A wavelength-tunable visible light system based on a random fiber laser

Abstract

The application discloses a wavelength-tunable visible light system based on a random fiber laser, which comprises a random fiber laser module, a first isolator, a fiber amplifier module, a second isolator, a dual-wavelength tunable Raman random laser module, a third isolator and a nonlinear frequency conversion module which are sequentially connected. The random fiber laser module is used for outputting tunable wavelength ytterbium-doped random laser. The fiber amplifier module is used for amplifying the optical power of the ytterbium-doped random laser to obtain amplified ytterbium-doped random laser. The dual-wavelength tunable Raman random laser module is used for outputting dual-wavelength tunable Raman random laser. The nonlinear frequency conversion module is used for converting the dual-wavelength tunable Raman random laser into tunable visible light random laser. The application can realize the output of wavelength-tunable visible light random laser, and there is no gap in the whole adjustment range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of laser technology, in particular to a wavelength tunable visible light system based on a random fiber laser. BACKGROUND

[0002] As a new type of laser, random fiber laser has been widely concerned and researched due to its unique physical properties and wide potential applications. Compared with traditional lasers, the random fiber laser without resonant cavity has simpler structure, higher conversion efficiency, better stability, higher reliability and lower noise. With these characteristics and advantages, the random fiber laser has wide potential applications in fiber communication, sensing, imaging and mid-infrared laser pumping source.

[0003] Although the random fiber laser has been widely concerned due to its unique properties, the wavelength of the random fiber laser based on silica fiber is limited in the near-infrared region. In order to generate visible random laser, the frequency conversion of nonlinear optics can be used to generate visible random laser by frequency doubling of random fiber laser. Through this means, green, yellow and red visible random laser can be generated by using near-infrared (1.1-1.7 μm) fiber random laser.

[0004] However, the wavelength adjustment range of the visible random laser generated by the reported fiber random laser nonlinear frequency conversion system is limited, and the visible light spectrum adjustment range exceeding 50 nm without gap cannot be realized. SUMMARY

[0005] In view of the above problems, the present application aims to provide a wavelength tunable visible light system based on a random fiber laser, which can realize an uninterrupted adjustment range of 70 nm.

[0006] The technical scheme of the present application is as follows:

[0007] A wavelength tunable visible light system based on a random fiber laser, comprising a random fiber laser module, a first isolator, a fiber amplifier module, a second isolator, a dual-wavelength tunable Raman random laser module, a third isolator and a nonlinear frequency conversion module connected in sequence.

[0008] The random fiber laser module is used to output tunable wavelength ytterbium-doped random laser.

[0009] The fiber amplifier module is used to amplify the optical power of the ytterbium-doped random laser to obtain amplified ytterbium-doped random laser.

[0010] The dual-wavelength tunable Raman random laser module is used to output dual-wavelength tunable Raman random laser.

[0011] The nonlinear frequency conversion module is used for converting the dual-wavelength tunable Raman random laser into a tunable visible light random laser.

[0012] As preferred, the random fiber laser module comprises a first pump light source and sequentially connected feedback module, first pump combiner, first ytterbium-doped fiber, and single-mode fiber; the feedback module is used for generating selectable wavelength point feedback; the first pump light source is connected with the input end of the first pump combiner.

[0013] As preferred, the feedback module comprises a fiber loop reflector, and the fiber loop reflector comprises a connected circulator and tunable filter.

[0014] As preferred, the tunable filter has a bandwidth of 0.1 nm, the tunable filter ytterbium-doped random laser has a bandwidth less than 0.3 nm, and the wavelength output is 1030 nm-1100 nm.

[0015] As preferred, the fiber amplifier module comprises sequentially connected second pump light source, second pump combiner, and second ytterbium-doped fiber; the input end of the second pump combiner is also connected with the output end of the first isolator, and the output end of the second ytterbium-doped fiber is connected with the input end of the second isolator.

