Raman fiber laser

Abstract

The utility model relates to a Raman fiber laser, and the Raman fiber laser comprises a pumping source which is configured to generate pumping light; the Raman seed light generation unit is configured to convert the pump light into wavelength-tunable Raman seed light; the Raman laser generation unit is configured to perform power amplification on a part of light in the Raman seed light and convert the other part of light in the Raman seed light into Raman laser by using the amplified Raman seed light, so that the wavelength tuning function and high light-to-light conversion efficiency of the Raman fiber laser can be realized; good application prospects are realized.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a Raman fiber laser. Background Art

[0002] Fiber lasers have the advantages of high beam quality, small size, high efficiency, simple structure, and easy maintenance, and have been widely used in military and civilian fields. Fiber lasers based on rare earth doping can already achieve a wider wavelength output, but the wavelength of the laser they emit is limited by the emission cross-section of rare earth ions, and they cannot emit lasers in special bands such as 1.1-1.35μm, 1.6-1.75μm, 2.1-2.3μm, etc. Raman fiber lasers can achieve wavelength conversion based on the Raman effect, that is, the nonlinear effect of laser transmission in optical fiber can be used to expand the wavelength of the laser, so as to obtain the required wavelength within the Raman gain bandwidth.

[0003] However, the Raman fiber laser in the prior art has the problems of low optical-to-optical conversion efficiency and no wavelength tuning function. Utility Model Content

[0004] The purpose of the present application is to provide a Raman fiber laser to realize the wavelength tuning function of the Raman fiber laser and improve the optical-to-optical conversion efficiency of the Raman fiber laser.

[0005] An embodiment of the present application provides a Raman fiber laser, which includes: a pump source configured to generate pump light; a Raman seed light generating unit configured to convert the pump light into a Raman seed light with tunable wavelength; and a Raman laser generating unit configured to amplify a portion of the Raman seed light and convert another portion of the Raman seed light into Raman laser using the amplified Raman seed light.

[0006] Among them, the Raman seed light generating unit includes a wavelength division multiplexer, a first isolator, a first filter, a first coupler and a first gain fiber. The wavelength division multiplexer, the first isolator, the first filter, the first coupler and the first gain fiber are connected in series in sequence to form a ring cavity structure. The wavelength division multiplexer is configured to inject pump light into the ring cavity structure, and the first coupler is configured to output a part of the laser in the ring cavity structure as Raman seed light.

[0007] Wherein, the first filter is a tunable filter.

[0008] Wherein, the first gain optical fiber comprises rare-earth doped optical fiber.

[0009] The Raman laser generating unit includes a second isolator, a second coupler and an optical amplifier connected in series in sequence. The transmission direction of light in the Raman laser generating unit is along the direction of the second isolator, the second coupler and the optical amplifier in sequence, and the optical amplifier is configured to amplify a part of the Raman seed light, and use the amplified Raman seed light to convert another part of the Raman seed light into Raman laser.

[0010] The optical amplifier includes a doped gain fiber and a Raman gain fiber connected in series, and the transmission direction of light in the optical amplifier is along the direction of the doped gain fiber and the Raman gain fiber in sequence.

[0011] The optical amplifier further comprises a cladding light filter, which is connected in series between the doped gain optical fiber and the Raman gain optical fiber.

[0012] Wherein, the doped gain optical fiber is a rare earth doped optical fiber.

[0013] The Raman laser generating unit further includes a second filter, which is connected to the optical amplifier and configured to filter out the pump light contained in the light output by the optical amplifier.

[0014] There are multiple optical amplifiers, and the multiple optical amplifiers are cascaded.

