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11 pages, 2679 KB

Open AccessArticle

Power-Scaled Mode-Locked Femtosecond Pulses from an All-Polarization-Maintaining Tm-Doped Figure-9 Fiber Laser

by Mingrui Jiang, Ting Wen, Yuhang Wei, Liang Zhao, Senyu Wang, Jinlong Wan, Hongyu Luo and Jianfeng Li

Photonics 2026, 13(3), 245; https://doi.org/10.3390/photonics13030245 - 2 Mar 2026

Viewed by 1049

Abstract

We demonstrate an all-polarization-maintaining (PM) mode-locked thulium-doped fiber laser operating in the net-normal-dispersion regime based on a figure-9 nonlinear amplifying loop mirror (NALM) configuration. A chirped fiber Bragg grating (CFBG) and a commercial PM dispersion-compensating fiber (PM-DCF) are incorporated into the figure-9 cavity, [...] Read more.

We demonstrate an all-polarization-maintaining (PM) mode-locked thulium-doped fiber laser operating in the net-normal-dispersion regime based on a figure-9 nonlinear amplifying loop mirror (NALM) configuration. A chirped fiber Bragg grating (CFBG) and a commercial PM dispersion-compensating fiber (PM-DCF) are incorporated into the figure-9 cavity, providing a large normal net dispersion and enabling stable dissipative-soliton mode-locking. Under stable dissipative-soliton operation, the laser delivers a maximum output power of 53.6 mW at a repetition rate of 12.31 MHz, corresponding to a pulse energy of 4.3 nJ. The output spectrum has a central wavelength of ~1952 nm with a 3 dB bandwidth of ~11 nm. The all-PM laser oscillator directly generates a fs pulse without extra-cavity compression, achieving a pulse duration of 545 fs at the CFBG arm. Moreover, stable fundamental mode-locking is verified by a high radio-frequency signal-to-noise ratio (SNR) exceeding 82 dB and a long-term root-mean-square (RMS) power fluctuation of 0.45% over two hours. To the best of our knowledge, this represents the highest output power generated from an all-PM-fiber figure-9 laser oscillator in the 2 μm band, alongside fs-pulse operation. This high-power, compact, stable and environment-insensitive fs-pulsed laser source shows great potential as an ideal seed for biomedical imaging and mid-infrared frequency combs. Full article

(This article belongs to the Section Lasers, Light Sources and Sensors)

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10 pages, 2577 KB

Open AccessCommunication

Ultrashort Pulses of 32 W and 207 fs at 1 MHz from a Compact All-Fiber Amplifier

by Xin Shao, Xianghao Meng, Tianmeng Jiao, Zhaoqing Gong, Jie Yang, Xianglong Zhao, Guangdao Yang, Yang Bi, Jiahui Chen and Pingxue Li

Photonics 2026, 13(3), 240; https://doi.org/10.3390/photonics13030240 - 28 Feb 2026

Viewed by 564

Abstract

We have demonstrated a high-power, polarization-maintaining all-fiber amplifier operating at a repetition rate of 1 MHz. The seed laser is a Semiconductor Saturable Absorber Mirror (SESAM) mode-locked oscillator with an 18.1 nm full width in half-maximum (FWHM) spectrum. The pulse duration is stretched [...] Read more.

We have demonstrated a high-power, polarization-maintaining all-fiber amplifier operating at a repetition rate of 1 MHz. The seed laser is a Semiconductor Saturable Absorber Mirror (SESAM) mode-locked oscillator with an 18.1 nm full width in half-maximum (FWHM) spectrum. The pulse duration is stretched to 1.1 ns using temperature-controlled chirped fiber Bragg gratings (TCFBGs) and subsequently amplified in a 40 µm core Yb-doped fiber, achieving a maximum output power of 37 W. The amplified laser exhibits excellent beam quality with an M² factor of 1.04. The pulse duration is compressed to 207 fs in a single-grating compressor with 86% efficiency, yielding an average power of 32 W, a pulse energy of 32 µJ, and a peak power of 154.6 MW. This high-power all-fiber femtosecond laser is a promising source for scientific and industrial applications. Full article