[0016] As preferred, the dual-wavelength tunable Raman random laser module comprises sequentially connected dual-grating point feedback module, first wavelength division multiplexer, phosphorus-doped fiber, and second wavelength division multiplexer from the input end to the output end; the dual-grating point feedback module is used for generating selectable dual-wavelength point feedback; and the phosphorus-doped fiber is used for generating dual-wavelength Raman laser.

[0017] As preferred, the dual-grating point feedback module comprises sequentially connected first lens, polarization beam splitter, and diffraction grating from the input end to the output end; and the diffraction grating comprises first diffraction grating and second diffraction grating connected with the polarization beam splitter respectively.

[0018] As preferred, the length of the phosphorus-doped fiber is greater than 1 km; the Raman laser output by the phosphorus-doped fiber has a bandwidth of 1 nm; and the wavelength output range is 1105 nm-1160 nm and 1215 nm-1280 nm.

[0019] As preferred, the nonlinear frequency conversion module comprises sequentially connected second lens, third lens, PPLN crystal, dichroic mirror, and power meter from the input end to the output end.

[0020] As preferred, the length of the PPLN crystal is greater than 10 mm.

[0021] The present application has the following beneficial effects:

[0022] The application utilizes the tunable wavelength of the ytterbium-doped random laser output by the random fiber laser module, then amplifies the optical power through the fiber amplifier module, and then outputs the wavelength tunable Raman random laser through the tunable dual-wavelength Raman random laser module, and can be arbitrarily switched between single-wavelength or dual-wavelength modes, and finally realizes the visible light random laser with the uninterrupted adjustment range of 70nm (560nm-630nm) through the nonlinear frequency conversion module, and there is no gap in the entire adjustment range, which provides technical support for realizing compact and stable tunable visible light laser. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Figure 1 The structure diagram of the wavelength tunable visible light system based on the random fiber laser of the present application;

[0025] Figure 2 The tuning spectrum diagram of a specific embodiment 13.2THz Raman gain single-wavelength output;

[0026] Figure 3 The tuning spectrum diagram of a specific embodiment 39.9THz Raman gain peak single-wavelength output;

[0027] Figure 4 The tuning spectrum diagram of a specific embodiment two Raman gain peak corresponding wavelengths output at the same time;

[0028] Figure 5 The curve diagram of the visible light output power of a specific embodiment 565nm varying with the pump power;

[0029] Figure 6 The curve diagram of the visible light output power of a specific embodiment 595nm varying with the pump power;

[0030] Figure 7 The curve diagram of the visible light output power of a specific embodiment 615nm varying with the pump power;

[0031] Figure 8 The tunable spectrum diagram of the visible light band realized by the nonlinear frequency conversion of a specific embodiment.

[0032] The figure label: 1-random fiber laser module, 2-first isolator, 3-fiber amplifier module, 4-second isolator, 5-double wavelength tunable Raman random laser module, 6-double grating point feedback module, 7-third isolator, 8-nonlinear frequency conversion module, 9-tunable filter, 10-circulator, 11-first pump light source, 12-first pump combiner, 13-first ytterbium-doped fiber, 14-single mode fiber, 15-second pump light source, 16-second pump combiner, 17-second ytterbium-doped fiber, 18-first wavelength division multiplexer, 19-phosphorus-doped fiber, 20-second wavelength division multiplexer, 21-first lens, 22-polarization beam splitter, 23-first diffraction grating, 24-second diffraction grating, 25-second lens, 26-third lens, 27-PPLN crystal, 28-double color mirror, 29-power meter. DETAILED DESCRIPTION

[0033] The application will be further described below in conjunction with the drawings and examples. It should be noted that the examples in the present application and the technical features in the examples can be combined with each other without conflict. It should be pointed out that all the technical and scientific terms used in the present application have the same meaning as generally understood by the ordinary skilled person in the technical field to which the present application belongs. The present application discloses that the "including" or "containing" and similar words mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, and do not exclude other elements or objects.

[0034] As shown in Figure 1 The present application provides a wavelength tunable visible light system based on a random fiber laser, which comprises a random fiber laser module 1, a first isolator 2, a fiber amplifier module 3, a second isolator 4, a double wavelength tunable Raman random laser module 5, a third isolator 7, and a nonlinear frequency conversion module 8 connected in sequence.

