A high peak power all-fiber femtosecond laser system based on GMN spectral shaping technique
By introducing spectral shaping anti-gain narrowing technology into the femtosecond laser system and combining it with an all-fiber structure, the problems of low peak power and nonlinear effects in existing femtosecond lasers have been solved, realizing high-energy, high-peak-power femtosecond laser output and expanding the application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING UNIV OF TECH
- Filing Date
- 2024-11-14
- Publication Date
- 2026-06-05
AI Technical Summary
Existing femtosecond lasers have low peak power, making it difficult to meet diverse application requirements. Furthermore, they are limited by nonlinear effects such as self-phase modulation and stimulated Raman scattering during amplification, resulting in reduced pulse quality. Additionally, the peak power of GMN light sources is limited.
A high peak power femtosecond laser system based on gain management nonlinear amplification and anti-gain narrowing technology is adopted. The spectrum is modulated by spectral shaping technology. Based on the GMN spectrum, the intensity difference at the highest point of the relative signal spectrum at the gain peak is greater than 20dB. Combined with the all-fiber structure, ultra-short pulse width and high peak power output are achieved.
It has achieved high peak power femtosecond laser output below 100 femtoseconds, overcomes the limitations of nonlinear effects, broadens the application range, and improves the output energy and peak power of laser systems.
Smart Images
Figure CN119481906B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of laser technology and nonlinear optics, and particularly relates to a high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology. Background Technology
[0002] Femtosecond lasers, with their ultrashort pulse widths and ultra-high peak power, have demonstrated significant application value in various fields such as precision manufacturing, biomedicine, and defense aerospace. In particular, femtosecond fiber lasers, with their compact system design, excellent beam quality, and reliable environmental adaptability, have driven tremendous progress in these fields.
[0003] Currently, fiber lasers primarily rely on mode-locking technology to generate ultrashort pulse lasers. However, the lasers directly output by this technology often have relatively low peak power, making it difficult to meet diverse application requirements. To address this issue, power amplification is typically required using a laser amplifier. However, direct laser amplification in an amplifier is constrained by nonlinear effects such as self-phase modulation (SPM) and stimulated Raman scattering (SRS), which limit the increase in pulse peak power and may lead to a decrease in pulse quality. To overcome the limitations of nonlinear effects, chirped pulse amplification (CPA) technology has become a common method for increasing pulse peak power. This technology effectively reduces the influence of nonlinear effects by stretching the pulse before amplification, ultimately achieving high peak power and narrow pulse width laser output. However, due to dispersion mismatch and the effect of gain narrowing, the compressed pulse width often falls below 200 femtoseconds, limiting its application range.
[0004] In recent years, with the development of laser technology, a gain-managed nonlinear (GMN) amplification technique has been proposed. This technique can overcome the limitation of gain narrowing by utilizing the nonlinear effect in the amplification process, greatly broaden the spectral width, and achieve laser output with a pulse width of less than 100 femtoseconds. However, due to the nonlinear characteristics of optical fibers and the limitation of damage threshold, it is difficult to achieve higher peak power output.
[0005] To overcome these challenges, this invention proposes an innovative femtosecond laser system. This system further amplifies the broadband light source generated by GMN technology while introducing spectral shaping anti-gain narrowing technology. It aims to achieve femtosecond laser output with sub-hundred femtosecond, high energy, and high peak power, which has broad application prospects in the fields of high-precision processing and nonlinear optics research. Summary of the Invention
[0006] To address the low peak power issue of existing GMN (Glass Media Narrowing) light sources, this invention proposes a high peak power femtosecond laser system that further amplifies a GMN broadband light source while incorporating anti-gain narrowing technology. In this system, anti-gain narrowing is achieved through spectral shaping. The output of the mode-locked seed source is pre-compressed by a bandpass filter before being injected into the GMN amplifier for amplification. The amplified laser then enters the spectral shaping system and subsequently the main laser amplifier. Ultimately, this method enables the output of a high peak power femtosecond laser with a pulse width of less than 100 femtoseconds. Compared to direct output from a GMN amplification system, this method achieves ultrashort pulse output while further increasing the peak power of the laser.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A high peak power femtosecond laser system based on gain-managed nonlinear amplification and anti-gain narrowing technology is characterized by comprising an all-fiber GMN seed source, an all-fiber anti-gain narrowing spectral shaping system based on a nonlinear amplifying ring mirror, a high-power fiber laser amplifier, and a pulse compressor.
[0009] The all-fiber GMN seed source includes: a first all-fiber linear cavity CFBG mode-locked laser, a first bandpass filter, a first pump source, a first beam combiner, a first gain fiber, and a first pump beam stripper. The output of the first all-fiber linear cavity CFBG mode-locked laser is connected to the input of the first bandpass filter, and the output of the first bandpass filter is connected to the signal end of the first beam combiner. The pump end of the first beam combiner is connected to the output of the first pump source. The output of the first beam combiner is sequentially connected to the first gain fiber and the first pump beam stripper, and the output of the first pump beam stripper is connected to a spectral shaping system.