(This article belongs to the Special Issue Femtosecond Lasers: Principles, Techniques and Applications)

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9 pages, 1045 KB

Open AccessBrief Report

Kerr-Lens Mode-Locked Tm,Ho:Ca(Gd,Y)AlO₄ Laser

by Zhang-Lang Lin, Peixiong Zhang, Pavel Loiko, Xavier Mateos, Ge Zhang, Zhen Li, Zhenqiang Chen, Uwe Griebner, Weidong Chen and Valentin Petrov

Photonics 2026, 13(1), 38; https://doi.org/10.3390/photonics13010038 - 31 Dec 2025

Viewed by 929

Abstract

We demonstrate Kerr-lens mode-locked operation of a Tm,Ho:Ca(Gd,Y)AlO₄ laser pumped by a narrow-linewidth, continuous-wave Ti:sapphire laser at 797 nm. Soliton pulses as short as 145 fs are generated at 2087.8 nm in σ-polarization via soft-aperture Kerr-lens mode-locking, with an average output power [...] Read more.

We demonstrate Kerr-lens mode-locked operation of a Tm,Ho:Ca(Gd,Y)AlO₄ laser pumped by a narrow-linewidth, continuous-wave Ti:sapphire laser at 797 nm. Soliton pulses as short as 145 fs are generated at 2087.8 nm in σ-polarization via soft-aperture Kerr-lens mode-locking, with an average output power of 203 mW (0.5% output coupler) at ~80.5 MHz. To the best of our knowledge, this result represents the first demonstration of a Kerr-lens mode-locked laser based on a Tm,Ho:Ca(Gd,Y)AlO₄ crystal exhibiting both structural and compositional disorder. Full article

(This article belongs to the Special Issue Emerging Trends in Rare-Earth Doped Material for Photonics)

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24 pages, 4149 KB

Open AccessReview

Research Progress of Passively Mode-Locked Fiber Lasers Based on Saturable Absorbers

by Jiayi Xie, Tengfei Liu, Xilong Liu, Fang Wang and Weiwei Liu

Nanomaterials 2025, 15(23), 1819; https://doi.org/10.3390/nano15231819 - 1 Dec 2025

Cited by 3 | Viewed by 2198

Abstract

Ultrashort fiber lasers are one of the current research hotspots in the field of lasers. They have the advantages of compact structure and high beam quality. Passively mode-locking using saturable absorbers (SAs) is an important scheme for generating picosecond and femtosecond pulses. A [...] Read more.

Ultrashort fiber lasers are one of the current research hotspots in the field of lasers. They have the advantages of compact structure and high beam quality. Passively mode-locking using saturable absorbers (SAs) is an important scheme for generating picosecond and femtosecond pulses. A deep understanding of the passive mode-locking mechanism is key to maturing ultrafast laser technology. In recent years, the passively mode-locking technology of SAs has been improved in material systems, device preparation, and cavity structures. SAs are primarily divided into artificial SAs and real SAs. Real SAs primarily include semiconductor saturable absorption mirrors (SEASAMs) and nanomaterials. Artificial SAs primarily include nonlinear optical loop mirrors (NOLMs), nonlinear multimode interference (NLMMI), nonlinear polarization rotation (NPR), and the Mamyshev oscillator. Herein, we mainly review passively mode-locked fiber lasers employing various SAs, as well as their working principles and technical characteristics. By focusing on the representative achievements, the developmental achievements of ultrafast lasers based on SAs are demonstrated. Finally, the prevailing challenges and promising future research directions in SA’s mode-locking technology are discussed. Full article

(This article belongs to the Special Issue High-Energy Pulsed Laser-Driven Synthesis and Modification of Nanomaterials)

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19 pages, 10165 KB

Open AccessArticle

Experimental Guide for Compact Bow-Tie Femtosecond Solid-State Laser Development

by Vinícius Pereira Pinto, Giovana Trevisan Nogueira, Fátima Maria Mitsue Yasuoka and Jarbas Caiado de Castro Neto

Photonics 2025, 12(6), 548; https://doi.org/10.3390/photonics12060548 - 29 May 2025

Cited by 1 | Viewed by 2361

Abstract

Bow-tie cavity configurations have gained significant attention due to their efficacy in facilitating stable resonator operation for applications requiring short pulse operation and high repetition rate pulses, offering versatility and reliability. While there is an extensive body of literature addressing the theoretical aspects [...] Read more.

