All-fiber flat ultraviolet-intermediate infrared super-continuum spectrum laser based on single seed source

Abstract

The invention discloses an all-fiber flat ultraviolet-mid-infrared super-continuum spectrum laser based on a single seed source. The all-fiber flat ultraviolet-mid-infrared super-continuum spectrum laser comprises a seed laser, a two-stage ytterbium-erbium-doped fiber amplifier, a high-nonlinearity fiber NL-1550, a large-mode-field ytterbium-erbium-doped fiber amplifier, a large-mode-field ytterbium-doped fiber amplifier, a photonic crystal fiber and a passive fluoride fiber which are connected in sequence. Wherein the seed laser outputs seed pulse laser with the wavelength of 1.55 microns, and finally outputs super-continuum spectrum laser with the spectral range of 370-4500 nm and covering the ultraviolet-middle infrared band. According to the invention, an all-fiber structure is adopted, the stability and the portability are high, and the loss and the system complexity in the optical transmission process are reduced; dual-wavelength pumping is realized through a seed source, and ultra-flat spectrum output covering ultraviolet to mid-infrared is realized through cascade connection of a multi-stage amplification structure and a multi-stage nonlinear medium structure.

Description

Technical Field

[0001] The invention relates to the field of supercontinuum lasers, in particular to an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source. Background Art

[0002] The generation of supercontinuum refers to the phenomenon that the spectrum is greatly broadened under the combined effect of dispersion and nonlinear effects when a high-intensity laser pumps a nonlinear medium. The mid-infrared supercontinuum covers the characteristic absorption lines of many molecules and is widely used in frequency metrology, molecular spectroscopy, biomedicine, hyperspectral imaging, national defense and security. The all-fiber supercontinuum laser has the advantages of high spatial coherence, good stability, and portable structure. It is one of the hot spots in the international research of supercontinuum light sources. However, the existing schemes for generating supercontinuum light sources still have several defects and shortcomings:

[0003] (1) All-fiber design: Some existing supercontinuum light sources rely on free-space optical elements, resulting in low pump laser energy conversion efficiency and high system complexity and instability. The all-fiber structure can efficiently absorb and convert the energy of the pump laser, significantly improving the stability and anti-interference ability of the system.

[0004] (2) Spectral coverage: The spectral range of existing supercontinuum light sources is limited. Most of them can only cover the visible light to near-infrared band or the near-infrared to mid-infrared band, and fail to achieve full-band spectral coverage from ultraviolet to mid-infrared.

[0005] (3) Spectral flatness: Traditional technical solutions for generating supercontinuum lasers at home and abroad are mostly single-wavelength pumped nonlinear medium structures, which have obvious residual pump peaks or significant decreases in spectral brightness in certain wavelength ranges, resulting in poor overall spectral flatness.

[0006] (4) Number of seed sources: Some existing technologies use light from two seed sources, which are pre-amplified and then coupled into the optical fiber through a wavelength division multiplexer. However, in some applications that require high coherence of light, such as coherent optical communications and holographic imaging, this will have a certain impact on system performance and imaging quality. At the same time, the method of amplifying and coupling two seed sources separately may introduce more inhomogeneity and loss during the amplification process, affecting the flatness and intensity of the supercontinuum spectrum. Summary of the invention

[0007] The object of the present invention is to overcome the deficiencies of the prior art and provide an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention provides an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source, comprising a seed laser, a two-stage erbium-doped fiber amplifier, a high nonlinear fiber NL-1550, a large mode field erbium-doped fiber amplifier, a large mode field ytterbium-doped fiber amplifier, a photonic crystal fiber, and a passive fluoride fiber connected in sequence;

