CN216773785U - 2-3 mu m broadband tuned intermediate infrared Raman soliton femtosecond laser - Google Patents

Abstract

The utility model discloses a 2-3 mu m broadband tuned intermediate infrared Raman soliton femtosecond laser, which is characterized by comprising a seed source for emitting ultrashort pulse laser with a 2 mu m waveband, a first pumping source, a second pumping source, a grating pair, a first isolator, a chalcogenide glass optical fiber jumper, a first beam combiner, a first double-cladding thulium-doped optical fiber, a second isolator, a second beam combiner, a second double-cladding thulium-doped optical fiber, a single mode optical fiber, a first plano-convex lens, a first reflector, a second reflector, a third reflector, a second plano-convex lens and a fluoride optical fiber, wherein the first isolator, the second pumping source and the grating pair are sequentially arranged along a light path emitted by the seed source; the advantages are that the output light beam has the characteristics of high power and stable and good light beam quality.

Description

2-3 mu m broadband tuned intermediate infrared Raman soliton femtosecond laser

Technical Field

The utility model relates to a mid-infrared Raman soliton femtosecond laser, in particular to a 2-3 mu m broadband tuned mid-infrared Raman soliton femtosecond laser.

Background

The tunable mid-infrared femtosecond laser has very wide application prospect in the fields of optical communication, environment detection, industrial manufacturing and the like, the wavelength range is positioned in an atmospheric absorption window, the heat radiation energy is concentrated in the waveband, and various water molecules have rich absorption spectra in the waveband; in the past decades, people utilize quantum cascade lasers, solid-state crystal lasers, optical parametric oscillators, amplifiers and the like to realize the output of tunable mid-infrared ultrashort pulse lasers, however, the above generation modes all require complex phase matching conditions and spatial light path structures, so that the stability of a laser system is poor, the practical application in complex environments is difficult to meet, and the optical fiber lasers have significant advantages in the aspects of compactness, reliability and beam quality.

The way in which lasers implement wavelength tuning functions is generally divided into three types: the first mode is to change the energy level of laser transition by changing external environment parameters such as temperature, magnetic field and the like, so as to realize the wavelength change of the laser, and the mode has high operation difficulty and is not easy to regulate and control; the second way is to use some filter devices with specific wave bands to obtain the tuning function of laser wavelength by changing the low-loss wave band of the resonant cavity, but the device has narrow tuning range and introduces loss; the third mode mainly utilizes the action mechanism of the nonlinear effect in the light wave transmission process, and the raman soliton self-frequency shift technology has obvious advantages in the aspects of wavelength tunability, stability, pulse time width and the like compared with other methods, soft glass optical fibers with low transmission loss are generally used in the middle infrared band, such as tellurate optical fibers, fluoride optical fibers and chalcogenide glass optical fibers, and the soft glass optical fibers have poor mechanical strength and low damage threshold, so that the problem of realizing the ultrashort pulse light source with wide tuning range of the middle infrared band, high power and high stability needs to be solved urgently.

Disclosure of Invention

The utility model aims to provide a 2-3 mu m broadband-tuned mid-infrared Raman soliton femtosecond laser capable of generating output light with high power and stable and good beam quality.

The technical scheme adopted by the utility model for solving the technical problems is as follows: a2-3 mu m broadband tuned mid-infrared Raman soliton femtosecond laser comprises a seed source, a first pumping source, a second pumping source, a grating pair, a first isolator, a chalcogenide glass optical fiber jumper, a first beam combiner, a first double-cladding thulium-doped optical fiber, a second isolator, a second beam combiner, a second double-cladding thulium-doped optical fiber, a single-mode optical fiber, a first plano-convex lens, a first reflector, a second reflector, a third reflector, a second plano-convex lens and a fluoride optical fiber, wherein the seed source, the first pumping source, the second pumping source, the grating pair, the first isolator, the second double-cladding thulium-doped optical fiber, the second single-mode optical fiber, the first plano-convex lens, the second reflector, the third reflector, the second plano-convex lens and the fluoride optical fiber are used for accessing a continuous laser with a central wavelength of 793nm, which is sent by the first pumping source, the other end of first beam combiner with first double-cladding thulium-doped optical fiber's one end connect, first double-cladding thulium-doped optical fiber's the other end with the second isolator link to each other, the second beam combiner with the one end that the second isolator other end links to each other be used for inserting the second pumping source send the central wavelength be 793 nm's continuous laser, the second beam combiner's the other end with the second double-cladding thulium-doped optical fiber's one end connect, the second double-cladding thulium-doped optical fiber's the other end with single mode fiber's one end connect, single mode fiber's the other end aim at first plano-convex lens's convex surface center, first plano-convex lens's the plane center transmissive light process first speculum's center after reflect to the center of second mirror, second anti-lens with received light reflection extremely the grating to the collimation and launch to the third mirror's one end in to And the third reflector reflects the received light back to the grating pair and then emits the light to the convex center of the second plano-convex lens from the grating pair, and the light transmitted by the plane center of the second plano-convex lens is focused into the fluoride optical fiber.