Bow-tie cavity configurations have gained significant attention due to their efficacy in facilitating stable resonator operation for applications requiring short pulse operation and high repetition rate pulses, offering versatility and reliability. While there is an extensive body of literature addressing the theoretical aspects and applications of this laser configuration, there exists a gap in practical insights and systematic approaches guidance pertaining to the development and precision alignment of this laser type. The paper achieves this by compiling a range of analytical and optimization techniques for the bow-tie cavity configuration and delineating the necessary steps for the optimization required for continuous wave operation. This ultimately leads to the attainment of the pulsed regime through the Kerr Lens Mode-locking technique, offering a detailed account of the development, optimization, and performance evaluation of a Ti:Sapphire femtosecond laser cavity, using dispersion-compensating mirrors to produce a low-energy pulse of 1 nJ, a high repetition rate of 1 GHz, and a short pulse duration of 61 fs. This work can be useful for researchers and engineers seeking to embark on the development of compact and high-performance femtosecond lasers for a spectrum of applications, encompassing biomedical imaging, laser-assisted surgery, spectroscopy, and optical frequency combs. Full article

(This article belongs to the Section Lasers, Light Sources and Sensors)

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8 pages, 1287 KB

Open AccessCommunication

0.74 W Broadband Degenerate Femtosecond MgO-Doped Periodically Poled Lithium Niobate (MgO: PPLN) Optical Parametric Oscillator at 2056 nm

by Yuxiang Zhao, Bobo Wang, Jinfang Yang, Taotao He, Hao Xu, Xue Qiu, Zhong Dong and Weijun Ling

Photonics 2025, 12(6), 543; https://doi.org/10.3390/photonics12060543 - 27 May 2025

Cited by 1 | Viewed by 1383

Abstract

The degenerate optical parametric oscillator (OPO) is demonstrated to generate high-power, broadband mid-infrared MgO-doped periodically poled lithium niobate (MgO:PPLN) femtosecond laser at 151 MHz, synchronously pumped by a commercial Kerr-lens mode-locked Yb:KGW oscillator at 1028 nm. The average power of the degenerate OPO [...] Read more.

The degenerate optical parametric oscillator (OPO) is demonstrated to generate high-power, broadband mid-infrared MgO-doped periodically poled lithium niobate (MgO:PPLN) femtosecond laser at 151 MHz, synchronously pumped by a commercial Kerr-lens mode-locked Yb:KGW oscillator at 1028 nm. The average power of the degenerate OPO centered at 2056 nm is as high as 740 mW, which is the highest output power from a reported 2 μm degenerate femtosecond OPO, pumped by a bulk solid-state laser. The full width at half maximum (FWHM) spectral bandwidth of the degenerate OPO is 87.4 nm, corresponding to a theoretical, Fourier-limited pulse duration of 51 fs. These remarkable results indicate that degenerate OPO is a great potential candidate technology for generating high-power and few-cycle femtosecond pulses around 2 μm. Such mid-infrared sources are well-suited for high harmonic generation, a pumping source for mid- to far-infrared OPO. Full article

(This article belongs to the Special Issue Advances in Ultrafast Laser Science and Applications)

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8 pages, 1555 KB

Open AccessCommunication

Tunable All-Fiber Femtosecond Electro-Optic Optical Frequency Comb Operating at 1.5 μm

by Aiguo Zhang, Ke Dai, Lin Huang, Liwen Sheng, Zhiming Liu, Yudong Cui, Xiang Hao and Yusheng Zhang

Photonics 2025, 12(4), 311; https://doi.org/10.3390/photonics12040311 - 28 Mar 2025

Cited by 2 | Viewed by 2111

Abstract

We propose and demonstrate a tunable femtosecond electro-optic optical frequency comb by shaping a continuous-wave seed laser in an all-fiber configuration. The seed laser, operating at 1.5 μm, is first cascade-phase-modulated and subsequently de-chirped to generate low-contrast pulses of approximately 8 ps at [...] Read more.