[0010] The seed laser outputs a 1.55 μm seed pulse laser, and the two-stage erbium-doped fiber amplifier amplifies and broadens the seed pulse laser power to generate a supercontinuum laser covering 1.5 to 2.3 μm. The supercontinuum laser pumps the highly nonlinear fiber NL-1550 to obtain a flat supercontinuum laser of 0.9 to 2.9 μm. The flat supercontinuum laser is amplified at 1.5 μm and 1.06 μm by the large mode field erbium-doped fiber amplifier and the large mode field ytterbium-doped fiber amplifier, respectively. The flat supercontinuum laser amplified at the two locations extends the short-wave cutoff edge of the supercontinuum to the ultraviolet band of 370 nm through the photonic crystal fiber, and extends the long-wave of the supercontinuum to the mid-infrared band of 4500 nm through the passive fluoride fiber, and finally outputs a supercontinuum laser covering the ultraviolet-mid-infrared band with a spectral range of 370 to 4500 nm.

[0011] Furthermore, a first optical isolator is provided between the seed laser and the two-stage erbium-doped fiber amplifier.

[0012] Further, the two-stage ytterbium-doped erbium fiber amplifier comprises a first-stage ytterbium-doped erbium fiber amplifier, a second-stage ytterbium-doped erbium fiber amplifier and a single-mode optical fiber connected in sequence;

[0013] The first-stage erbium-doped fiber amplifier comprises a first single-mode double-cladding Er 3+ / Yb 3+ doped optical fiber, a first 976 / 1550nm beam combiner, and a first 976nm multimode semiconductor laser with a maximum output power of 5W; wherein the first 976 / 1550nm beam combiner is used to couple the seed pulse laser output by the seed laser and the pump light output by the first 976nm multimode semiconductor laser to the first single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber;

[0014] The second-stage erbium-doped fiber amplifier includes a second single-mode double-cladding Er 3+ / Yb 3+doped optical fiber, a second 976 / 1550nm combiner, and a second 976nm multimode semiconductor laser with a maximum output power of 10W; wherein the second 976 / 1550nm combiner is used to couple the extended seed pulse laser output by the first-stage erbium-doped fiber amplifier and the pump light output by the second 976nm multimode semiconductor laser to the second single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber, the spectral range is extended to 1.5-2 μm;

[0015] The nonlinearity of the single-mode fiber further shifts the action frequency to 2.3 μm, generating a supercontinuum laser covering 1.5 to 2.3 μm.

[0016] Furthermore, a second optical isolator is provided between the first-stage erbium-doped fiber amplifier and the second-stage erbium-doped fiber amplifier;

[0017] A third optical isolator is arranged between the second-stage erbium-doped fiber amplifier and the single-mode optical fiber.

[0018] Furthermore, the large mode field erbium-doped fiber amplifier comprises a large mode field double-cladding Er 3+ / Yb 3+ doped optical fiber, a third 976 / 1550nm beam combiner, and two third 976nm multimode semiconductor lasers with a maximum output power of 30W; wherein the third 976 / 1550nm beam combiner is used to couple the 0.9-2.9μm flat supercontinuum laser output by the highly nonlinear optical fiber NL-1550 and the pump light output by the two third 976nm multimode semiconductor lasers to the large mode field double-clad Er 3+ / Yb 3+ Doped optical fiber amplifies the 1.5μm portion of the flat supercontinuum laser.

[0019] The large mode field ytterbium-doped fiber amplifier comprises a large mode field double-clad Yb2 fiber amplifier directly cascaded with the large mode field ytterbium-doped fiber amplifier. 3+ Doped optical fiber amplifies the 1.06μm wavelength of the flat supercontinuum laser.

[0020] Furthermore, a mode field adapter is provided between the large mode field ytterbium-doped fiber amplifier and the photonic crystal fiber.

[0021] Furthermore, the passive fluoride optical fiber is indium fluoride optical fiber.