The first double-cladding thulium-doped optical fiber is 0.9m in length, 10 microns in fiber core diameter and 130 microns in cladding diameter, the second double-cladding thulium-doped optical fiber is 1.5m in length, 10 microns in fiber core diameter and 130 microns in cladding diameter, the fluoride optical fiber is 7.5 microns in fiber core diameter, 148 microns in cladding diameter, 0.27 in numerical aperture, 10 m in length and 1.65 microns in zero dispersion wavelength.

Compared with the prior art, the method has the advantages that the seed source adopts a fiber laser for emitting the ultrashort pulse laser with the wave band of 2 microns, the chalcogenide glass fiber is used as a pulse stretcher to stretch the pulse, the pulse is stretched through a two-stage thulium-doped fiber amplification system, the residual pump light is filtered by the single-mode fiber and then compressed through the grating pair, the output of the watt-level 2-micron femtosecond laser is obtained, the pump light is finally deflected for a certain angle and then emitted to the second plano-convex lens for coupling, the 2-micron light is efficiently coupled to the fluoride fiber, and the ultrashort pulse laser output with the 2-3-micron broadband tuning is obtained by adjusting the pump power; by analyzing the output beam quality and the far field beam intensity distribution profile, the following results were obtained: at an average output power of 352mW, the spatial energy distribution of the far-field beam is approximately Gaussian, which shows that the beam has good beam quality.

Drawings

Fig. 1 is a diagram showing an optical path structure of the present invention.

Detailed Description

The utility model is described in further detail below with reference to the accompanying examples.

A2-3 mu M broadband tuned intermediate infrared Raman soliton femtosecond laser comprises a seed source S1 for emitting ultrashort pulse laser with 2 mu M wave band, a first pump source P1, a second pump source P2, a grating pair C1, a first isolator ISO1, a chalcogenide glass fiber jumper F1, a first beam combiner Cb1, a first double-clad thulium-doped fiber D1, a second isolator ISO2, a second beam combiner Cb2, a second double-clad thulium-doped fiber D2, a single mode fiber SMF, a first plano-convex lens L1, a first reflector M1, a second reflector M2, a third reflector M3, a second plano-convex lens L2 and a fiber Z1 which are sequentially arranged along the light path emitted by the seed source S1, the first isolator ISO1, the first pump source P6853, the second pump source S1 is connected with one end of the first isolator ISO1, the other end of the chalcogenide glass fiber F5478 is connected with the first pump source S1, and the center of the first pump fiber is used for transmitting the chalcogenide laser with the wavelength of the Cb1, the other end of the first beam combiner Cb1 is connected with one end of a first double-clad thulium-doped fiber D1, the other end of the first double-clad thulium-doped fiber D1 is connected with a second isolator ISO2, one end of the second beam combiner Cb2 connected with the other end of the second isolator ISO2 is used for accessing continuous laser with the central wavelength of 793nm sent by a second pumping source P2, the other end of the second beam combiner Cb2 is connected with one end of a second double-clad thulium-doped fiber D2, the other end of the second double-clad thulium-doped fiber D2 is connected with one end of a single-mode fiber SMF, the other end of the single-mode fiber SMF is aligned with the convex center of a first plano-convex lens L1, collimated light transmitted by the plane center of the first plano-convex lens L1 passes through the center of a first reflector M1 and then is reflected to the center of a second reflector M2, the second reflector reflects the received light to a grating pair C1 and then is transmitted to the center of a third reflector M3, the light emitted from the grating pair C1 to the convex center of the second plano-convex lens L2, transmitted through the planar center of the second plano-convex lens L2, is focused into the fluoride fiber Z1.

The length of the first double-clad thulium-doped fiber D1 is 0.9m, the diameter of the fiber core is 10 μm, the diameter of the cladding is 130 μm, the length of the second double-clad thulium-doped fiber D2 is 1.5m, the diameter of the fiber core is 10 μm, the diameter of the cladding is 130 μm, the diameter of the fiber core of the fluoride fiber Z1 is 7.5 μm, the diameter of the cladding is 148 μm, the numerical aperture is 0.27, the length is 10 m, and the zero dispersion wavelength is 1.65 μm.

The specific structure and the actual working principle of the above embodiment are as follows:

