CN118099911A - High-power 3.5 mu m mode-locked pulse laser source - Google Patents

High-power 3.5 mu m mode-locked pulse laser source Download PDF

Info

Publication number
CN118099911A
CN118099911A CN202410245844.6A CN202410245844A CN118099911A CN 118099911 A CN118099911 A CN 118099911A CN 202410245844 A CN202410245844 A CN 202410245844A CN 118099911 A CN118099911 A CN 118099911A
Authority
CN
China
Prior art keywords
laser
mode
lens
source
pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202410245844.6A
Other languages
Chinese (zh)
Inventor
李剑峰
陈俊生
钟文博
赵鑫生
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Electronic Science and Technology of China
Original Assignee
University of Electronic Science and Technology of China
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Electronic Science and Technology of China filed Critical University of Electronic Science and Technology of China
Priority to CN202410245844.6A priority Critical patent/CN118099911A/en
Publication of CN118099911A publication Critical patent/CN118099911A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06708—Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/102—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation
    • H01S3/1022—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the active medium, e.g. by controlling the processes or apparatus for excitation by controlling the optical pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1106—Mode locking
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/17—Solid materials amorphous, e.g. glass
    • H01S3/173—Solid materials amorphous, e.g. glass fluoride glass, e.g. fluorozirconate or ZBLAN [ ZrF4-BaF2-LaF3-AlF3-NaF]

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

The invention discloses a high-power 3.5 mu m mode-locked pulse laser source, which comprises a super-continuous pumping source, an InF optical fiber, a first lens, a dichroic mirror, an off-axis Er 3+ fluoride optical fiber, a cladding pumping source connected to the dichroic mirror and a second lens connected between the dichroic mirror and the cladding pumping source, wherein the super-continuous pumping source, the InF optical fiber, the first lens, the dichroic mirror, the off-axis Er 3+ fluoride optical fiber and the cladding pumping source are sequentially connected. When the invention is applied, high-power mode locking pulse output of 3.5 mu m can be obtained, meanwhile, the structural complexity of the laser is greatly reduced due to the linear cavity structure, the system stability during high-power output is ensured, and the applicability of the laser is improved.