[0015] The Raman fiber laser provided in the present application includes a pump source, a Raman seed light generating unit and a Raman laser generating unit, wherein the pump source is configured to generate pump light, the Raman seed light generating unit is configured to convert the pump light into a Raman seed light with tunable wavelength, and the Raman laser generating unit is configured to amplify a part of the Raman seed light, and use the amplified Raman seed light to convert another part of the Raman seed light into Raman laser, thereby realizing the wavelength tuning function and high light-to-light conversion efficiency of the Raman fiber laser, and having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0017] Figure 1 is a schematic diagram of the structure of a Raman fiber laser provided in an embodiment of the present application;

[0018] Figure 2 is a schematic structural diagram of a Raman seed light generating unit provided in an embodiment of the present application;

[0019] Figure 3 It is a schematic diagram of the structure of the Raman laser generating unit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0021] In addition, when describing the structure of a component, when a layer or a region is referred to as being "on" or "above" another layer or another region, it may mean being directly above the other layer or another region, or having other layers or regions between it and the other layer or another region. Moreover, if the component is turned over, the layer or a region will be "under" or "below" the other layer or another region. In addition, the features, structures, or characteristics described below may be combined in any suitable manner in one or more embodiments.

[0022] Fiber lasers have the advantages of high beam quality, small size, high efficiency, simple structure, and easy maintenance. They have been widely used in military and civilian fields.

[0023] Rare earth-doped fiber lasers can already achieve a wider wavelength output, but the wavelength of the laser they emit is limited by the emission cross-section of the rare earth ions and cannot emit lasers in special bands such as 1.1-1.35μm, 1.6-1.75μm, and 2.1-2.3μm.

[0024] Raman fiber lasers can achieve wavelength conversion based on the Raman effect, that is, the nonlinear effect of laser transmission in optical fiber can be used to expand the wavelength of the laser, so as to obtain the required wavelength within the Raman gain bandwidth. This can make up for the deficiency of rare earth-doped fiber lasers that cannot emit lasers in special bands.

[0025] However, the Raman fiber laser in the prior art has the problems of low optical-to-optical conversion efficiency and no wavelength tuning function.

[0026] In view of the above problems, an embodiment of the present application provides a Raman fiber laser, which includes a pump source, a Raman seed light generating unit and a Raman laser generating unit, wherein the pump source is configured to generate pump light, the Raman seed light generating unit is configured to convert the pump light into a Raman seed light with tunable wavelength, and the Raman laser generating unit is configured to amplify a part of the Raman seed light, and use the amplified Raman seed light to convert another part of the Raman seed light into Raman laser, thereby realizing the wavelength tuning function and high light-to-light conversion efficiency of the Raman fiber laser, and having good application prospects.

[0027] The following is a detailed description with reference to specific embodiments. It should be noted that the serial numbers of the following embodiments are not intended to limit the preferred order of the embodiments.

[0028] See also Figure 1 , Figure 1 Schematic diagram of the structure of the Raman fiber laser provided in the embodiment of the present application. Figure 1 As shown, the Raman fiber laser 10 may include a pump source 11, a Raman seed light generating unit 12, and a Raman laser generating unit 13. The pump source 11 is configured to generate pump light, and the Raman seed light generating unit 12 is configured to convert the pump light into a wavelength-tunable Raman seed light. The Raman laser generating unit 13 is configured to convert a portion of the Raman seed light into Raman laser light, and to power-amplify another portion of the Raman seed light, thereby realizing the wavelength tuning function of the Raman fiber laser 10 and high-power Raman laser output.

[0029] In some examples, the pump source 11 may be a semiconductor laser (LD).

[0030] In some embodiments, Figure 2 As shown, the Raman seed light generating unit 12 may include a wavelength division multiplexer 121, a first isolator 122, a first filter 123, a first coupler 124 and a first gain fiber 125. Furthermore, the wavelength division multiplexer 121, the first isolator 122, the first filter 123, the first coupler 124 and the first gain fiber 125 are sequentially connected in series to form a ring cavity structure.

[0031] The wavelength division multiplexer 121 may be configured to inject the pump light output by the pump source 11 into the ring cavity structure. Specifically, the pump source 11 may inject the pump light into the ring cavity structure through the pump light input port 121 a of the wavelength division multiplexer 121 .