[0022] The beneficial effects of the present invention are:

[0023] In an exemplary embodiment of the present invention, an all-fiber structure is adopted, which has high stability and portability, reduces the loss and system complexity in the optical transmission process; dual-wavelength pumping is achieved through a seed source, and an ultra-flat spectral output covering ultraviolet to mid-infrared is achieved through a cascaded multi-stage amplification structure and a multi-stage nonlinear medium structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source provided in an exemplary embodiment of the present invention;

[0025] Figure 2 It is a schematic structural diagram of an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source provided in yet another exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the directions or positional relationships indicated by "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are directions or positional relationships based on the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] See also Figure 1 , Figure 1The schematic diagram of the structure of an all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source provided in an exemplary embodiment of the present invention is shown, including a seed laser, a two-stage erbium-doped fiber amplifier (EYDFAs), a highly nonlinear fiber NL-1550, a large mode area erbium-doped fiber amplifier (LMA-EYDFA), a large mode area ytterbium-doped fiber amplifier (LMA-YDFA), a photonic crystal fiber (PCF), and a passive fluoride fiber (InF3) connected in sequence;

[0031] The seed laser outputs a 1.55 μm seed pulse laser, and the two-stage erbium-doped fiber amplifier amplifies and broadens the seed pulse laser power to generate a supercontinuum laser covering 1.5 to 2.3 μm. The supercontinuum laser pumps the highly nonlinear fiber NL-1550 to obtain a flat supercontinuum laser of 0.9 to 2.9 μm. The flat supercontinuum laser is amplified at 1.5 μm and 1.06 μm by the large mode field erbium-doped fiber amplifier and the large mode field ytterbium-doped fiber amplifier, respectively. The flat supercontinuum laser amplified at the two locations extends the short-wave cutoff edge of the supercontinuum to the ultraviolet band of 370 nm through the photonic crystal fiber, and extends the long-wave of the supercontinuum to the mid-infrared band of 4500 nm through the passive fluoride fiber, and finally outputs a supercontinuum laser covering the ultraviolet-mid-infrared band with a spectral range of 370 to 4500 nm.

[0032] Specifically, in this exemplary embodiment, the following advantages are included:

[0033] (1) All-fiber design: This exemplary embodiment adopts an all-fiber structure, which is compact, stable, and portable. Compared with the structure of spatial light transmission, the all-fiber structure can efficiently absorb and convert the energy of the pump laser, reduce the loss of optical signals during transmission, reduce the complexity and cost of the system, and improve the performance of the overall system.

[0034] (2) Spectral coverage and spectral flatness: This exemplary embodiment uses a seed source cascaded multi-stage amplifier and a multi-stage nonlinear medium structure to achieve dual-wavelength pumping. Thanks to the high peak power pulse of the pump source and the full coverage of the zero dispersion point of the nonlinear medium, this exemplary embodiment can achieve a flat spectral output in a wide wavelength range covering ultraviolet to mid-infrared, effectively improving the problem of limited spectral range and obvious residual pump peaks generated by using a single wavelength to pump the nonlinear medium in the traditional technical solution, and significantly improving the spectral flatness.

[0035] (3) Number of seed sources: This exemplary embodiment uses a single seed source to achieve time domain synchronization, and cascades active optical fibers after pre-expansion through NL-1550 optical fibers to achieve dual-wavelength synchronous amplification. Compared with the structure using two independent seed sources, this exemplary embodiment can control the time synchronization of light of different wavelengths, thereby improving the coherence and stability of the supercontinuum spectrum. In some applications that require high coherence of light, such as coherent optical communications and holographic imaging, this exemplary embodiment can provide a higher quality light source, which helps to improve system performance and imaging quality. This exemplary embodiment achieves dual-wavelength synchronous amplification through cascading active optical fibers after pre-expansion through NL-1550 optical fibers. This design can more effectively utilize the nonlinear effects of optical fibers to achieve more uniform and efficient dual-wavelength synchronous amplification.

[0036] In summary, this exemplary embodiment adopts an all-fiber structure, has high stability and portability, reduces the loss and system complexity during optical transmission, realizes dual-wavelength pumping through a seed source, and realizes ultra-flat spectral output covering ultraviolet to mid-infrared through a cascaded multi-stage amplification structure and a multi-stage nonlinear medium structure.