Description

High-power 3.5 mu m mode-locked pulse laser source
Technical Field
The invention relates to the technical field of mid-infrared lasers, in particular to a high-power 3.5 mu m mode-locked pulse laser source.
Background
The mid-infrared band of 3-5 μm is a very specific region of the electromagnetic spectrum that covers not only the intrinsic absorption peaks of numerous molecules and atoms, but also one of the atmospheric transparent windows. The ultra-short pulse laser with the wave band has great application prospect in a plurality of fields such as communication, biomedical treatment, national defense and the like.
Since the infrared laser in the 3-5 μm wave band overlaps with the important atmospheric transmission window, the wave band laser has lower attenuation when propagating in the atmosphere, so the further development of coherent optical communication and free space communication depend on high-quality 3-5 μm ultrashort pulse lasers. In biomedical applications, the photomechanical action of ultrashort pulsed lasers can produce better ablation boundaries (i.e., less carbonization and minimal cell death) in various soft tissues than continuous lasers in the 3 μm band, and can ablate lipid-rich tissues, bone, and protein-containing tissues with minimal collateral damage. In the field of national defense, an ultrashort pulse source can transmit longer distances, the limit of atmospheric transmission critical power is smaller, and the ultrashort pulse source has great potential in a high-peak power directional weapon system; in addition, the sensitivity and anti-interference performance of the mid-infrared band guided missile are continuously enhanced, so that the mid-infrared band guided missile has a larger range, the band detector can be used for effective interference and complete blindness, and the threat of fourth-generation gaze imaging guidance is restrained.
At present, in the fiber laser, the method for generating 3-5 mu m ultrashort pulse laser mainly has two main types, one type is to perform mode locking modulation on continuous laser generated based on a rare earth ion doped fiber direct laser method. The other type is Raman soliton self-frequency shift, and Raman scattering in pulses and continuous wavelength red shift are realized by utilizing Raman effect in the optical fiber, so that wavelength tuning output in the wave band is realized. However, the seed source of the laser based on Raman soliton self-frequency shift is usually a rare earth ion doped fiber laser with different output wavelengths, and the final output power is low, tuning is inconvenient and application prospect is poor. The ultra-short pulse laser generated by the direct laser method based on the rare earth ion doped optical fiber can theoretically obtain extremely high peak power and larger average power. In the 3-5 μm band, the gain rare earth ions commonly used for laser generation mainly have Dy 3+、Er3+ and Ho 3+, whose different energy level transition processes correspond to the radiation bands of different wavelengths, respectively, and the radiation bands of these three ions can cover almost the entire 3-4.5 μm wavelength interval, although the radiation band in which rare earth ions are also present is in the 4.5-5 μm band, such as the 7F5→7F6 transition process (corresponding to the radiation wavelength: 4.7 μm) of terbium ions (Tb 3+), but this element has not yet achieved doping in drawn optical fibers. In Er 3+ fluoride doped fibers, the higher energy 4F9/2→4I9/2 transition has a strong radiation band at 3.5 μm. In Ho 3+ fluoride doped fibers 5I5→5I6 is the transition process known to be longest for the output wavelength and the radiation wavelength is 3.9 μm, but only one example of a continuous laser is currently internationally available. In addition, 5S2→5F5 transitions in Ho 3+ fluoride doped fibers can achieve lasing of 3.22 μm. In Dy 3+ -doped fluoride glasses, the radiation band corresponding to the 6H13/2→6H15/2 transition process can be almost covered by 2.5-3.4 μm. For the transition process of 6H11/2→6H13/2 in Dy 3+ -doped fluoride glasses, laser radiation of 4.3 μm can theoretically be achieved, but laser output in optical fibers has not yet been achieved internationally. Therefore, a 3-5 μm mode-locked laser with high peak power and high average power is the most preferred method for direct lasing based on Er 3+ -doped fluoride fiber. As a basis for realizing the laser with the diameter of 3-5 mu m, the laser with the diameter of 3-5 mu m can be obtained by frequency shifting and tuning the laser with the diameter of 3.5 mu m. However, the common dual-wavelength pumping scheme of 1981nm cascade 976nm for generating 3.5 μm laser greatly improves the precision requirement of the whole laser resonant cavity, and stable mode locking pulse can be obtained by adopting NPR (nonlinear polarization rotation) mode locking, but the construction difficulty is extremely high, and only one practical achievement in 21 years internationally exists at present, and the application possibility of the system is limited by an excessively precise system structure. And by adopting material mode locking, firstly, stable mode locking pulse is difficult to obtain, the problem of relaxation of the material is difficult to solve all the time, secondly, the material mode locking is difficult to self-start, the adjusting process is very slow, and the application is difficult. Therefore, achieving high power 3.5 μm mode-locked pulse output remains a major challenge to be addressed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a high-power 3.5 mu m mode locking pulse laser source which can obtain high-power 3.5 mu m mode locking pulse output in application, and meanwhile, the linear cavity structure greatly reduces the structural complexity of a laser, ensures the system stability in high-power output and improves the application possibility of the laser source.