[0010] The all-fiber anti-gain narrowing spectral shaping system includes: a first circulator, a first 2x2 beam splitter, a second pump source, a first wavelength division multiplexer (WDM), a second gain fiber, a first passive fiber, and a third gain fiber. The output of the all-fiber GMN seed source is connected to end 1 of the first circulator. End 2 of the first circulator is connected to the first 2x2 beam splitter. The output port of the first 2x2 beam splitter is connected to the first WDM signal end. The pump section of the first WDM is connected to the second pump source. The output of the first WDM is sequentially connected to the second gain fiber and the first passive fiber. The output of the first passive fiber returns to port 2 of the first circulator via the 2x2 beam splitter and is then output via port 3. The output of port 3 of the first circulator is connected to the third gain fiber. The output of the third gain fiber is connected to the high-power laser main amplifier.
[0011] The high-power fiber laser amplifier and pulse compressor include: a second beam combiner, a third pump source, a fourth gain fiber, a second pump stripper, and a first grating pair compressor. The output of the anti-gain narrowing spectral shaping system is connected to the signal end of the second beam combiner. The third pump source is connected to the pump end of the second beam combiner. The output of the beam combiner is then connected to the fourth gain fiber. The output of the third gain fiber is connected to the second pump stripper. The output of the second pump stripper is connected to the first grating pair compressor.
[0012] As a preferred embodiment, the first all-fiber linear cavity CFBG mode-locked laser has an output center wavelength of 1000-1050nm, a spectral bandwidth of 1-25nm, a pulse width of 0.1-20ps, a repetition frequency of 0.1-100MHz, and a pulse energy of 0.1-10nJ. After pre-compression by a bandpass filter, the pulse width is less than 2ps.
[0013] Preferably, the pump source is a semiconductor laser, the laser type is a continuous laser, and the output fiber is a single-mode fiber or a multimode fiber.
[0014] Preferably, the gain fiber is a quartz fiber doped with ytterbium (Yb) rare earth ions, and the fiber type can be single-clad fiber or double-clad fiber, with a fiber core diameter between 4-50 μm.
[0015] Preferably, the optical fiber device and the optical fiber are coupled by optical fiber fusion splicing.
[0016] Compared with the prior art, the advantages of the present invention are:
[0017] This invention provides a high peak power femtosecond laser based on gain-managed nonlinear amplification technology and anti-gain narrowing technology. By modulating the spectrum using spectral shaping technology, a concave shaping effect with an intensity difference of more than 20 dB between the gain peak and the highest point of the signal spectrum is achieved on the basis of the GMN spectrum. This suppresses gain narrowing during amplification, and finally, after laser compression, a sub-100 femtosecond output is successfully achieved. Simultaneously, the peak power relative to the GMN amplifier is further improved. This invention has a significant effect on improving the peak power of GMN amplifiers, which is beneficial for expanding the application range of GMN lasers. Attached image description:
[0018] Figure 1 This is a schematic diagram of a femtosecond laser system based on gain management nonlinear amplification and anti-gain narrowing technology, provided for the implementation of this invention.
[0019] Figure 2 This is a logic diagram of the laser system of the present invention.
[0020] Among them, 1. an all-fiber ultrashort pulse mode-locked laser, 2. a first bandpass filter, 3. a first pump source, 4. a first beam combiner, 5. a first gain fiber, 6. a first pump stripper, 7. a first circulator, 8. a first 2x2 beam splitter, 9. a second pump source, 10. a first wavelength division multiplexer, 11. a second gain fiber, 12. a first passive fiber, 13. a third passive fiber, 14. a third pump source, 15. a second beam combiner, 16. a fourth gain fiber, 17. a second pump stripper, and 18. a first grating pair compressor. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to several accompanying drawings and embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. The specific embodiments described herein are only for explaining the invention and do not limit the invention.
[0022] This invention discloses a high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology, comprising: an all-fiber broadband GMN seed source, an all-fiber anti-gain narrowing spectral shaping system based on a nonlinear amplifying ring mirror, a high-power fiber laser amplifier, and a pulse compressor; it includes the following optical components: a pump source, a wavelength division multiplexer, a gain fiber, a 2×2 fiber coupler, a beam combiner, a filter, a pump stripper, and a grating pair compressor. This invention's high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology, while further amplifying the broadband light source generated by GMN technology, introduces spectral shaping anti-gain narrowing technology, thereby improving the output energy and peak power of the laser system while ensuring ultrashort pulse width femtosecond laser output, and broadening the application prospects of gain-managed nonlinear amplification technology.
[0023] like Figure 1 As shown, an all-fiber one-second laser system based on gain-managed nonlinear amplification technology and anti-gain narrowing technology includes: 1. an all-fiber ultrashort pulse mode-locked laser, 2. a first bandpass filter, 3. a first pump source, 4. a first beam combiner, 5. a first gain fiber, 6. a first pump stripper, 7. a first circulator, 8. a first 2x2 beam splitter, 9. a second pump source, 10. a first wavelength division multiplexer, 11. a second gain fiber, 12. a first passive fiber, 13. a third passive fiber, 14. a third pump source, 15. a second beam combiner, 16. a fourth gain fiber, 17. a second pump stripper, and 18. a first grating pair compressor.