[0032] The first coupler 124 can be configured to output a portion of the laser light in the ring cavity structure as Raman seed light. Specifically, the first coupler 124 can output a portion (eg, 50%) of the laser light oscillated in the ring cavity structure as Raman seed light through its output end 124a.

[0033] The first isolator 122 can maintain unidirectional propagation of laser light in the above-mentioned ring cavity structure. In some examples, the transmission direction of light in the above-mentioned ring cavity structure can be a circular direction from the wavelength division multiplexer 121 to the first isolator 122 to the first filter 123 to the first coupler 124 to the first gain fiber 125 to the wavelength division multiplexer 121.

[0034] The first filter 123 may be a tunable filter to achieve tunability of the laser wavelength in the ring cavity structure.

[0035] The first gain fiber 125 is used to absorb the pump light and emit laser. Specifically, the first gain fiber 125 may include a rare earth doped fiber, for example, a rare earth doped fiber. The rare earth doped in the rare earth doped fiber may be ytterbium, erbium, thulium, holmium, praseodymium, neodymium, germanium, europium, dysprosium or other rare earths.

[0036] Specifically, during the use of the above-mentioned Raman fiber laser 10, the pump light generated by the pump source 11 is coupled into the ring cavity structure through the wavelength division multiplexer 121, and after reaching the first gain fiber 125, it will be absorbed by the rare earth ions doped in the first gain fiber 125. The rare earth ions will undergo energy level transitions due to the absorption of the energy of the photons, thereby generating laser.

[0037] In some embodiments, Figure 3 As shown, the Raman laser generating unit 13 may include a second isolator 131, a second coupler 132 and an optical amplifier 133 connected in series in sequence. In addition, the transmission direction of light in the Raman laser generating unit 13 is sequentially along the second isolator 131, the second coupler 132 and the optical amplifier 133, wherein the optical amplifier 133 is configured to amplify a portion of the Raman seed light output by the Raman seed light generating unit 12, and use the amplified Raman seed light to convert another portion of the Raman seed light output by the Raman seed light generating unit 12 into Raman laser light.

[0038] Furthermore, it should be noted that in the above-mentioned Raman laser generating unit 13, after the Raman seed light passes through the optical amplifier 133, a part of the light beam is amplified, and the other part of the light beam is converted into a Raman light beam. This optical structure avoids the problem that high-power laser cannot be injected due to the low threshold power that the optical device can withstand, and thus can overcome the problem of low Raman laser output of existing Raman fiber lasers.

[0039] Specifically, in the above-mentioned Raman laser generating unit 13, the second isolator 132 can maintain the unidirectional propagation of the laser and prevent the above-mentioned Raman seed light generating unit 12 from being damaged by the returning light. The second coupler 132 can couple the Raman seed light passing through the second isolator 132 into the optical amplifier 133, so that a part of the Raman seed light is amplified by the optical amplifier 133, and another part of the Raman seed light is converted into Raman laser by the optical amplifier 133.

[0040] In some examples, the second coupler 132 may be a (6+1) coupler.

[0041] In some embodiments, Figure 3As shown, in the above-mentioned Raman laser generating unit 13, the optical amplifier 133 may include a doped gain fiber 1331 and a Raman gain fiber 1333 connected in series, and the transmission direction of the light in the optical amplifier 133 is sequentially along the direction of the doped gain fiber 1331 and the Raman gain fiber 1333. Among them, the doped gain fiber 1331 can be configured to amplify a part of the Raman seed light output by the above-mentioned Raman seed light generating unit 12 to meet the demand for high-power Raman seed light. The Raman gain fiber 1333 can be configured to absorb the Raman seed light amplified by the doped gain fiber 1331, and convert another part of the Raman seed light output by the above-mentioned Raman seed light generating unit 12 into Raman laser.

[0042] In some examples, the doped gain fiber 1331 may be a rare-earth doped fiber. The Raman gain fiber 1333 may be a quartz fiber or a fluoride fiber.