The aim of the invention is mainly realized by the following technical scheme:
A high-power 3.5 mu m mode-locked pulse laser source comprises a super-continuous pumping source, an InF optical fiber, a first lens, a dichroic mirror, an off-axis Er 3+ -doped fluoride optical fiber, a cladding pumping source connected to the dichroic mirror and a second lens connected between the dichroic mirror and the cladding pumping source which are connected in sequence; wherein the super-continuous pumping source is used for generating 1.9-2.3 mu m super-continuous pumping laser; the InF optical fiber is used for expanding the cut-off wavelength of the 1.9-2.3 mu m super-continuous pumping laser to 3.6 mu m, so as to realize the output of the 1.9-3.6 mu m super-continuous pumping laser; the first lens is used for collimating 1.9-3.6 mu m super-continuous pumping laser; the cladding pumping source is used for generating 976nm pumping laser; the second lens is used for collimating 976nm pump laser; the dichroic mirror is used for combining 1.9-3.6 mu m super-continuous pump laser and 976nm pump laser; the off-axis is used for coupling a 1.9-3.6 mu m super-continuous pumping laser fiber core and a 976nm pumping laser cladding; the Er 3+ fluoride doped fiber was used to generate a 3.5 μm mode-locked pulse by stimulated radiation.
In the application, a supercontinuum pump source and a cladding pump source are used as laser output sources to respectively output 1.9-2.3 mu m supercontinuum pump laser and 976nm pump laser, an Er 3+ -doped fluoride optical fiber is used as an output end to output 3.5 mu m mode locking pulse, an InF optical fiber is arranged on an output light path of the 1.9-2.3 mu m supercontinuum pump laser, the cut-off wavelength of the 1.9-2.3 mu m supercontinuum pump laser is expanded to 3.6 mu m and output 1.9-3.6 mu m supercontinuum pump laser, a first lens is arranged on an output light path of the 1.9-3.6 mu m supercontinuum pump laser to collimate the supercontinuum pump laser, a second lens is arranged on an output light path of the 976nm pump laser to collimate the pump laser, a second lens is arranged on an output light path of the 1.9-3.6 mu m supercontinuum pump laser and 976 mu m supercontinuum pump laser to combine the supercontinuum pump laser, an Er pump laser and 976nm pump laser to be arranged between the two-6 mu m supercontinuum pump laser and 3+ and the laser to couple the supercontinuum laser to the laser without chromatic aberration, and the Er pump laser and the laser is coupled to the supercontinuum to the optical fiber between the optical fiber and the optical fiber. When the application is implemented, the super-continuous pumping source carries out power amplification and broadening through the seed source by the multistage amplifier and the nonlinear optical fiber, outputs 1.9-2.3 mu m super-continuous pumping laser, the cut-off wavelength of the output 1.9-2.3 mu m super-continuous pumping laser is extended to 3.6 mu m after passing through the InF optical fiber, thereby outputting 1.9-3.6 mu m super-continuous pumping laser, and outputting the 1.9-3.6 mu m super-continuous pumping laser to the dichroic mirror after being collimated by the first lens, meanwhile, the cladding pumping source outputs 976nm pumping laser, and the 976nm pumping laser is output to the dichroic mirror after being collimated by the second lens, at this time, the 1.9-3.6 mu m super-continuous pumping laser and 976nm pumping laser are combined at the dichroic mirror, and coupled into Er 3+ fluoride optical fiber by focusing without chromatic aberration at the off-axis, wherein the 1.9-3.6 mu m super-continuous pumping laser is coupled as a fiber core at the off-axis, and the 976nm pumping laser is coupled as a cladding at the off-axis.
After 1.9-3.6 mu m super-continuous pumping laser and 976nm pumping laser are coupled into Er 3+ doped fluoride optical fiber, in Er 3+ doped fluoride optical fiber, the ground state Er 3+ ion is pumped by 976nm pumping laser, and transitions from 4I15/2 energy level to 4I11/2 energy level, and then transitions from 4I11/2 energy level to 4F9/2 energy level by absorbing 2 mu m pumping photon in 1.9-3.6 mu m super-continuous pumping laser, when Er 3+ ion transitions from 4F9/2 energy level to 4I9/2 energy level, the Er 3+ ion transitions back from 4I9/2 energy level to 4I11/2 energy level again by emitting 3.5 μm laser, which can be understood as a virtual ground state energy level due to the long lifetime of 4I11/2 energy level, thus forming stable particle circulation between 4I11/2 and 4F9/2 energy levels. Because of the existence of the mode locking pulse of 3.5 mu m in the supercontinuum fiber core pump, the laser generated by stimulated radiation is also the mode locking pulse, thereby stably consuming the energy of 2 mu m wavelength in the supercontinuum pump laser of 1.9-3.6 mu m, amplifying the mode locking pulse of 3.5 mu m wavelength and outputting the mode locking pulse of 3.5 mu m.
Further, the first lens is highly transparent to 1.9-3.6 mu m supercontinuum pumping laser.
Further, the second lens is high in transmission of 976nm pump laser light.
Furthermore, the dichroic mirror has high transmission to 1.9-3.6 mu m super-continuous pumping laser and high reflection to 976nm pumping laser.