[0037] The following preferred exemplary embodiments will be Figure 2 Taking the example, the specific implementation methods and related principles of each component are described in detail:

[0038] More preferably, in an exemplary embodiment, a first optical isolator is provided between the seed laser and the two-stage erbium-doped fiber amplifier.

[0039] Specifically, in this exemplary embodiment, a 1550 nm nanosecond pulse laser is used as a seed source, and a first optical isolator (ISO) is used after the seed source to prevent harmful feedback light from damaging the laser.

[0040] More preferably, in an exemplary embodiment, the two-stage ytterbium-doped erbium fiber amplifier (EYDFAs) comprises a first-stage ytterbium-doped erbium fiber amplifier, a second-stage ytterbium-doped erbium fiber amplifier and a single-mode optical fiber connected in sequence;

[0041] The first-stage erbium-doped fiber amplifier comprises a first single-mode double-cladding Er 3+ / Yb 3+ doped optical fiber, a first 976 / 1550nm beam combiner, and a first 976nm multimode semiconductor laser with a maximum output power of 5W; wherein the first 976 / 1550nm beam combiner is used to couple the seed pulse laser output by the seed laser and the pump light output by the first 976nm multimode semiconductor laser to the first single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber;

[0042] The second-stage erbium-doped fiber amplifier includes a second single-mode double-cladding Er 3+ / Yb 3+ doped optical fiber, a second 976 / 1550nm combiner, and a second 976nm multimode semiconductor laser with a maximum output power of 10W; wherein the second 976 / 1550nm combiner is used to couple the extended seed pulse laser output by the first-stage erbium-doped fiber amplifier and the pump light output by the second 976nm multimode semiconductor laser to the second single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber, the spectral range is extended to 1.5-2 μm;

[0043] The nonlinearity of the single-mode fiber further shifts the action frequency to 2.3 μm, generating a supercontinuum laser covering 1.5 to 2.3 μm.

[0044] Specifically, in this exemplary embodiment, the first stage erbium-doped fiber amplifier (first EYDFA) includes a first single-mode double-clad Er 3+ / Yb 3+ doped optical fiber, the first 976 / 1550nm combiner, and the first 976nm multimode semiconductor laser (LD, Figure 2 The beam combiner is used to couple the seed pulse and pump light to Er 3+ / Yb 3+ In the doped optical fiber, LD is used to provide pump light. The structure of the second-stage erbium-doped fiber amplifier (the second EYDFA) is similar to that of the first EYDFA, but the maximum output power of the 976nm LD is 10W. In a preferred exemplary embodiment, an optical isolator (ISO) needs to be connected after each EYDFA to prevent harmful feedback light. A second optical isolator is provided between the first-stage erbium-doped fiber amplifier and the second-stage erbium-doped fiber amplifier; a third optical isolator is provided between the second-stage erbium-doped fiber amplifier and the single-mode optical fiber. The seed source is amplified in the two-stage EYDFAs, most of the pulse energy is located around 1.55μm, and the spectral range is extended to 1.5-2μm.

[0045] A single-mode fiber (SMF) is connected to the EYDFAs, and the 1550nm laser pulses amplified by the EYDFA are decomposed into multiple ultrafast pulses. In the SMF, the pulses are frequency-shifted to 2.3μm through nonlinear effects such as self-phase modulation, modulation instability and Raman soliton self-frequency shift, generating a supercontinuum laser with a spectral range of 1.5 to 2.3μm. The pulse energy distribution is relatively uniform, which is conducive to the continuous expansion of the supercontinuum spectrum.

