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

A 2～3μm Broadband Tuned Mid-Infrared Raman Soliton Femtosecond Laser

technical field

The utility model relates to a mid-infrared Raman soliton femtosecond laser, in particular to a mid-infrared Raman soliton femtosecond laser with 2-3 μm broadband tuning.

Background technique

The tunable mid-infrared femtosecond laser has a very broad application prospect in the fields of optical communication, environmental detection, and industrial manufacturing, and the wavelength range is located in the absorption window of the atmosphere, the thermal radiation energy is concentrated in this band, and a variety of water molecules are in this wavelength range. The wavelength band has a rich absorption spectrum; in the past few decades, people have used quantum cascade lasers, solid-state crystal lasers, optical parametric oscillators, and amplifiers to realize the output of tunable mid-infrared ultrashort pulse lasers. However, the above generation methods all require The complex phase matching conditions and spatial optical path structure result in poor stability of the laser system, making it difficult to meet practical applications in complex environments, while fiber lasers have significant advantages in terms of compactness, reliability and beam quality.

There are usually three ways to realize the wavelength tuning function of lasers: the first way is to change the energy level of laser transition by changing external environmental parameters such as temperature and magnetic field to realize the wavelength change of the laser. This method is difficult to operate and not easy to operate. control; the second way is to use some filter devices in a specific band to obtain the tuning function of the laser wavelength by changing the low-loss band of the resonator, but this device has a narrow tuning range and introduces loss; the third way The main method is to use the mechanism of nonlinear effects in the light wave transmission process. The Raman soliton self-frequency shift technology has obvious advantages compared with other methods in terms of wavelength tunability, stability and pulse time width. In the infrared band, soft glass fibers with low transmission loss are generally used, such as tellurate fibers, fluoride fibers and chalcogenide glass fibers, while soft glass fibers have poor mechanical strength and low damage thresholds, so they can achieve wide-range tuning in the mid-infrared band. The problem of ultrashort pulsed light source with high power and high stability needs to be solved urgently.

SUMMARY OF THE INVENTION

The technical problem to be solved by the utility model is to provide a mid-infrared Raman soliton femtosecond laser with 2-3 μm broadband tuning capable of generating high-power output light with stable and good beam quality.

The technical scheme adopted by the utility model to solve the above technical problems is as follows: a mid-infrared Raman soliton femtosecond laser with 2-3 μm broadband tuning, comprising a seed source for emitting an ultra-short pulse laser in a 2 μm waveband, a first pumping source, a second pump source, a grating pair, a first isolator, a chalcogenide glass fiber jumper, a first beam combiner, a first double-clad thulium-doped fiber, Second isolator, second beam combiner, second double-clad thulium-doped fiber, single-mode fiber, first plano-convex lens, first mirror, second mirror, third mirror, second plano-convex lens, and fluorine a compound fiber, the seed source is connected to one end of the first isolator, the other end of the first isolator is connected to one end of the chalcogenide glass fiber jumper, and the first combined One end of the beam device connected to the other end of the chalcogenide glass fiber jumper is used to connect to the continuous laser with the center wavelength of 793 nm sent by the first pump source, and the other end of the first beam combiner is used. One end is connected with one end of the first double cladding thulium doped fiber, the other end of the first double cladding thulium doped fiber is connected with the second isolator, and the second beam combiner is connected to the second isolator. The end connected to the other end of the second isolator is used to connect to the continuous laser with a center wavelength of 793 nm sent by the second pump source, and the other end of the second beam combiner is connected to the first One end of the two double-clad thulium-doped fibers is connected, the other end of the second double-clad thulium-doped fiber is connected to one end of the single-mode fiber, and the other end of the single-mode fiber is aligned with the The center of the convex surface of the first plano-convex lens, the collimated light transmitted by the center of the plane of the first plano-convex lens passes through the center of the first reflecting mirror and is then reflected to the center of the second reflecting mirror, and the The second mirror lens reflects the received light into the grating pair and compresses it and emits it to the center of the third reflector, and the third reflector reflects the received light back to the grating pair, from the The grating pair is emitted to the center of the convex surface of the second plano-convex lens, and the light transmitted by the center of the plane of the second plano-convex lens is focused into the fluoride fiber.

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

Compared with the prior art, the advantage of the utility model is that the seed source adopts a fiber laser for emitting ultra-short pulse laser in the 2 μm band, and the chalcogenide glass fiber is used as a pulse stretcher to widen the pulse, and the two-stage thulium-doped fiber is amplified. After the system, the residual pump light is filtered by a single-mode fiber and then compressed by a grating pair to obtain a watt-level 2μm femtosecond laser output, which is finally deflected at a certain angle and emitted to the second plano-convex lens for coupling. The light is efficiently coupled into the fluoride fiber, and by adjusting the pump power, a 2~3μm broadband tuned ultrashort pulse laser output is obtained; by analyzing the output beam quality and far-field beam intensity distribution profile, the results are as follows: At the average output power When it is 352 mW, the spatial energy distribution of the far-field beam is nearly Gaussian, indicating that it has good beam quality.

Description of drawings

Fig. 1 is the optical path structure diagram of the utility model.

Detailed ways

The present utility model will be further described in detail below with reference to the embodiments of the accompanying drawings.