We propose and demonstrate a tunable femtosecond electro-optic optical frequency comb by shaping a continuous-wave seed laser in an all-fiber configuration. The seed laser, operating at 1.5 μm, is first cascade-phase-modulated and subsequently de-chirped to generate low-contrast pulses of approximately 8 ps at a repetition rate of 5.95 GHz. These pulses are then refined into clean, high-quality picosecond pulses using a Mamyshev regenerator. The generated source is further amplified using an erbium–ytterbium-doped fiber amplifier operating in a highly nonlinear regime, yielding output pulses compressed to around 470 fs. Tunable continuously across a 5.7~6 GHz range with a 1 MHz resolution, the picosecond pulses undergo nonlinear propagation in the final amplification stage, leading to output pulses that can be further compressed to a few hundred femtoseconds. By using a tunable bandpass filter, the center wavelength and spectral bandwidth can be flexibly tuned. This system eliminates the need for mode-locked cavities, simplifying conventional ultrafast electro-optic combs by relying solely on phase modulation, while delivering femtosecond pulses at multiple-gigahertz repetition rates. Full article

(This article belongs to the Special Issue Advanced Lasers and Their Applications, 2nd Edition )

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18 pages, 8648 KB

Open AccessArticle

The Study of Soliton Mode-Locked and Bound States in Erbium-Doped Fiber Lasers Based on Cr₂S₃ Saturable Absorbers

by Dong Li, Ruizhan Zhai, Yongjing Wu, Minzhe Liu, Kun Zhao, Qi Yang, Youwei Dong, Xiaoying Li, Xiaoyang Wu and Zhongqing Jia

Materials 2025, 18(4), 864; https://doi.org/10.3390/ma18040864 - 16 Feb 2025

Cited by 2 | Viewed by 2113

Abstract

Femtosecond fiber lasers are widely utilized across various fields and also serve as an ideal platform for studying soliton dynamics. Bound-state solitons, as a significant soliton dynamic phenomenon, attract widespread attention and research interest because of their potential applications in high-speed optical communication, [...] Read more.

Femtosecond fiber lasers are widely utilized across various fields and also serve as an ideal platform for studying soliton dynamics. Bound-state solitons, as a significant soliton dynamic phenomenon, attract widespread attention and research interest because of their potential applications in high-speed optical communication, all-optical information storage, quantum computing, optical switching, and high-resolution spectroscopy. We investigate the effects of pump power variations on the formation of mode-locked solitons and bound-state solitons in a femtosecond fiber laser with a Cr₂S₃ saturable absorber (SA) through numerical simulations while observing the transition, formation, and break-up process of bound soliton pulses. By optimizing the cavity structure and adjusting the net dispersion, the mode-locked soliton is obtained based on this SA. This is the narrowest solitons produced by this SA to date, exhibiting the smallest time-bandwidth product. Moreover, stable double-bound solitons and unique (2 + 1) triple-bound solitons are successfully obtained. The diverse bound-state solitons not only demonstrate the excellent nonlinear absorption properties of Cr₂S₃ as a saturable absorber but also expand the scope of applications for Cr₂S₃ saturable absorbers in fiber lasers. Full article

(This article belongs to the Special Issue Terahertz Materials and Technologies in Materials Science)

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7 pages, 1979 KB

Open AccessCommunication

Excess Intensity Noise in a Nonlinear Amplifying Loop-Mirror-Based Mode-Locked Laser from a Non-Reciprocal Phase Bias

by Dohyeon Kwon

Photonics 2024, 11(12), 1186; https://doi.org/10.3390/photonics11121186 - 18 Dec 2024

Cited by 2 | Viewed by 1672

Abstract

We demonstrate a low-intensity-noise, nonlinear amplifying loop-mirror-based mode-locked fiber laser by optimizing the polarization of the non-reciprocal phase bias and the pump current. If the angle of the waveplate in the non-reciprocal phase bias to the polarization axis of a polarization-maintaining fiber is [...] Read more.