[0046] More preferably, in an exemplary embodiment, the supercontinuum is used to pump a section of highly nonlinear optical fiber NL-1550, the ZDW of the NL-1550 optical fiber is located at 1.55 μm, and pumping in this band can produce a strong nonlinear effect. Since the pump light completely covers the zero dispersion wavelength of the NL-1550 optical fiber, the spectrum expands sharply in the long-wave direction under the action of self-phase modulation, soliton fission, and Raman soliton self-frequency shift. At the same time, due to the formation of dispersive waves, the spectrum expands sharply in the short-wave direction, and a flat 0.9-2.9 μm spectrum (i.e., a flat supercontinuum laser of 0.9-2.9 μm) is obtained.

[0047] More preferably, in an exemplary embodiment, the large mode field erbium-doped fiber amplifier comprises a large mode field double-cladding Er 3+ / Yb 3+ doped optical fiber, a third 976 / 1550nm beam combiner, and two third 976nm multimode semiconductor lasers with a maximum output power of 30W; wherein the third 976 / 1550nm beam combiner is used to couple the 0.9-2.9μm flat supercontinuum laser output by the highly nonlinear optical fiber NL-1550 and the pump light output by the two third 976nm multimode semiconductor lasers to the large mode field double-clad Er 3+ / Yb 3+ Doped optical fiber amplifies the 1.5μm portion of the flat supercontinuum laser.

[0048] The large mode field ytterbium-doped fiber amplifier comprises a large mode field double-clad Yb2 fiber amplifier directly cascaded with the large mode field ytterbium-doped fiber amplifier. 3+ Doped optical fiber amplifies the 1.06μm wavelength of the flat supercontinuum laser.

[0049] Specifically, in this exemplary embodiment, a large mode area erbium-doped fiber amplifier (LMA-EYDFA) and a large mode area ytterbium-doped fiber amplifier (LMA-YDFA) are cascaded after the NL-1550 optical fiber. The LMA-EYDFA includes a large mode area double cladding Er 3+ / Yb 3+ doped fiber, a third 976 / 1550nm combiner, and two third 976nm multimode semiconductor lasers with a maximum output power of 30W. A large mode area double-clad Yb2+ doped fiber (LMA-EYDF) is directly cascaded after the large mode area erbium doped fiber (LMA-EYDF). 3+ Doped fiber (LMA-YDF). LMA-EYDFA and LMA-YDFA amplify the pump light at 1.5μm and 1.06μm respectively.

[0050] More preferably, in an exemplary embodiment, a mode field adapter is provided between the large mode field ytterbium-doped fiber amplifier and the photonic crystal fiber.

[0051] Specifically, in this exemplary embodiment, after the LMA-YDF, a mode field adapter (MFA) is connected to match the mode field distribution of the optical fiber, thereby reducing the loss and reflection caused by mode mismatch.

[0052] More preferably, in an exemplary embodiment, a supercontinuum amplified by a multi-stage amplifier is used as a pump source to pump a section of photonic crystal fiber (PCF), the ZDW of the PCF is located near 1 μm, and through nonlinear effects such as dispersion effect and self-phase modulation, the short-wave cutoff edge of the spectrum is extended to the ultraviolet band of 370 nm;

[0053] Finally, a section of indium fluoride fiber (InF3) is cascaded. The ZDW of InF3 is located near 1.9μm. Under the induction of modulation instability, the pulse is decomposed into multiple ultrafast pulses. Through nonlinear effects such as self-phase modulation and stimulated Raman scattering, during the pulse propagation in the anomalous dispersion fiber, the spectrum becomes wider and the long-wave cutoff edge extends to the mid-infrared band of 4500nm. Finally, a supercontinuum laser covering the ultraviolet-mid-infrared band is output, with a spectral range of 370 to 4500nm.