[0043] In some embodiments, Figure 3 As shown, the above-mentioned optical amplifier 133 can also include a cladding light filter (CMS) 1332. The cladding light filter 1332 is connected in series between the doped gain fiber 1331 and the Raman gain fiber 1333. It can prevent the cladding light propagating along the laser output direction from damaging subsequent devices and is conducive to purer laser output.

[0044] In some embodiments, Figure 3 As shown, the Raman laser generating unit 13 may further include a second filter 134 , which is connected to the optical amplifier 133 and may be configured to filter out the pump light contained in the light output by the optical amplifier 133 to ensure the purity of the output laser.

[0045] In some embodiments, there may be multiple optical amplifiers 133 , and the multiple optical amplifiers 133 are cascaded to form a multi-stage Raman amplification structure to achieve multi-stage Raman amplification of Raman seed light.

[0046] As can be seen from the above, the Raman fiber laser provided in this embodiment includes a pump source, a Raman seed light generating unit and a Raman laser generating unit, wherein the pump source is configured to generate pump light, the Raman seed light generating unit is configured to convert the pump light into a Raman seed light with tunable wavelength, and the Raman laser generating unit is configured to power amplify a part of the Raman seed light, and use the amplified Raman seed light to convert another part of the Raman seed light into Raman laser, thereby achieving high light-to-light conversion efficiency and wavelength tuning function of the Raman fiber laser, and having good application prospects.

[0047] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A Raman fiber laser, characterized in that: include: a pump source configured to generate pump light; A Raman seed light generating unit, configured to convert the pump light into a Raman seed light with tunable wavelength; The Raman laser generating unit is configured to amplify a portion of the Raman seed light, and convert another portion of the Raman seed light into Raman laser light by using the amplified Raman seed light.

2. The Raman fiber laser according to claim 1, characterized in that: The Raman seed light generating unit comprises a wavelength division multiplexer, a first isolator, a first filter, a first coupler and a first gain fiber. The wavelength division multiplexer, the first isolator, the first filter, the first coupler and the first gain fiber are sequentially connected in series to form a ring cavity structure. The wavelength division multiplexer is configured to inject the pump light into the ring cavity structure, and the first coupler is configured to output a part of the laser in the ring cavity structure as the Raman seed light.

3. The Raman fiber laser according to claim 2, characterized in that: The first filter is a tunable filter.

4. The Raman fiber laser according to claim 2, characterized in that: The first gain fiber includes a rare-earth doped fiber.

5. The Raman fiber laser according to claim 1, characterized in that: The Raman laser generating unit comprises a second isolator, a second coupler and an optical amplifier which are connected in series in sequence. The transmission direction of light in the Raman laser generating unit is in the direction of the second isolator, the second coupler and the optical amplifier in sequence, and the optical amplifier is configured to amplify a part of the Raman seed light, and use the amplified Raman seed light to convert another part of the Raman seed light into Raman laser.

6. The Raman fiber laser according to claim 5, characterized in that: The optical amplifier comprises a doped gain optical fiber and a Raman gain optical fiber connected in series, and the transmission direction of light in the optical amplifier is sequentially along the doped gain optical fiber and the Raman gain optical fiber.

7. The Raman fiber laser according to claim 6, characterized in that: The optical amplifier further comprises a cladding light filter, and the cladding light filter is serially connected between the doped gain optical fiber and the Raman gain optical fiber.

8. The Raman fiber laser according to claim 6, characterized in that: The doped gain optical fiber is a rare earth doped optical fiber.

9. The Raman fiber laser according to claim 5, characterized in that: The Raman laser generating unit further includes a second filter, which is connected to the optical amplifier and configured to filter out the pump light contained in the light output by the optical amplifier.

10. The Raman fiber laser according to claim 5, characterized in that: There are multiple optical amplifiers, and the multiple optical amplifiers are cascaded.

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