[0024] like Figure 2 As shown in the above laser system logic flowchart, the following steps are included:
[0025] The ultrashort pulses generated by the all-fiber mode-locked laser 1 are input to a bandpass filter for compression. This compression, achieved through filtering, ensures the pulse width of the laser output from the pre-compressor 2 is within 2 picoseconds. The pulses then enter GMN amplifiers 3-6, where nonlinear effects and gain management are used to broaden the spectrum, allowing for pulse output with a compressed pulse width of tens of femtoseconds. The pulses output from the fiber GMN amplifiers 3-6 are then input to a spectral shaping system 7-13. The GMN output is a broadband light source, with different wavelengths corresponding to different intensities. This spectral shaping system responds differently to different laser intensities, thus modulating the spectrum and achieving spectral shaping. Simultaneously, the system utilizes the difference in absorption coefficients of the gain fiber for different wavelengths to achieve a spectral concavity shaping effect exceeding 20dB. Finally, the shaped laser enters the main laser amplifier and compressors 14-18. Entering the main amplifier further increases the pulse energy, and due to the anti-gain narrowing effect of the front-end spectral shaping, a wide spectral width is maintained. After entering compressor 18, a high peak power laser output with a pulse width below 100 femtoseconds is achieved.
[0026] This invention provides a compact, stable femtosecond laser capable of achieving ultrashort pulse widths and high peak power. Based on gain-managed nonlinear amplification and anti-gain narrowing techniques, compared to a pure GMN laser, the combination of anti-gain narrowing technology increases the system's output pulse energy while maintaining a narrow pulse width, further expanding the application range of GMN lasers.
Claims
1. A high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology, characterized in that, This includes an all-fiber broadband GMN seed source, an all-fiber anti-gain narrowing spectral shaping system based on a nonlinear amplifying ring mirror NALM, a high-power fiber laser amplifier, and a pulse compressor. The all-fiber broadband GMN seed source includes: a first all-fiber linear cavity CFBG mode-locked laser, a first bandpass filter, a first pump source, a first beam combiner, a first gain fiber, and a first pump beam stripper; the output end of the first all-fiber linear cavity CFBG mode-locked laser is connected to the input end of the first bandpass filter, the output end of the first bandpass filter is connected to the signal end of the first beam combiner, wherein the pump end of the first beam combiner is connected to the output end of the first pump source; the output end of the first beam combiner is sequentially connected to the first gain fiber and the first pump beam stripper, and the output end of the first pump beam stripper is connected to the all-fiber anti-gain narrowing spectral shaping system; The all-fiber anti-gain narrowing spectral shaping system includes: a first circulator, a first 2×2 beam splitter, a second pump source, a first wavelength division multiplexer, a second gain fiber, a first passive fiber, and a third gain fiber; the output end of the all-fiber GMN seed source is connected to end 1 of the first circulator, end 2 of the first circulator is connected to the first 2×2 beam splitter, the output port of the first 2×2 beam splitter is connected to the first wavelength division multiplexer signal end, the pump section of the first wavelength division multiplexer is connected to the second pump source, the output end of the first wavelength division multiplexer is sequentially connected to the second gain fiber and the first passive fiber, the output end of the first passive fiber returns to port 2 of the first circulator via the 2×2 beam splitter and is output via port 3, the output end of port 3 of the first circulator is connected to the third gain fiber, and the output end of the third gain fiber is connected to the high-power laser main amplifier; The high-power fiber laser amplifier and pulse compressor include: a second beam combiner, a third pump source, a fourth gain fiber, a second pump stripper, and a first grating pair compressor; the output of the anti-gain narrowing spectral shaping system is connected to the signal end of the second beam combiner, the third pump source is connected to the pump end of the second beam combiner, the output of the beam combiner is then connected to the fourth gain fiber, the output of the third gain fiber is connected to the second pump stripper, and the output of the second pump stripper is connected to the first grating pair compressor.
2. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, The first all-fiber linear cavity CFBG mode-locked laser has a center wavelength of 1000-1050nm, a full width at half maximum (FWHM) of 1-20nm, a pulse width of 0.1-20ps, a repetition frequency of 1-100MHz, and a pulse energy of 0.1-10nJ. After pre-compression by a bandpass filter, the pulse width is less than 2ps.
3. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, The first bandpass filter has a center wavelength of 1000-1040nm and a bandwidth of 1-3nm.
4. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, The pump source is a semiconductor laser, the laser type is a continuous laser, and the output fiber is a single-mode fiber or a multimode fiber.
5. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, Optical fiber devices and optical fibers are coupled together by optical fiber fusion splicing.
6. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, In the nonlinear magnifying ring mirror NALM-based anti-gain narrowing spectral shaping system, the first 2×2 beam splitter has a beam splitting ratio between 0 and 1.
7. The high peak power all-fiber femtosecond laser system based on GMN spectral shaping technology as described in claim 1, characterized in that, The gain fiber is a quartz fiber doped with ytterbium rare earth ions. The fiber type is single-clad fiber or double-clad fiber, and the fiber core diameter is between 4-50 μm.