[0054] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. An all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source, characterized by: Including the seed laser, two-stage erbium-doped fiber amplifier, high nonlinear fiber NL-1550, large mode field erbium-doped fiber amplifier, large mode field ytterbium-doped fiber amplifier, photonic crystal fiber, passive fluoride fiber connected in sequence; The seed laser outputs a 1.55 μm seed pulse laser, and the two-stage erbium-doped fiber amplifier amplifies and broadens the seed pulse laser power to generate a supercontinuum laser covering 1.5 to 2.3 μm. The supercontinuum laser pumps the highly nonlinear fiber NL-1550 to obtain a flat supercontinuum laser of 0.9 to 2.9 μm. The flat supercontinuum laser is amplified at 1.5 μm and 1.06 μm by the large mode field erbium-doped fiber amplifier and the large mode field ytterbium-doped fiber amplifier, respectively. The flat supercontinuum laser amplified at the two locations extends the short-wave cutoff edge of the supercontinuum to the ultraviolet band of 370 nm through the photonic crystal fiber, and extends the long-wave of the supercontinuum to the mid-infrared band of 4500 nm through the passive fluoride fiber, and finally outputs a supercontinuum laser covering the ultraviolet-mid-infrared band with a spectral range of 370 to 4500 nm.

2. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 1, characterized in that: A first optical isolator is arranged between the seed laser and the two-stage erbium-doped fiber amplifier.

3. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 1, characterized in that: The two-stage ytterbium-doped erbium fiber amplifier comprises a first-stage ytterbium-doped erbium fiber amplifier, a second-stage ytterbium-doped erbium fiber amplifier and a single-mode optical fiber connected in sequence; The first-stage erbium-doped fiber amplifier comprises a first single-mode double-cladding Er 3+ / Yb 3+ doped optical fiber, a first 976 / 1550nm beam combiner, and a first 976nm multimode semiconductor laser with a maximum output power of 5W; wherein the first 976 / 1550nm beam combiner is used to couple the seed pulse laser output by the seed laser and the pump light output by the first 976nm multimode semiconductor laser to the first single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber; The second-stage erbium-doped fiber amplifier includes a second single-mode double-cladding Er 3+ / Yb 3+ doped optical fiber, a second 976 / 1550nm combiner, and a second 976nm multimode semiconductor laser with a maximum output power of 10W; wherein the second 976 / 1550nm combiner is used to couple the extended seed pulse laser output by the first-stage erbium-doped fiber amplifier and the pump light output by the second 976nm multimode semiconductor laser to the second single-mode double-clad Er 3+ / Yb 3+ Doped optical fiber, the spectral range is extended to 1.5-2 μm; The nonlinearity of the single-mode fiber further shifts the action frequency to 2.3 μm, generating a supercontinuum laser covering 1.5 to 2.3 μm.

4. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 3, characterized in that: A second optical isolator is provided between the first-stage erbium-doped fiber amplifier and the second-stage erbium-doped fiber amplifier; A third optical isolator is arranged between the second-stage erbium-doped fiber amplifier and the single-mode optical fiber.

5. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 1, characterized in that: The large mode field erbium-doped fiber amplifier comprises a large mode field double cladding Er 3+ / Yb 3+ doped optical fiber, a third 976 / 1550nm beam combiner, and two third 976nm multimode semiconductor lasers with a maximum output power of 30W; wherein the third 976 / 1550nm beam combiner is used to couple the 0.9-2.9μm flat supercontinuum laser output by the highly nonlinear optical fiber NL-1550 and the pump light output by the two third 976nm multimode semiconductor lasers to the large mode field double-clad Er 3+ / Yb 3+ Doped optical fiber amplifies the 1.5μm portion of the flat supercontinuum laser. The large mode field ytterbium-doped fiber amplifier comprises a large mode field double-clad Yb2 fiber amplifier directly cascaded with the large mode field ytterbium-doped fiber amplifier. 3+ Doped optical fiber amplifies the 1.06μm wavelength of the flat supercontinuum laser.

6. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 1, characterized in that: A mode field adapter is arranged between the large mode field ytterbium-doped fiber amplifier and the photonic crystal fiber.

7. The all-fiber flat ultraviolet-mid-infrared supercontinuum laser based on a single seed source according to claim 1, characterized in that: The passive fluoride optical fiber is indium fluoride optical fiber.

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