Furthermore, the off-axis is highly reflective to both 1.9-3.6 μm supercontinuum pump laser and 976nm pump laser.
Further, a high power 3.5 μm mode-locked pulsed laser source further includes a first AIF 3 end cap connected between the InF fiber and the first lens for preventing damage to the InF fiber output end face in humid air due to moisture absorption of 2.8 μm.
Further, a high power 3.5 μm mode-locked pulsed laser source further includes a second AIF 3 end cap and a third AIF 3 end cap, the second AIF 3 end cap being connected to the off-axis and Er 3+ -doped fluoride fiber, the third AIF 3 end cap being connected to the other end of the Er 3+ -doped fluoride fiber opposite the second AIF 3 end cap, the second AIF 3 end cap and the third AIF 3 end cap both being used to increase the damage threshold of the end face of the Er 3+ -doped fluoride fiber.
Further, a high power 3.5 μm mode-locked pulsed laser source further includes a third lens coupled to the other end of the Er 3+ μm doped fluoride fiber opposite the coupling off-axis, the third lens being highly transparent to the 3.5 μm mode-locked pulses for collimating the 3.5 μm mode-locked pulses.
Further, the high-power 3.5 mu m mode locking pulse laser source further comprises a filter plate, wherein the filter plate is high in transmission of the 3.5 mu m mode locking pulse and is used for filtering residual pump light.
Further, the filter is a 3.5 μm narrow band pass filter.
In summary, compared with the prior art, the invention has the following beneficial effects: according to the invention, the mode locking pulse of 3.5 mu m is amplified by combining the core pumping of the 1.9-3.6 mu m flat supercontinuum laser source with the cladding pumping of 976nm cladding pumping source and the cladding pumping of Er 3+ fluoride optical fiber, so that stable high-power mode locking pulse output of 3.5 mu m is generated after filtering, the structural complexity of the laser is greatly reduced by the linear cavity structure, the system stability during high-power output is ensured, and the application possibility is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
FIG. 1 is a schematic diagram of an embodiment of the present invention;
FIG. 2 is an energy level diagram of Er 3+ ions in an Er 3+ fluoride doped fiber.
The names corresponding to the reference numerals in the drawings are: 1. a supercontinuum pump source; 2. an InF optical fiber; 3. a cladding pump source; 4. a first AIF 3 end cap; 5. a first lens; 6. a second lens; 7. a dichroic mirror; 8. off-axis; 9. a second AIF 3 end cap; 10. an Er 3+ fluoride doped optical fiber; 11. a third AIF 3 end cap; 12. a third lens; 13. a filter; 14. 4F9/2 energy levels; 15. 4I9/2 energy levels; 16. 4I11/2 energy levels; 17. 4I13/2 energy levels; 18. 4I15/2 energy levels; 19. a first upper transition; 20. a second upper transition; 21. a first lower transition; 22. and a second down transition.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
Examples:
As shown in fig. 1, a high power 3.5 μm mode-locked pulsed laser source comprises a supercontinuum pump source 1, an InF optical fiber 2, a first AIF 3 end cap 4, a first lens 5, a dichroic mirror 7, an off-axis 8, a second AIF 3 end cap 9, an Er 3+ doped fluoride optical fiber 10, a third AIF 3 end cap 11, a third lens 12, a filter 13, a cladding pump source 3 connected to the dichroic mirror 7, and a second lens 6 connected between the dichroic mirror 7 and the cladding pump source 3; wherein the super-continuous pumping source 1 is used for generating 1.9-2.3 mu m super-continuous pumping laser; the InF optical fiber 2 is used for expanding the cut-off wavelength of the 1.9-2.3 mu m super-continuous pumping laser to 3.6 mu m to realize the output of the 1.9-3.6 mu m super-continuous pumping laser; the first AIF 3 end cap 4 is used for preventing the output end face of the InF optical fiber 2 from being damaged due to the absorption of 2.8 mu m of water vapor in moist air; the first lens 5 is high in transmittance of 1.9-3.6 mu m super-continuous pumping laser and is used for collimating the 1.9-3.6 mu m super-continuous pumping laser; the cladding pumping source 3 is used for generating 976nm pumping laser; the second lens 6 is high in transmittance of 976nm pump laser and is used for collimating 976nm pump laser; the dichroic mirror 7 has high transmission to 1.9-3.6 mu m super-continuous pumping laser and high reflection to 976nm pumping laser, and is used for combining the 1.9-3.6 mu m super-continuous pumping laser and 976nm pumping laser; the off-axis 8 pairs of 1.9-3.6 mu m supercontinuum pumping laser and 976nm pumping laser are high in reflection and are used for coupling the 1.9-3.6 mu m supercontinuum pumping laser fiber core and the 976nm pumping laser cladding; the second AIF 3 end cap 9 and the third AIF 3 end cap 11 are used for improving the damage threshold of the end face of the Er 3+ -doped fluoride optical fiber 10 so as to improve the upper limit of output power as much as possible; the Er 3+ fluoride doped fiber 10 is used to generate a 3.5 μm mode-locked pulse by stimulated radiation; the third lens 12 is high in transmission of the 3.5 mu m mode locking pulse and is used for collimating the 3.5 mu m mode locking pulse; the filter 13 is highly transparent to the 3.5 μm mode-locked pulses for filtering out residual pump light.