[0035] The random fiber laser module 1 is used for outputting a tunable wavelength ytterbium-doped random laser; the fiber amplifier module 3 is used for amplifying the optical power of the ytterbium-doped random laser to obtain an amplified ytterbium-doped random laser; the double wavelength tunable Raman random laser module 5 is used for outputting a double wavelength tunable Raman random laser; and the nonlinear frequency conversion module 8 is used for converting the double wavelength tunable Raman random laser into a tunable visible light random laser.

[0036] In a specific embodiment, the random fiber laser module 1 comprises a first pump light source 11 and a feedback module, a first pump combiner 12, a first ytterbium-doped fiber 13, and a single mode fiber 14 connected in sequence; the feedback module is used for generating a selectable wavelength point feedback; and the first pump light source 11 is connected with the input end of the first pump combiner 12. In a specific embodiment, the random fiber laser module 1 comprises a first pump light source 11 and a feedback module, a first pump combiner 12, a first ytterbium-doped fiber 13, and a single mode fiber 14 connected in sequence; the feedback module is used for generating a selectable wavelength point feedback; and the first pump light source 11 is connected with the input end of the first pump combiner 12.

[0037] Optionally, the feedback module comprises a fiber loop reflector, and the fiber loop reflector comprises a circulator 10 and a tunable filter 9 connected in sequence.

[0038] Optionally, the tunable filter 9 has a bandwidth of 0.1 nm, the tunable filter generates a bandwidth of the ytterbium-doped random laser less than 0.3 nm, and the wavelength output is 1030 nm to 1100 nm. It should be noted that in the embodiment, the output laser wavelength of the random fiber laser module 1 is determined by the center wavelength of the tunable filter 9, and therefore, other parameters of the tunable filter can be selected according to the required laser wavelength.

[0039] In a specific embodiment, the fiber amplifier module 3 comprises a second pump light source 15, a second pump combiner 16, and a second ytterbium-doped fiber 17 connected in sequence. The input end of the second pump combiner 16 is further connected to the output end of the first isolator 2, and the output end of the second ytterbium-doped fiber 17 is connected to the input end of the second isolator 4.

[0040] In a specific embodiment, the dual-wavelength tunable Raman random laser module 5 comprises a dual-grating point feedback module 6, a first wavelength division multiplexer 18, a phosphorus-doped fiber 19, and a second wavelength division multiplexer 20 connected in sequence from the input end to the output end. The dual-grating point feedback module 6 is used to generate selectable dual-wavelength point feedback, and the phosphorus-doped fiber 19 is used to generate dual-wavelength Raman laser. In the embodiment, since the phosphorus-doped fiber 19 has two Raman gain peaks, single-wavelength or dual-wavelength laser output can be achieved.

[0041] Optionally, the dual-grating point feedback module 6 comprises a first lens 21, a polarization beam splitter 22, and a diffraction grating connected in sequence from the input end to the output end. The diffraction grating comprises a first diffraction grating 23 and a second diffraction grating 24 connected to the polarization beam splitter, respectively.

[0042] Optionally, the length of the phosphorus-doped fiber 19 is greater than 1 km, and the Raman laser output by the phosphorus-doped fiber 19 has a bandwidth of 1 nm and a wavelength output range of 1105 nm to 1160 nm and 1215 nm to 1280 nm. It should be noted that the length of the phosphorus-doped fiber 19 can affect the threshold, and the length used in the embodiment can reduce the threshold. When the present application is used, other lengths of phosphorus-doped fiber can be used according to the required threshold.

[0043] In one specific embodiment, the nonlinear frequency conversion module 8 comprises, sequentially connected from the input end to the output end, a second lens 25, a third lens 26, a PPLN crystal 27, a dichroic mirror 28 and a power meter 29. In this embodiment, the phase matching condition of the frequency doubling of the different-wavelength ytterbium-doped random laser is satisfied by adjusting the temperature and the polarization period of the PPLN (periodically poled lithium niobate) crystal.