the seed source S1 adopts a 2-micron wave band optical fiber laser, the maximum output power is 100mW, the central wavelength 1968 nm of the sent 2-micron wave band ultrashort pulse laser, the pulse width is 625 fs, the repetition frequency is 80 MHz, firstly, a first isolator ISO1 is connected after the seed source S1 to prevent backward reflection from influencing the stability of the seed source S1 or damaging optical devices in the amplification process, then, by utilizing the characteristic that chalcogenide glass optical fiber is in normal dispersion in the 2-micron wave band, a section of chalcogenide glass optical fiber jumper F1 is used as a pulse stretcher to stretch the pulse, then, the stretched pulse is preliminarily amplified through a pre-amplification system, the pre-amplification system adopts a forward pumping amplification mode, wherein the gain optical fiber adopts a first double-cladding thulium-doped optical fiber D1, the length is 0.9m, the fiber core diameter is 10 microns, the cladding diameter is 130 microns, the first pumping source P1 adopts a 793nm laser diode with the maximum output power of 30W, pumping light is coupled into the gain fiber through a commercial two-in-one first beam combiner Cb1, and the output power is 100mW when the pumping power is 4W; before the second-stage amplification, the amplified pulse is firstly prevented from back reflection by a second isolator ISO2, then a second double-cladding thulium-doped fiber D2 with the same model as the first double-cladding thulium-doped fiber D1 is accessed, the length of the second double-cladding thulium-doped fiber D2 is 1.5m, a second pump source P2 is a laser diode with the same model as the first pump source P1, pump light is coupled into the second double-cladding thulium-doped fiber D2 through a commercial second combiner Cb2, as the output light component contains residual pump light which is not fully absorbed, a section of single-mode fiber SMF is accessed, the residual pump light is filtered, the maximum output power reaches 1.56W along with the increase of the pump power, then the amplified pulse is collimated by a first flat convex lens L1, and the C1 is compressed by a grating to obtain the ultrashort pulse laser output with the central wavelength of 1968 nm, the pulse width of 196 fs and the repetition frequency of 80 MHz, the rms value of the long-time stability of the output facula and the laser power of the ultra-short pulse laser output by the grating pair C1 is measured to be less than 0.13%, and the fiber core transmission and the system stability of the light can be well verified; and finally, a coated N-BK7 plano-convex lens is used as a second plano-convex lens L2, the obtained compressed ultrashort pulse laser is coupled into a fluoride optical fiber Z1, the diameter of a fiber core of the fluoride optical fiber Z1 is 7.5 mu m, the diameter of a cladding is 148 mu m, the numerical aperture is 0.27, the length of the optical fiber is 10 m, the zero dispersion wavelength is 1.65 mu m, at the moment, the pump light works in an anomalous dispersion region, the Raman soliton self-frequency shift effect can be well excited, the spectrum starts to generate red shift along with the increase of the pump power, the longest wavelength reaches 3.1 mu m, and the highest output power is 352 mW.

By analyzing the output beam quality and the far field beam intensity distribution profile, the following results were obtained: at an average output power of 352mW, the spatial energy distribution of the far-field beam is approximately Gaussian, which shows that the beam has good beam quality.

Claims (2)

1. The 2-3 mu m broadband tuned intermediate infrared Raman soliton femtosecond laser is characterized by comprising a seed source, a first pumping source, a second pumping source, a grating pair and a first isolator, a chalcogenide glass optical fiber jumper, a first beam combiner, a first double-cladding thulium-doped optical fiber, a second isolator, a second beam combiner, a second double-cladding thulium-doped optical fiber, a single-mode optical fiber, a first plano-convex lens, a first reflector, a second reflector, a third reflector, a second plano-convex lens and a fluoride optical fiber, wherein the seed source, the first isolator, the second isolator and the chalcogenide glass optical fiber jumper are used for emitting ultra-short pulse laser in 2-3 mu m waveband, the first isolator, the grating pair and the first isolator, the chalcogenide glass optical fiber jumper, the second plano-convex lens and the fluoride optical fiber are sequentially arranged on a light path emitted by the seed source, the first double-cladding thulium-doped optical fiber, the second isolator, the second beam combiner, the second double-cladding thulium-doped optical fiber, the single-mode optical fiber, the first reflector, the second plano-convex lens and the fluoride optical fiber jumper are connected with one end used for accessing a continuous center wavelength of 793nm continuous laser emitted by the first pumping source Laser, the other end of first beam combiner with the one end of first double-cladding thulium-doped optical fiber connect, first double-cladding thulium-doped optical fiber the other end with the second isolator link to each other, the second beam combiner with the one end that the second isolator other end links to each other be used for the access the second pump source send the center wavelength be 793 nm's continuous laser, the other end of second beam combiner with the one end of second double-cladding thulium-doped optical fiber connect, the other end of second double-cladding thulium-doped optical fiber with single-mode optical fiber's one end connect, single-mode optical fiber's the other end aim at the convex surface center of first plano-convex lens, the plane center transmissive collimated light process of first plano-convex lens the center after reflection extremely the center of first speculum the center of second mirror, the second anti-lens with received light reflection extremely the grating to internal compression and launch extremely the third anti-reflection And the third reflector reflects the received light back to the grating pair and then emits the light to the center of the convex surface of the second plano-convex lens from the grating pair, and the light transmitted by the center of the plane of the second plano-convex lens is focused and enters the fluoride optical fiber.

2. The 2-3 μm broadband tuned mid-infrared Raman soliton femtosecond laser device according to claim 1, wherein the length of the first double-clad thulium-doped fiber is 0.9m, the diameter of the fiber core is 10 μm, the diameter of the clad is 130 μm, the length of the second double-clad thulium-doped fiber is 1.5m, the diameter of the fiber core is 10 μm, the diameter of the clad is 130 μm, the diameter of the fiber core of the fluoride fiber is 7.5 μm, the diameter of the clad is 148 μm, the numerical aperture is 0.27, the length is 10 m, and the zero dispersion wavelength is 1.65 μm.

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