In the implementation of the embodiment, the supercontinuum pump source 1 performs power amplification and broadening through a seed source via a multistage amplifier and a nonlinear optical fiber, outputs 1.9-2.3 μm supercontinuum pump laser, the output 1.9-2.3 μm supercontinuum pump laser is expanded to 3.6 μm after passing through the InF optical fiber 2, thereby outputting 1.9-3.6 μm supercontinuum pump laser, and outputs the supercontinuum pump laser to the dichroic mirror 7 after being collimated by the first lens 5, meanwhile, the cladding pump source 3 outputs 976nm pump laser, the 976nm pump laser is output to the dichroic mirror 7 after being collimated by the second lens 6, at this time, the 1.9-3.6 μm supercontinuum pump laser and the 976nm pump laser are combined at the dichroic mirror 7, and are coupled into the Er-doped 3+ μm fluoride optical fiber 10 through focusing without chromatic aberration of the off-axis 8, and the 3.5 μm mode-locked pulse is output, and the 3.5 μm mode-locked pulse is filtered through the filter 13 after being collimated by the third lens 12, thereby obtaining high-power 3.5 μm mode-locked pulse. Wherein, 1.9-3.6 mu m super-continuous pumping laser is coupled with a fiber core at the off-axis 8, 976nm pumping laser is coupled with a cladding at the off-axis 8, the first AIF 3 end cap 4 is used for preventing the output end face of the InF optical fiber 2 from being damaged by water vapor absorption of 2.8 mu m in moist air, the second AIF 3 end cap 9 and the third AIF 3 end cap 11 are used for improving the damage threshold of the end face of the Er 3+ -doped fluoride optical fiber 10 so as to improve the upper limit of output power as much as possible.
Specifically, in the present embodiment, the cladding pump source 3 is preferably a 976nm laser diode; the off-axis 8 is a reflective focusing mirror, so that focusing without chromatic aberration can be realized, namely, the focal lengths of all wavelengths are consistent; the filter 13 is preferably a 3.5 μm narrow band pass filter.
The energy level diagram of the Er 3+ ion in the Er 3+ -doped fluoride optical fiber 10 is shown in fig. 2, the 4F9/2 energy level 14 is the fifth energy level of the Er 3+ ion in the Er 3+ -doped fluoride optical fiber 10, the 4I9/2 energy level 15 is the fourth energy level of the Er 3+ ion in the Er 3+ -doped fluoride optical fiber 10, the 4I11/2 energy level 16 is the third energy level of the Er 3+ ion in the Er 3+ -doped fluoride optical fiber 10, the 4I13/2 energy level 17 is the second energy level of the Er 3+ ion in the Er 3+ -doped fluoride optical fiber 10, 4I15/2 Energy level 18 is the first energy level of Er 3+ ions in Er 3+ -doped fluoride fiber 10; a first upper transition 19 (GSA: ground State Absorption ground state absorption) occurs between 4I15/2 energy level 18 and 4I11/2 energy level 16, er 3+ ions transitioning from 4I15/2 energy level 18 to 4I11/2 energy level 16; a second upper transition 20 (VGSA: virtual Ground State Absorption virtual ground state absorption) occurs between 4I11/2 energy level 16 and 4F9/2 energy level 14, er 3+ ions transitioning from 4I11/2 energy level 16 to 4F9/2 energy level 14; the first lower transition 21 is an stimulated radiative process, occurring between 4F9/2 energy levels 14 and 4I9/2 energy level 15, er 3+ ions transitioning from 4F9/2 energy level 14 to 4I9/2 energy level 15; a second downward transition 22 (MPR: multi-Phonon Relaxation Multi-phonon relaxation) occurs between 4I9/2 level 15 and 4I11/2 level 16, er 3+ ions transitioning from 4I9/2 level 15 to 4I11/2 level 16.
After 1.9-3.6 μm supercontinuum pump laser and 976nm pump laser are coupled into Er 3+ -doped fluoride fiber 10, in Er 3+ -doped fluoride fiber 10, the ground state Er 3+ ions are pumped by 976nm pump laser, excited from 4I15/2 energy level 18 to 4I11/2 energy level 16 through first upper transition 19, excited from 4I11/2 energy level 16 to higher 4F9/2 energy level 14 through second upper transition 20 by absorbing 2 μm pump photons in 1.9-3.6 μm supercontinuum pump laser, when Er 3+ ions were undergoing the first lower transition 21: 4F9/2→4I9/2 At transition, 3.5 μm laser is emitted, er 3+ ion returns to 4I11/2 level 16 through the second down transition 22, and in combination with the first up transition 19, it can be understood as a virtual ground state level (VGS: virtual Ground State) due to the long lifetime of 4I11/2 level 16, so that stable particle circulation is formed between 4I11/2 and 4F9/2 levels 14. Because of the existence of the mode locking pulse of 3.5 mu m in the supercontinuum fiber core pump, the laser generated by stimulated radiation is also the mode locking pulse, thereby stably consuming the energy of 2 mu m wavelength in the supercontinuum pump laser of 1.9-3.6 mu m, amplifying the mode locking pulse of 3.5 mu m wavelength and outputting the mode locking pulse of 3.5 mu m.
In the embodiment, a mode of 1.9-3.6 mu m flat supercontinuum laser source fiber core pumping and 976nm cladding pumping source 3 cladding pumping Er 3+ doped fluoride optical fiber 10 is adopted to amplify the 3.5 mu m mode locking pulse, compared with the mode locking method in the prior art that continuous laser is generated through a direct laser method, mode locking modulation is carried out and further amplification is carried out, the feasibility of obtaining high-power 3.5 mu m mode locking pulse laser under the current scientific research condition is low, the high-power mode locking pulse laser is difficult to apply, the structural complexity of the laser is greatly reduced through a line cavity structure, the system stability during high-power output is ensured, the application possibility of the high-power mode locking pulse laser is improved, and the application scene of the high-power mode locking pulse laser is widened.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (10)