[0044] Optionally, the length of the PPLN crystal 27 is greater than 10 mm. It should be noted that the length of the PPLN crystal 27 can affect the output efficiency, and the length used in this embodiment can improve the output efficiency. When the present application is used, other lengths of PPLN crystals can be used according to the required output efficiency.

[0045] It should be noted that the sub-components isolator, tunable filter, circulator, pump light source, pump combiner, ytterbium-doped fiber, single-mode fiber, wavelength division multiplexer, phosphorus-doped fiber, lens, polarization beam splitter, diffraction grating, PPLN crystal, dichroic mirror, power meter, etc. of the present application are all prior art, and the specific structures will not be described here.

[0046] In one specific embodiment using the present application, the point feedback of the selectable wavelength is constructed by the tunable filter 9 in the feedback module; the first pump light source 11 enters the first ytterbium-doped fiber 13 through the first pump combiner 12 to provide ytterbium-doped gain; the first ytterbium-doped fiber 13 combines the point feedback of the selectable wavelength and the random distributed feedback of the Rayleigh scattering in the single-mode fiber 14 to output the ytterbium-doped random laser of the tunable wavelength;

[0047] The ytterbium-doped random laser of the tunable wavelength and the second pump light source 15 enter the second ytterbium-doped fiber 17 through the second pump combiner 16 to realize the amplification of the optical power, and then the second isolator 4 is used as the pump light of the double-wavelength tunable Raman random laser module 5;

[0048] In the tunable Raman random laser module 5, the double-Raman gain peaks in the phosphorus-doped fiber 19 are respectively provided with point feedback by the double-grating point feedback module 6 composed of the first lens 21, the polarization beam splitter 22, the first diffraction grating 23 and the second diffraction grating 24, and the wavelength of the point feedback is determined by the rotation angle of the grating;

[0049] The signal light and the pump light fed back by the double-grating point feedback module 6 are input into the phosphorus-doped fiber 19 through the first wavelength division multiplexer 18, the phosphorus-doped fiber 19 provides Raman gain and random distributed feedback of Rayleigh scattering, and the double-grating point feedback module 6 forms a semi-open cavity mode, and outputs the double-wavelength tunable Raman random laser;

[0050] The tunable Raman random laser is collimated by the second lens 25, focused into the PPLN crystal 27 by the third lens 26 to realize nonlinear frequency conversion, and then transmitted to the dichroic mirror 28 to filter out the tunable visible random laser obtained by the nonlinear frequency conversion.

[0051] In the above embodiment, the point feedback is constructed by using the tunable filter 9, the wavelength tunable ytterbium-doped random laser is realized, the ytterbium-doped random laser is amplified by the optical fiber amplifier module 3, the wavelength tunable Raman random laser module 5 is based on the ytterbium-doped random laser after optical power amplification, the wavelength tunable Raman random laser output is realized by adjusting the tilt angles of the two gratings in the double-grating point feedback module 6, and the single-wavelength or double-wavelength mode can be switched arbitrarily, then the phase matching is realized by adjusting the temperature and period of the PPLN crystal, and the wavelength tunable visible random laser is realized by combining the frequency doubling in the single-wavelength mode and the sum frequency in the double-wavelength mode, and there is no gap in the entire adjustment range.

[0052] In a specific embodiment, the first pump light source 16 and the second pump light source 21 of the wavelength tunable visible light system based on the random fiber laser of the present application both generate 976nm light; the bandwidth of the tunable filter 9 is 0.1nm, the bandwidth of the tunable filter ytterbium-doped random laser is less than 0.3nm, and the wavelength output is 1030nm-1100nm; the length of the phosphorus-doped fiber 19 is 1km; and the length of the PPLN crystal 27 is 10mm. The tunable double-wavelength Raman random laser output by the embodiment is shown in the following table. Figures 2-8

[0053] From Figures 2-4 It can be seen that the feedback to different wavelengths can be changed by adjusting the angles of the two diffraction gratings in the double-grating point feedback module, so as to realize the Raman random laser output with the wavelength range of 1105-1160nm and 1215-1280nm, the relative intensity of the two wavelengths can be adjusted by adjusting the coupling effect between the diffraction grating and the optical fiber or adjusting the pump wavelength, so as to realize the single-wavelength or double-wavelength Raman random laser output.