We demonstrate a low-intensity-noise, nonlinear amplifying loop-mirror-based mode-locked fiber laser by optimizing the polarization of the non-reciprocal phase bias and the pump current. If the angle of the waveplate in the non-reciprocal phase bias to the polarization axis of a polarization-maintaining fiber is not carefully aligned, parasitic polarization is induced. The parasitic polarization affects the minimum pump power and dynamic range of pump power for mode-locking, the intensity noise, and the comb power. To reduce intensity noise, the angle of the waveplate for the non-reciprocal phase bias is adjusted, and then the pump power is adjusted. The waveplate angle minimizing the intensity noise maximizes the dynamic range of the pump power for mode-locking and output power. As a result, the relative intensity noise has been suppressed by more than 32 dB at 15 kHz Fourier frequency. The polarization extinction ratio at the non-reciprocal phase bias is critical since it can determine a cavity loss and quality factor of a laser oscillator. Therefore, the additional polarizers cannot improve the intensity noise once the angle is mismatched and the polarization extinction ratio is degraded. Full article

(This article belongs to the Special Issue Advancements in Fiber Lasers and Their Applications)

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33 pages, 16826 KB

Open AccessReview

Recent Advances in Applications of Ultrafast Lasers

by Sibo Niu, Wenwen Wang, Pan Liu, Yiheng Zhang, Xiaoming Zhao, Jibo Li, Maosen Xiao, Yuzhi Wang, Jing Li and Xiaopeng Shao

Photonics 2024, 11(9), 857; https://doi.org/10.3390/photonics11090857 - 11 Sep 2024

Cited by 34 | Viewed by 13348

Abstract

Ultrafast lasers, characterized by femtosecond and picosecond pulse durations, have revolutionized material processing due to their high energy density and minimal thermal diffusion, and have played a transformative role in precision manufacturing. This review first traces the progression from early ruby lasers to [...] Read more.

Ultrafast lasers, characterized by femtosecond and picosecond pulse durations, have revolutionized material processing due to their high energy density and minimal thermal diffusion, and have played a transformative role in precision manufacturing. This review first traces the progression from early ruby lasers to modern titanium–sapphire lasers, highlighting breakthroughs like Kerr-lens mode-locking and chirped pulse amplification. It also examines the interaction mechanisms between ultrafast pulses and various materials, including metals, dielectrics, and semiconductors. Applications of ultrafast lasers in microstructure processing techniques are detailed, such as drilling, cutting, surface ablation, and nano welding, demonstrating the versatility and precision of the technology. Additionally, it covers femtosecond laser direct writing for optical waveguides and the significant advancements in imaging and precision measurement. This review concludes by discussing potential future advancements and industrial applications of ultrafast lasers. Full article

(This article belongs to the Special Issue New Perspectives in Ultrafast Intense Laser Science and Technology)

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14 pages, 2519 KB

Open AccessReview

Developments of Waveguide Lasers by Femtosecond Laser Direct–Writing Technology

by Yang Zhang, Boyan Yu, Zihao Zhang, Xinghao Duan and Junli Wang

Photonics 2024, 11(9), 803; https://doi.org/10.3390/photonics11090803 - 28 Aug 2024

Cited by 15 | Viewed by 7837

Abstract

Waveguide lasers have the advantages of miniature and compact structure and have broad application prospects in photonic integration and on–chip laboratories. The development of femtosecond laser direct–writing technology makes the processing of transparent materials more flexible and controllable. This paper mainly introduces a [...] Read more.

