser 1 is a 980nm semiconductor laser.

[0034] Exemplarily, the frequency division range of the first wavelength division multiplexer 2 is 980 / 1550 nm.

[0035] Exemplarily, the mode-locking device 5 includes a semiconductor saturable absorber mirror, a carbon nanotube, and graphene.

[0036] Exemplarily, the frequency division ranges of the second wavelength division multiplexer 7 and the third wavelength division multiplexer 9 are both 1530 / 1560 nm.

[0037] Among them, the a port, b port and c port of the second wavelength division multiplexer 7 are 1560nm, 1530nm and 1530nm respectively, and the d port, e port and f port of the third wavelength division multiplexer 9 are 1530nm, 1560nm and 1560nm respectively.

[0038] Exemplarily, the central wavelengths of the first isolator 8 and the second isolator 10 are both 1550 nm.

[0039] Exemplarily, the optical fiber delay line 11 operates at a central wavelength of 1550 nm.

[0040] Exemplarily, an all-fiber dual-comb laser source with continuously adjustable frequency difference adopts an all-fiber structure.

[0041] Specifically, in a possible embodiment, a dual-comb measurement is performed using an all-fiber dual-comb laser source with a continuously adjustable frequency difference of the present application, and a dual-comb laser pulse with an adjustable repetition frequency is output through an output coupler 6 of an all-fiber dual-comb laser source with a continuously adjustable frequency difference of the present application. The dual-comb laser pulse passes through a gas absorption cell and reaches a detector, and then a data acquisition and processing system performs Fourier transform processing on the signal detected by the detector, thereby obtaining an absorption spectrum signal of the measured gas.

[0042] The embodiment of the present application designs the structure of an all-fiber dual-comb laser source, divides the optical signal of the output coupler 6 into two mode-locked pulses through the second wavelength division multiplexer 7, and realizes continuous tunability of the difference in repetition frequency of the two mode-locked pulses by adjusting the optical fiber delay line 11. It has a large tuning range and can achieve continuous tunability from 1 Hz to MHz level.

[0043] The proposed all-fiber dual-comb laser source adopts an all-fiber structure and does not require spatial light adjustment, which can significantly reduce the size of the equipment and increase the stability of the system.

[0044] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0045] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. An all-fiber dual-comb laser source with continuously adjustable frequency difference, characterized in that: include: A pump laser, a first wavelength division multiplexer, an erbium-doped optical fiber, a polarization controller, a mode-locking device, an output coupler, and a second wavelength division multiplexer connected in sequence; and also comprising: a first isolator, a third wavelength division multiplexer, a second isolator, and an optical fiber delay line; The output coupler is connected to the b-port of the second wavelength division multiplexer; The c-port of the second wavelength division multiplexer is connected to the d-port of the third wavelength division multiplexer through the first isolator; The a port of the second wavelength division multiplexer is connected to the f port of the third wavelength division multiplexer through the second isolator and the optical fiber delay line in sequence; The e-port of the third wavelength division multiplexer is connected to the first wavelength division multiplexer.

2. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The pump laser adopts a 980nm semiconductor laser.

3. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The frequency division range of the first wavelength division multiplexer is 980 / 1550 nm.

4. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The mode-locking device comprises a semiconductor saturable absorption mirror, a carbon nanotube and graphene.

5. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The frequency division ranges of the second wavelength division multiplexer and the third wavelength division multiplexer are both 1530 / 1560nm; Among them, the a port, b port and c port of the second wavelength division multiplexer are 1560nm, 1530nm and 1530nm respectively, and the d port, e port and f port of the third wavelength division multiplexer are 1530nm, 1560nm and 1560nm respectively.

6. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The central wavelengths of the first isolator and the second isolator are both 1550 nm.

7. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: The central wavelength of the optical fiber delay line is 1550 nm.

8. The all-fiber dual-comb laser source with continuously adjustable frequency difference according to claim 1, characterized in that: Adopts all-fiber structure.

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