1. A high power 3.5 μm mode-locked pulsed laser source comprising a supercontinuum pump source (1), an InF fiber (2), a first lens (5), a dichroic mirror (7), an off-axis (8), an Er 3+ -doped fluoride fiber (10), a cladding pump source (3) connected to the dichroic mirror (7), and a second lens (6) connected between the dichroic mirror (7) and the cladding pump source (3) connected in sequence; wherein,
The super-continuous pumping source (1) is used for generating 1.9-2.3 mu m super-continuous pumping laser;
the InF optical fiber (2) is used for expanding the cut-off wavelength of the 1.9-2.3 mu m super-continuous pumping laser to 3.6 mu m to realize the output of the 1.9-3.6 mu m super-continuous pumping laser;
the first lens (5) is used for collimating 1.9-3.6 mu m super-continuous pumping laser;
The cladding pumping source (3) is used for generating 976nm pumping laser;
the second lens (6) is used for collimating 976nm pump laser;
the dichroic mirror (7) is used for combining 1.9-3.6 mu m super-continuous pump laser and 976nm pump laser;
the off-axis (8) is used for coupling a 1.9-3.6 mu m super-continuous pumping laser fiber core and a 976nm pumping laser cladding;
The Er 3+ fluoride doped fiber (10) is used for generating a 3.5 mu m mode locking pulse by stimulated radiation.
2. A high power 3.5 μm mode-locked pulsed laser source according to claim 1, characterized in that the first lens (5) is highly transparent to 1.9-3.6 μm supercontinuum pump laser.
3. A high power 3.5 μm mode-locked pulsed laser source according to claim 1, characterized in that the second lens (6) is highly transparent to 976nm pump laser light.
4. The high power 3.5 μm mode-locked pulsed laser source of claim 1 in which the dichroic mirror (7) is highly transparent to 1.9-3.6 μm supercontinuum pump laser and highly reflective to 976nm pump laser.
5. A high power 3.5 μm mode-locked pulsed laser source as claimed in claim 1, wherein the off-axis (8) is highly reflective to both 1.9-3.6 μm supercontinuum pump laser and 976nm pump laser, and is free of chromatic aberration.
6. The high power 3.5 μm mode-locked pulsed laser source of claim 1, further comprising a first AIF 3 end cap (4), said first AIF 3 end cap (4) being connected between the InF fiber (2) and the first lens (5) for preventing damage to the output end face of the InF fiber (2) in humid air due to absorption of 2.8 μm moisture.
7. The high power 3.5 μm mode-locked pulsed laser source of claim 1 further comprising a second AIF 3 end cap (9) and a third AIF 3 end cap (11), said second AIF 3 end cap (9) being connected to the off-axis (8) and Er 3+ -doped fluoride fiber (10), said third AIF 3 end cap (11) being connected to the other end of the Er 3+ -doped fluoride fiber (10) opposite the second AIF 3 end cap (9), said second AIF 3 end cap (9) and third AIF 3 end cap (11) both being used to raise the damage threshold of the end face of the Er 3+ -doped fluoride fiber (10).
8. The high power 3.5 μm mode-locked pulsed laser source of claim 1 further comprising a third lens (12), said third lens (12) coupled to the other end of the Er 3+ fluoride-doped fiber (10) opposite the coupling-off axis (8), said third lens (12) being highly transparent to the 3.5 μm mode-locked pulses for collimating the 3.5 μm mode-locked pulses.
9. The high power 3.5 μm mode-locked pulsed laser source of claim 8, further comprising a filter (13), the filter (13) being highly transparent to the 3.5 μm mode-locked pulses for filtering out residual pump light.
10. A high power 3.5 μm mode-locked pulsed laser source as claimed in claim 9, wherein said filter (13) is a 3.5 μm narrowband bandpass filter.
CN202410245844.6A 2024-03-05 2024-03-05 High-power 3.5 mu m mode-locked pulse laser source Pending CN118099911A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202410245844.6A CN118099911A (en) 2024-03-05 2024-03-05 High-power 3.5 mu m mode-locked pulse laser source