[0054] From Figures 5-7 It can be seen that by increasing the pump power of the Raman random laser to 3W, the final visible random laser output power is close to 20mw, and there is no saturation trend, and the Raman laser output power can be further improved by reducing the fiber length, so as to improve the final visible light output power.

[0055] From Figure 8 ​It can be seen that, by using the single-wavelength laser of 1105-1160 nm or the single-wavelength random laser of 1215 nm-1280 nm for frequency doubling, in combination with the temperature and polarization period adjustment of the PPLN crystal, the tunable visible light random laser output with the wavelength range of 560-580 nm and 607.5-630 nm can be realized, if the double-wavelength random laser is used for frequency mixing, the visible light output of 580 nm-608 nm can be realized, and by combining the two, the visible light random laser output of 560 nm-630 nm (a total of 70 nm) can be realized, and there is no gap in the entire adjustment range, and the adjustment range contains green, yellow and red three colors.

[0056] In summary, the present application can realize the visible light random laser with tunable output wavelength, the entire adjustment range can reach 70 nm and there is no gap in the entire adjustment range. Compared with the prior art, the present application has significant progress.

[0057] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with the preferred embodiment, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. A wavelength-tunable visible light system based on a random fiber laser, characterized by, The random fiber laser module, the first isolator, the fiber amplifier module, the second isolator, the double-wavelength tunable Raman random laser module, the third isolator and the nonlinear frequency conversion module are sequentially connected. The random fiber laser module is used for outputting tunable wavelength ytterbium-doped random laser. The fiber amplifier module is used for amplifying the optical power of the ytterbium-doped random laser, obtaining amplified ytterbium-doped random laser, and serving as pump light of the double-wavelength tunable Raman random laser module through the second isolator. The double-wavelength tunable Raman random laser module is used for outputting double-wavelength tunable Raman random laser, and includes a double-grating-point feedback module, a first wavelength division multiplexer, a phosphorus-doped fiber and a second wavelength division multiplexer which are sequentially connected from an input end to an output end. The nonlinear frequency conversion module is used for converting the double-wavelength tunable Raman random laser into tunable visible light random laser, and includes a second lens, a third lens, a PPLN crystal, a dichroic mirror and a power meter which are sequentially connected from an input end to an output end.

2. The random-fiber-laser-based wavelength-tunable visible light system of claim 1, wherein, The random fiber laser module includes a first pump light source and a feedback module, a first pump combiner, a first ytterbium-doped fiber and a single-mode fiber which are sequentially connected.

3. The random-fiber-laser-based wavelength-tunable visible light system of claim 2, wherein, The feedback module includes a fiber loop reflector which includes a circulator and a tunable filter.

4. The random-fiber-laser-based wavelength-tunable visible light system of claim 3, wherein, The bandwidth of the tunable filter is 0.1 nm, the bandwidth of the tunable filter ytterbium-doped random laser is less than 0.3 nm, and the wavelength output is 1030 nm to 1100 nm.

5. The random fiber laser based wavelength-tunable visible light system of claim 1, wherein, The fiber amplifier module includes a second pump light source, a second pump combiner and a second ytterbium-doped fiber which are sequentially connected.

6. The random fiber laser based wavelength-tunable visible light system of claim 1, wherein, The double-grating-point feedback module includes a first lens, a polarization beam splitter and a diffraction grating which are sequentially connected from an input end to an output end.

7. The random-fiber-laser-based wavelength-tunable visible light system of claim 1, wherein, The length of the phosphorus-doped fiber is greater than 1 km, the bandwidth of the Raman laser output by the phosphorus-doped fiber is 1 nm, and the wavelength output range is 1105 nm to 1160 nm and 1215 nm to 1280 nm.

8. The random-fiber-laser-based wavelength-tunable visible light system of claim 1, wherein, The length of the PPLN crystal is greater than 10 mm.

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