A 2-3 μm broadband tuned mid-infrared Raman soliton femtosecond laser, comprising a seed source S1 for emitting ultra-short pulse laser in a 2 μm band, a first pump source P1, a second pump source P2, and a grating pair C1 , the first isolator ISO1, the chalcogenide glass fiber jumper F1, the first combiner Cb1, the first double-clad thulium-doped fiber D1, the second isolator ISO2, the second The beam combiner Cb2, the second double-clad thulium-doped fiber D2, the single-mode fiber SMF, the first plano-convex lens L1, the first reflector M1, the second reflector M2, the third reflector M3, the second plano-convex lens L2 and Fluoride fiber Z1, the seed source S1 is connected to one end of the first isolator ISO1, the other end of the first isolator ISO1 is connected to one end of the chalcogenide glass fiber jumper F1, and the first combiner Cb1 is connected to the chalcogenide glass fiber jumper One end connected to the other end of the line F1 is used to connect to the continuous laser with a center wavelength of 793 nm sent by the first pump source P1, and the other end of the first beam combiner Cb1 is connected to one end of the first double-clad thulium-doped fiber D1 , the other end of the first double-clad thulium-doped fiber D1 is connected to the second isolator ISO2, and the other end of the second beam combiner Cb2 connected to the other end of the second isolator ISO2 is used to access the signal sent by the second pump source P2 A continuous laser with a center wavelength of 793 nm, the other end of the second beam combiner Cb2 is connected to one end of the second double-clad thulium-doped fiber D2, and the other end of the second double-clad thulium-doped fiber D2 is connected to one end of the single-mode fiber SMF Connection, the other end of the single-mode fiber SMF is aligned with the center of the convex surface of the first plano-convex lens L1, and the collimated light transmitted by the center of the plane of the first plano-convex lens L1 passes through the center of the first reflector M1 and is then reflected to the second reflector M2. At the center, the second mirror reflects the received light into the grating pair C1, compresses it and emits it to the center of the third mirror M3, the third mirror M3 reflects the received light back to the grating pair C1, Emitted to the center of the convex surface of the second plano-convex lens L2, the light transmitted from the center of the plane 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 0.9 m, the core diameter is 10 μm, and the cladding diameter is 130 μm. With a diameter of 130 μm, the fluoride fiber Z1 has a core diameter of 7.5 μm, a cladding diameter of 148 μm, a numerical aperture of 0.27, a length of 10 m, and a zero-dispersion wavelength of 1.65 μm.

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

The seed source S1 uses a 2μm band fiber laser with a maximum output power of 100 mW. The center wavelength of the 2μm band ultra-short pulse laser is 1968 nm, the pulse width is 625 fs, and the repetition frequency is 80 MHz. Then connect the first isolator ISO1 to prevent retroreflection from affecting the stability of the seed source S1 or damage the optical device during the amplification process, and then use the chalcogenide glass fiber to have normal dispersion in the 2μm band. F1 acts as a pulse stretcher to stretch the pulse, and then passes through a pre-amplification system to initially amplify the stretched pulse. The pre-amplification system adopts the forward pumping amplification method, and the gain fiber selects the first double-clad thulium-doped fiber D1. The length is 0.9 m, the core diameter is 10 μm, and the cladding diameter is 130 μm. The first pump source P1 uses a 793 nm laser diode with a maximum output power of 30 W, and the pump is pumped through a commercial two-in-one first beam combiner Cb1. The pump light is coupled into the gain fiber. When the pump power is 4W, the output power is 100mW; before the second stage of amplification, the second isolator ISO2 is used to prevent back reflection, and then connected to the first double-clad thulium-doped fiber D1 model The same second double cladding thulium doped fiber D2, the length of the second double cladding thulium doped fiber D2 is 1.5m, the second pump source P2 is a laser diode of the same type as the first pump source P1, and the pump light It is coupled into the second double-clad thulium-doped fiber D2 through a commercial two-in-one second beam combiner Cb2. Since there is residual pump light that is not fully absorbed in the output light component, a section of single-mode fiber SMF is connected. , filter the residual pump light, with the increase of pump power, the maximum output power reaches 1.56W, then the amplified pulse is collimated by the first plano-convex lens L1, and the center wavelength is 1968 after the grating compresses C1 The ultra-short pulse laser output of nm, pulse width is 196 fs, and repetition frequency is 80 MHz. At this time, it is measured that the long-term stability rms value of the output spot and laser power of the ultra-short pulse laser output by the grating to C1 is less than 0.13%. It is verified that the light can transmit well in the fiber core and the stability of the system; finally, a coated N-BK7 plano-convex lens is used as the second plano-convex lens L2, and the obtained compressed ultrashort pulse laser is coupled into the fluoride fiber Z1 , the core diameter of the fluoride fiber Z1 is 7.5 μm, the cladding diameter is 148 μm, the numerical aperture is 0.27, the fiber length is 10 m, and the zero dispersion wavelength is 1.65 μm. At this time, the pump light works in the anomalous dispersion region, which can be very good The excitation Raman soliton self-frequency-shift effect of , with the increase of pump power, the spectrum begins to red-shift, the longest wavelength reaches 3.1μm, and the highest output power is 352mW.

By analyzing the output beam quality and far-field beam intensity distribution profile, the results are as follows: when the average output power is 352 mW, the far-field beam spatial energy distribution is nearly Gaussian, indicating that it 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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