Waveguide lasers have the advantages of miniature and compact structure and have broad application prospects in photonic integration and on–chip laboratories. The development of femtosecond laser direct–writing technology makes the processing of transparent materials more flexible and controllable. This paper mainly introduces a waveguide laser based on femtosecond laser direct–writing technology. Firstly, the applications of femtosecond laser direct–writing technology in an optical waveguide are introduced, including the principles of femtosecond laser direct–writing technology, common optical wave scanning methods, and types of optical waveguides. After that, we summarize the development of a waveguide continuous–wave laser, a Q–switched laser and a mode–locked laser from visible to mid–infrared wavebands and analyze some new representative work. Finally, we explain the difficulty of compensating for dispersion in pulse waveguide lasers and summarize some new ideas that have been proposed to solve the problem. Full article

(This article belongs to the Special Issue New Perspectives in Ultrafast Intense Laser Science and Technology)

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8 pages, 1830 KB

Open AccessArticle

Femtosecond Laser-Written Small-Period Long-Period Fiber Grating for an L-Band Normal Dispersion Mode-Locked Fiber Laser

by Qianying Li, Peiyun Cheng, Rong Zhao and Xuewen Shu

Photonics 2024, 11(8), 693; https://doi.org/10.3390/photonics11080693 - 25 Jul 2024

Cited by 2 | Viewed by 3195

Abstract

We utilize a femtosecond laser-inscribed small-period long-period fiber grating (SP-LPFG) to induce a nonlinear polarization rotation (NPR) effect for mode-locking pulses in a normal dispersion erbium-doped fiber laser (EDFL). The SP-LPFG has a length of 2.5 mm and a period of 25 μm. [...] Read more.

We utilize a femtosecond laser-inscribed small-period long-period fiber grating (SP-LPFG) to induce a nonlinear polarization rotation (NPR) effect for mode-locking pulses in a normal dispersion erbium-doped fiber laser (EDFL). The SP-LPFG has a length of 2.5 mm and a period of 25 μm. At wavelengths of 1556 nm and 1561 nm, it exhibits polarization-dependent loss (PDL) values of 20 dB and 14.5 dB, respectively, sufficient to trigger the NPR mechanism. With the pump power increased to 500 mW, the laser achieves normal dispersion mode-locked pulses centered at 1575 nm in the L-band, with a 3 dB bandwidth of 1.35 nm and a pulse width of 1.61 ps. The radio frequency (RF) spectrum reveals an signal-to-noise ratio (SNR) of up to 63.6 dB, demonstrating the excellent stability of the laser operation. This SP-LPFG holds promising applications, paving the way for efficient, compact, and stable normal dispersion ultrafast fiber lasers. Full article

(This article belongs to the Special Issue Cutting-Edge Developments in Fiber Laser)

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9 pages, 2427 KB

Open AccessCommunication

C- and L-Bands Wavelength-Tunable Mode-Locked Fiber Laser

by Jiajing Lang, Cheng Chen, Pu Zhang, Mei Qi and Haowei Chen

Photonics 2023, 10(12), 1379; https://doi.org/10.3390/photonics10121379 - 14 Dec 2023

Cited by 8 | Viewed by 4794

Abstract

We report a single-wavelength tunable mode-locked fiber laser. The single wavelength can be tuned from 1537.49 nm to 1608.06 nm by introducing a Sagnac loop filter. As far as we know, this is the widest single-wavelength tuning range achieved in an erbium-doped mode-locked [...] Read more.

We report a single-wavelength tunable mode-locked fiber laser. The single wavelength can be tuned from 1537.49 nm to 1608.06 nm by introducing a Sagnac loop filter. As far as we know, this is the widest single-wavelength tuning range achieved in an erbium-doped mode-locked all-fiber laser based on nonlinear amplifying loop mirror (NALM). The laser’s pulse width changes from 549 fs to 808 fs throughout the tuning process, the maximum average output power is 5.72 mW, and the single-pulse energy is 0.34 nJ at a central wavelength of 1556.53 nm. This laser source can serve as an efficient tool for applications that require a broad tunability range. The combination of femtosecond pulses and extensive wavelength tuning capabilities makes this laser system highly valuable in fields such as fiber optic communications, spectroscopy, sensing, and other applications that benefit from ultrafast and tunable laser sources. Full article

(This article belongs to the Special Issue New Advances in Ultrashort Pulse Fiber Lasers and Their Applications)

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10 pages, 2252 KB

Open AccessArticle

Continuous-Wave and Mode-Locked Operation of an In-Band Pumped Tm,Ho,Lu:CaGdAlO₄ Laser

by Huangjun Zeng, Wenze Xue, Robert T. Murray, Weidong Chen, Zhongben Pan, Li Wang, Chen Cui, Pavel Loiko, Xavier Mateos, Uwe Griebner and Valentin Petrov

Appl. Sci. 2023, 13(23), 12927; https://doi.org/10.3390/app132312927 - 3 Dec 2023

Cited by 5 | Viewed by 2580

Abstract

We investigate in-band pumping of a Tm,Ho,Lu:CaGdAlO₄ laser using a Raman-shifted Er-fiber laser (1678 nm), in the continuous-wave (CW) and mode-locked (ML) regimes. A maximum output power of 524 mW is obtained in the CW regime with a 5% output coupler at [...] Read more.

We investigate in-band pumping of a Tm,Ho,Lu:CaGdAlO₄ laser using a Raman-shifted Er-fiber laser (1678 nm), in the continuous-wave (CW) and mode-locked (ML) regimes. A maximum output power of 524 mW is obtained in the CW regime with a 5% output coupler at an absorbed pump power of 2.04 W, corresponding to a slope efficiency of 27.9%. A maximum CW wavelength tuning range of 160 nm at the zero level, from 1984 to 2144 nm, is obtained with a 0.2% output coupler. In the ML regime, pumping with 5.5 W (unpolarized), the average output power (0.2% output coupler) reaches 148 mW at a repetition rate of ~96 MHz. The output spectrum is centered at 2071.5 nm with a FWHM of 21.5 nm (σ-polarization). The pulse duration amounts to 218 fs (time-bandwidth product equal to 0.327). Full article

(This article belongs to the Section Optics and Lasers)

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11 pages, 3042 KB

Open AccessArticle

Transform-Limited Sub-100-fs Cr:ZnS Laser with a Graphene-ZnSe Saturable Absorber

by Won Bae Cho and Dong Ho Shin

Photonics 2023, 10(10), 1108; https://doi.org/10.3390/photonics10101108 - 30 Sep 2023

Cited by 2 | Viewed by 2295

Abstract

In this work, we present ultrashort pulse generation from passively mode-locked Cr:ZnS laser with a monolayer graphene-coated ZnSe substrate exhibiting high nonlinearity. The femtosecond Cr:ZnS laser produces output power up to 330 mW at a 233 MHz repetition rate. Even in the presence [...] Read more.

In this work, we present ultrashort pulse generation from passively mode-locked Cr:ZnS laser with a monolayer graphene-coated ZnSe substrate exhibiting high nonlinearity. The femtosecond Cr:ZnS laser produces output power up to 330 mW at a 233 MHz repetition rate. Even in the presence of an uneven negative dispersion profile, the enhanced self-phase modulation by the ZnSe substrate of the graphene saturable absorber enables the polycrystalline Cr:ZnS laser to produce slightly chirped 99 fs pulses at 2373 nm. With extracavity dispersion compensation using a mixture of 3 mm and 2 mm thick ZnSe plates, the pulse width was compressed from 99 fs to 73 fs, resulting in an improved time–bandwidth product from 0.431 to 0.318. Assuming a sech² pulse shape (0.315), the pulses were almost transform-limited. These results indicate that utilizing a graphene saturable absorber on a substrate with high nonlinearity presents an effective method for developing sub-100 fs solid-state lasers within the mid-IR spectral range. Full article

(This article belongs to the Section Lasers, Light Sources and Sensors)

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