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202410245844.6A CN118099911A (en) 2024-03-05 2024-03-05 High-power 3.5 mu m mode-locked pulse laser source

Publications (1)

Publication Number Publication Date
CN118099911A true CN118099911A (en) 2024-05-28

Family

ID=91161323

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202410245844.6A Pending CN118099911A (en) 2024-03-05 2024-03-05 High-power 3.5 mu m mode-locked pulse laser source

Country Status (1)

Country Link
CN (1) CN118099911A (en)

Similar Documents

Publication Publication Date Title
EP1564853B1 (en) Fiber amplifier for generating femtosecond pulses in single mode fiber
CN104852260A (en) Dual-wavelength Q-switched pulse fiber laser
CN111064069A (en) All-fiber femtosecond chirped pulse amplification system
CN112600061A (en) Tunable Raman fiber laser
Zong et al. High-power 2.8 μm lasing in a lightly-doped Er: CaF2 crystal
CN105337146B (en) A kind of high peak power pulse mixes thulium laser
CN113964632A (en) High-power single-mode fiber laser
CN113131314A (en) Broadband tunable narrow linewidth single-frequency pulse laser
CN116632637A (en) High-power mid-infrared supercontinuum laser
CN209169626U (en) The gain switch laser of thulium-doped fiber laser pumping
CN217903673U (en) 3-5 micron femtosecond optical fiber amplifier based on red-shift Raman solitons
CN115313130B (en) 2-5 Mu m wide spectrum optical fiber light source based on holmium-doped indium fluoride optical fiber
CN216085690U (en) Simple super-continuum spectrum optical fiber resonant cavity
CN118099911A (en) High-power 3.5 mu m mode-locked pulse laser source
CN115347441A (en) Cascaded pumping 3.5 micron all-fiber femtosecond amplifier based on frequency shift Raman solitons
CN110518445B (en) Broadband tunable optical parameter chirped pulse amplification system based on soliton self-frequency shift
CN110048294B (en) Method for generating high-power intermediate infrared ultrafast pulse laser
CN107482430A (en) A kind of high-power ASE light sources of flat type c band
CN112670812A (en) Intermediate infrared laser based on rare earth ion doped ZBLAN optical fiber
CN117996553B (en) Dual-wavelength femtosecond fiber laser
CN205429410U (en) Thulium laser instrument is mixed in high peak power pulse
US20220085564A1 (en) APPARATUS AND METHOD FOR GENERATING 780 nm ULTRASHORT-PULSED LASER RADIATION
CN103166095A (en) All-fiber pulse laser system with visible waveband
US20220085566A1 (en) 780 nm ULTRASHORT-PULSED FIBER LASER
CN213905814U (en) Tunable Raman fiber laser

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination