In this paper, we report 4 different saturable absorbers based on 4 transition metal dichalcogenides (MoS2, MoSe2, WS2, WSe2) and utilize them to Q-switch a ring-cavity fiber laser with identical cavity configuration. It is found that MoSe2 exhibits highest modulation depth with similar preparation process among four saturable absorbers. Q-switching operation performance is compared from the aspects of RF spectrum, optical spectrum, repetition rate and pulse duration. WS2 Q-switched fiber laser generates the most stable pulse trains compared to other 3 fiber lasers. These results demonstrate the feasibility of TMDs to Q-switch fiber laser effectively and provide a meaningful reference for further research in nonlinear fiber optics with these TMDs materials.

Q-switched fiber laser based on transition metal dichalcogenides MoS 2 , MoSe 2 , WS 2 , and WSe 2

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation, photonic crystal fiber

Infrared (2–12 μm) solid-state laser sources: a review

We experimentally demonstrate mid-infrared (MIR) supercontinuum (SC) generation spanning ∼2.0 to 15.1 μm in a 3 cm-long chalcogenide step-index fiber. The pump source is generated by the difference frequency generation with a pulse width of ∼170  fs, a repetition rate of ∼1000  Hz, and a wavelength range tunable from 2.4 to 11 μm. To the best of our knowledge, this is the broadest MIR SC generation observed so far in optical fibers. It facilitates fiber-based applications in sensing, medical, and biological imaging areas.

Mid-infrared supercontinuum generation spanning 2.0 to 15.1 μm in a chalcogenide step-index fiber.

The 2.94 μm Er:YAG laser Q-switched mechanically by a rotating mirror was developed. The laser generated pulses of 30 mJ energy and duration below 290 ns, which corresponds to over 100 kW peak power. It operated at the repetition rate of up to 25 Hz. To our knowledge it is the most powerful erbium laser operating at so high repetition rate. The developed laser can be successfully applied in medicine – e.g. in microsurgery of soft biological tissues.

https://iopscience.iop.org/article/10.1002/lapl.201010019/pdf

Mid-infrared Q-switched Er:YAG laser for medical applications

An actively Q-switched Er:YAG laser generating pulses at 2.94 μm has been developed and investigated. For a single Er:YAG generator at 3 Hz repetition rate, pulses of 91.2 ns duration and 137 mJ energy have been obtained. It corresponds to pulse train with high-peak power of ~ 1.5 MW. For 10 Hz repetition rate 30 mJ of output energy in single pulse has been achieved. These results, according to our knowledge, are the best world-wide achievements.

Electrooptically Q-switched mid-infrared Er:YAG laser for medical applications

High-power mid-infrared supercontinuum sources: Current status and future perspectives

We demonstrate a novel method of mid-infrared (mid-IR) supercontinuum (SC) generation with the use of a 2 µm gain-switched self-mode-locked thulium-doped fiber laser. SC radiation ranging from ~1.9 to 3.8 µm wavelength, generated in a single-mode ZBLAN fiber with a zero-dispersion wavelength (ZDW) shifted to ~1.9 µm, is reported. An average output power of 0.74 W with 0.27 W at wavelengths longer than 2.4 µm was measured. It is, to the best of our knowledge, the first report on such an approach to generate a mid-IR SC in optical fibers.

Mid-IR supercontinuum generation in a ZBLAN fiber pumped by a gain-switched mode-locked Tm-doped fiber laser and amplifier system

Mid-infrared supercontinuum (SC) generation in a thulium fiber amplifier is reported. The system delivered an average output power of 2.37 W in a spectral band of ?(1.75?2.7)??m which is, to the best of our knowledge, the highest average power of SC generated from a single-mode Tm-doped fiber. For wavelengths longer than 2.4??m, the output power was as high as 0.49?W, constituting almost 21% of the total output power. A 10 dB spectral flatness in the wavelength interval ranging from 1.95 to 2.52??m (570?nm span) with a corresponding (calculated) spectral power density greater than 3?mW?nm?1 is demonstrated. Amplification in both emission bands of Tm3+ ions, as a way to effectively enhance SC generation towards longer wavelengths, is also discussed.

https://iopscience.iop.org/article/10.1088/1612-2011/10/3/035105/pdf

Jacek Swiderski

Papers

Mid-infrared Q-switched Er:YAG laser for medical applications

Electrooptically Q-switched mid-infrared Er:YAG laser for medical applications

High-power mid-infrared supercontinuum sources: Current status and future perspectives

Mid-IR supercontinuum generation in a ZBLAN fiber pumped by a gain-switched mode-locked Tm-doped fiber laser and amplifier system

Mid-infrared supercontinuum generation in a single-mode thulium-doped fiber amplifier