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Stimulated Raman Scattering (SRS), pumped by a broadband (i.e., compared to the bandwidth of the material excitation) chirped 50-ps pulse, with Stokes seeding by a 20-ns narrowband pulse, is experimentally and theoretically investigated. In the experiments, a femtosecond-class 0.95 μm Ti:sapphire laser system and a Q-switched 1.064 μm Nd:YAG laser were used for pumping and seeding SRS in a calcite (CaCO3) crystal. This material was chosen because its Raman resonance frequency (∼1089 cm−1) is near to the frequency difference between the pump and seed radiation. It is shown that, despite a narrowband seed, the generated Stokes pulse spectrum mimics the pump pulse spectral width. The observed SRS conversion efficiency saturates at 40%, with a weak dependence on the seed pulse energy and on the detuning of the pump-seed frequency from the Raman resonance. Theoretical modeling confirms the observed effects and permits prediction of the characteristics of the investigated system as its parameters are varied. [ABSTRACT FROM AUTHOR]

Pulsed polarized vortex beams, a special form of structured light, are generated by tailoring the light beam spatiotemporally and witness the growing application demands in nonlinear optics such as ultrafast laser processing and surface plasma excitation. However, existing techniques for generating polarized vortex beams suffer from either low compactness due to the use of bulky components or limited controlment of pulse performance. Here, an all-fiber technique combining plasmonic metafibers with mode conversion method is harnessed to generate high-performance pulsed polarized vortex beams. Plasmonic metafibers are utilized as saturable absorbers to produce Q-switched pulses with micro-second duration, while the offset splicing method is employed to partially convert the fundamental transverse mode (LP 01 ) to higher-order mode (LP 11 ). Eventually, a polarized vortex beams laser is achieved at the telecom band with a repetition frequency of 116.0 kHz. The impact of geometrical parameters including period of metafibers and offset of splicing on the spatiotemporal properties of pulsed polarized vortex beams is systematically investigated. Our findings could pave the way for design, control and generation of all-fiber pulsed polarized vortex beams, and also offer insights into the development of other types of structured laser sources. [ABSTRACT FROM AUTHOR]

We report passively Q-switched pulse operation through an erbium-doped fiber laser (EDFL) utilizing graphene oxide/titania (GO/TiO2) nanorods as a saturable absorber. The GO/TiO2 nanorods were fabricated using a Sol–gel-assisted hydrothermal method. The optical and physical characterization of the GO/TiO2 was then characterized using a field-emission-scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and diffuses reflectance spectroscopy (DRS). To investigate the performance of the Q-switched EDFL based on the GO/TiO2 SA, the prepared nanorods were mechanically deposited on the fiber ferrule employing adhesion effects of in-dex-matching gel. This integration of the nanorod SA resulted in a self-starting Q-switching opera-tion initiated at a pump power of 17.5 mW and sustained up to 306.9 mW. When the pump range was tuned from 17.5 to 306.9 mW, the emission wavelength varied from 1564.2 to 1562.9 nm, pulse repetition rates increased from 13.87 kHz to 83.33 kHz, and pulse width decreased from 30.27 µs to 3.75 µs. Moreover, at the maximum pump power of 306.9 mW, the laser exhibited an average output power of 0.74 mW, a peak power of 1.54 mW, and a pulse energy of 8.88 nJ. Furthermore, this study investigates the GO/TiO2 damage threshold and prolonged stability of the proposed EDFL system. [ABSTRACT FROM AUTHOR]

In this paper, a Wide tunble in C + L band single-wavelength passively Q-switched fiber laser (PQFL) consisting of cascaded doped fiber segments and a tunable band-pass filter (TBF) is proposed. The TBF achieves precise tuning of the wavelength with a maximum tunable range of 45.04 nm (1529.08–1574.12 nm). When the fiber is non-completely pumped, erbium-doped fiber (EDF) and erbium-ytterbium co-doped fiber (EYDF) act as saturable absorbers (SA). It has different nonlinearities under different pump power combinations, producing passively Q-switched pulses with repetition frequencies from 8.23 kHz to 46.47 kHz and pulse widths reduced from 12.82 μs to 2.00 μs. In addition, the wavelength range of passively Q-switched is also changing from 11.55 nm to 31.04 nm. In the experiment, the change in the wavelength range of the passively Q-switched pulse was explained by analyzing the gain saturation absorption characteristics of the EDF and the EYDF. In the experiment, only four devices are used to achieve single-wavelength wide tuning and passively Q-switched, which is enough to prove the simplicity and compactness of the structure. The proposed FQFL has broad application prospects in the fields of distributed sensing systems and bio-medical imaging. [ABSTRACT FROM AUTHOR]

The ultra-high-frequency pulse trains in a Yb:LuAG passively Q-switched laser with a Yb ratio of 15 at. % are experimentally investigated. The pulse trains consist of a low-frequency harmonic spectrum pulse train with a fundamental frequency below 500 KHz as the source and an ultra-high-frequency harmonic spectrum pulse train with an exciting fundamental frequency above 104 KHz. The basic frequency of the low spectrum increases approximately linearly with increasing pump power. The change law of the fundamental frequency of the ultra-high frequency spectrum with the increase in pump power conforms to the frequency-doubling principle of the harmonic spectrum changing to a higher frequency, and increases exponentially with A × 2n (n is a natural number, A = 1.25 × 108, 1.552 × 108, or 1.0 × 108 Hz). In this paper, the base frequency range of the ultra-high-frequency spectrum was 0.077 73 GHz–0.66 THz. The maximum average peak power of an ultra-high-frequency pulse was 18.25 mW, and the minimum width of an ultra-high-frequency pulse was 3.2 ps. [ABSTRACT FROM AUTHOR]

WSe2 and CuO belong to transition metal chalcogenides (TMDs) and transition metal oxides (TMOs), respectively, and both are semiconductor materials that have been applied in production in many fields. In this work, WSe2/CuO heterojunction nanocomposites were prepared by simple and non-toxic liquid phase exfoliation (LPE) and vacuum filtration methods, and WSe2/CuO heterojunction saturable absorber (SA) devices were prepared by film transfer technology. The morphology and purity of the WSe2/CuO heterojunction were studied. In addition, the WSe2/CuO heterojunction SA was applied to a passively Q-switched (PQS) solid-state laser for the first time, generating a stable pulse output with a Watt-level output power, a maximum average output power of 2.32 W, a repetition frequency of 68.68 kHz, and a minimum pulse width of 752.8 ns. Our research results illustrate the great potential and broad application prospects of WSe2/CuO composites in the field of photonic devices. [ABSTRACT FROM AUTHOR]

Pulsed solid‐state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q‐switched and mode‐locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid‐state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid‐state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid‐state lasers with 2D materials‐based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid‐state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas. [ABSTRACT FROM AUTHOR]

The synthesis of 2D MoWS2 nanosheets involved the liquid-phase exfoliation technique was explored in this paper. The nonlinear optical response of MoWS2 was characterized in the 1 µm wavelength range, and its suitability as a saturable absorber (SA) was confirmed. Experimental demonstrations were conducted by using MoWS2 as an SA in an idler-resonant intracavity KTA optical parametric oscillator (OPO) driven by a dual-loss-modulated Q-switched and mode-locked (QML) YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM). By appropriately tuning the pump power and the AOM repetition rate, the Q-switched envelope pulse widths for the signal and idler waves could be significantly reduced to be shorter than the cavity round-trip transit time, i.e., the interval between two neighboring mode-locking pulses. Consequently, this enabled the generation of sub-nanosecond single mode-locking pulses with a low repetition rate, high pulse energy, and remarkable stability. With a repetition rate of 1 kHz and maximal pulse energies of 318 µJ and 169 µJ, respectively, sub-nanosecond single mode-locking pulses of the signal and idler waves were generated. The theoretical model was established using coupled rate equations with a Gaussian spatial distribution approximation. The numerical simulation results for generating sub-nanosecond single mode-locking pulses for the signal and idler waves within their respective Q-switched envelopes aligned fundamentally with the experimental results, proving that MoWS2 can be a potential nanomaterial for further optoelectronic applications. [ABSTRACT FROM AUTHOR]

Background Aim Methods Conclusions Lasers and other energy‐based devices are increasingly becoming popular in aesthetic practice. Many centers employ doctors or technicians to perform these procedures where treating doctor and operating doctor may be different. Hence the need for standard operative protocols, to be followed while performing these procedures to avoid mistakes, complications and to get optimum results. In the current review article, group of doctors who have worked with these energy‐based devices over many years worked together and suggested the protocols to be followed for the most commonly used energy‐based procedures.To provide Standard operating protocols for the operator and staff to ensure, efficacy, safety, for the patient and for the devices.The following protocols have been drafted based on the best practices followed by the authors in their clinics and reflect their consensus opinion. The objective is to provide operating protocols in a standard format, which can be of use by practicing dermatologists and their staff. The protocols include both general guidelines for the laser room and specific protocols for different machines. The draft follows the following schema: General instructions for all the energy‐based devices. Specific protocols for different devices: Laser hair removal, fractional lasers, Q‐switched lasers, fractional microneedling radiofrequency and cryolipolysis. The protocols proposed help to maintain the uniformity and avoid complications. However, these instructions are generalized and not machine or lesion specific. There may be variations in the protocols depending on the treatment lesion and treating doctor as well as machine. [ABSTRACT FROM AUTHOR]

Regarded as an essential transition metal, gold holds significant research value in the academic realm. In this work, gold nanoparticles were prepared by a combination of magnetron sputtering and liquid-phase exfoliation. The nonlinear optical properties of gold nanoparticles had been systematically investigated by utilizing the open aperture Z-scan method with both nanosecond and picosecond laser sources, which were rarely involved in previous studies. Based on the saturation absorption properties of gold nanoparticles, we prepared a gold saturable absorber and successfully applied it in generating passively Q-switched pulses in Pr:YLF crystal laser and Nd:YAG crystal laser, respectively. And we also analyzed its optical limiting applications. Our systematic study confirms that gold nanoparticles are suitable as candidates for saturable absorbers and optical limiting materials. [ABSTRACT FROM AUTHOR]

This work demonstrates the generation of a Q-switched laser in a neodymium-doped fiber laser (NDFL) cavity incorporated erbium oxide as a saturable absorber. NDFL pumped with 808 nm laser diode generated Q-switched pulses at the operating wavelength of 1088 nm without any filter due to a strong Nd3+ transition from 4F5/2 to 4I11/2 energy level. The pulsed laser exhibits stable Q-switching behavior within the pump power of 167.04–205.28 mW with the shortest pulse width of 2.41 μs. As the pump power adjusted in the same range, the repetition rate varied between 34.18 kHz to 41.72 kHz. The signal-to-noise ratio of 55.39 dB from the radio frequency analyzer indicates these pulses operate in a highly stable manner. In the authors' knowledge, this is the first demonstration of Q-switched NDFL utilizing erbium-oxide as SA device. [ABSTRACT FROM AUTHOR]

Remote detection of trace explosives and hazardous chemicals has been an ongoing challenge and a critical issue in defense science, public safety, and counterterrorism. Raman spectroscopy, a form of inelastic scattering, acts as a "fingerprint" analysis method for substance identification with high confidence in the detection of chemicals based on their vibrational modes. Here, we present a portable stand-off time-gated Raman spectroscopy, which consists of a passive Q-switched pulsed laser, a designed gated ICMOS, a spectrometer, and a telescope, with an overall size of 476.5 × 321.5 × 219.3 mm and a weight of 23.2 kg, which is much more compact and portable than reported previously. To confirm the effectiveness of the designed portable time-gated Raman spectroscopy, detections at different working distances and various amounts of substances are carried out. High levels of Raman identification are acquired even for 0.1 mg at a 10-m distance. Furthermore, we simulate realistic encounters in a possible war-zone scenario by testing the system's ability to recognize urea samples on different substrates such as an aluminum plate, woodblock, cardboard, black cloth, and leaf; good characteristic recognition is shown. [ABSTRACT FROM AUTHOR]

We report on the chaotic dynamics in a passively Q-switched 2.3-μm thulium laser operating on the 3H4 → 3H5 transition. The experiment exploits a Tm:LiYF4 crystal and various laser cavity configurations, involving an optional cascade laser on the 3F4 → 3H6 transition at 1.9 μm. The saturable absorber employed is Cr2+:ZnSe, which is exclusively saturated by the 2.3 μm laser. An analysis of the Q-switched dynamics shows a pronounced inclination of the laser operation toward the unstable and chaotic behavior. To understand the origins of this chaos, we monitor the population of the metastable 3F4 level via cascade laser operation at 1.9 μm, underlying this variable as an interesting parameter to survey chaotic instabilities. [ABSTRACT FROM AUTHOR]

We demonstrated a stable passively Q-switched fiber laser operation at 1531.57 nm using a double-transition metal MAX phase TiNbAlC saturable absorber. The prepared saturable absorber's modulation depth, saturation intensity, and non-saturation loss are 1.75%, 0.089 MW/cm 2 , and 32.81%, respectively. Using the TiNbAlC saturable absorber within an erbium-doped fiber laser ring cavity, stable Q-switched pulses with a central wavelength of 1531.57 nm, and a 3-dB bandwidth of 1.43 nm are acquired. The minimum pulse duration and the maximum single pulse energy are 3.18 μ s and 51.56 nJ, respectively. Furthermore, the maximum repetition rate is 37.9 kHz with a signal-to-noise ratio of 50 dB. Our results indicate that double-transition metal MAX phase TiNbAlC can be an excellent saturable absorber candidate for an ultrashort pulse fiber laser. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown and subsequent plasma are produced in ambient air in the proximity of an aqueous surface using a Nd:YAG Q-switched laser at 1064 nm with a pulse width of 9 ns and a delivered focused input energy of 170 mJ. The distance between the focal point of a 10 cm convex lens and the aqueous surface is 4 mm with laser propagation perpendicular to the surface. Using an intensified CCD camera attached to a 1-m spectrometer, spatial and wavelength-resolved plasma emission data are obtained for delay times after breakdown ranging from 50 ns to 10 μs with a gate window typically 5 ns. Plasma electron density is determined by applying Lorentzian fitting and FWHM extraction to three Stark-broadened spectral lines: N II 3P-3Do multiplet (593.85 nm), Hα (656.27 nm), and the Na D doublet (589.00 and 589.59 nm). One-dimensional spatially resolved measurements of the total emission intensity and electron density are obtained by binning the camera image along the laser axis in intervals of 250 μm and are reported as a function of time from 50 ns to 10 μs. Two plasmas are ignited from a single laser pulse; one from laser breakdown at the water surface and the other a few nanoseconds later from laser-induced air breakdown at the focal point of 4 mm above the water surface. Comparisons between the evolution of the air plasma near and far from the water surface are presented along with data for the water surface plasma itself. [ABSTRACT FROM AUTHOR]

Tattoo removal is considered a challenging field in cosmetic dermatology. Picosecond Q-switched Nd-YAG lasers targeting unique chromophores effectively manage this condition without serious complications. To evaluate the efficacy and safety of Picosecond Q-switched Nd-YAG laser in the treatment of black tattoos in the skin of middle eastern mostly skin type IV. The study was carried out on 20 patients with skin type IV the most common in middle eastern area with professional black tattoos. They were treated by Picosecond Nd-YAG laser (2 sessions 8 weeks apart). The percentage of improvement ranged from 20.0 to 95.0 (with a mean of 61 ± 24.6). 8 patients (40%) showed excellent improvement, 4 patients (20%) showed marked improvement, 4 patients (20%) showed moderate improvement, and 4 patients (20%) showed mild improvement. No severe side effects were detected. Picosecond Nd-YAG laser was an effective and safe technique in the treatment of professional black tattoos; with only 2 sessions most patients reached excellent to moderate response with minimal side effects. [ABSTRACT FROM AUTHOR]

In this paper, the end-pumped passively Q-switched Nd: KGW/Cr4+:YAG self-Raman laser is designed to achieve high efficient operation. Concave-plane linear cavity is adopted to obtain the shortest cavity length, and long Nd: KGW crystal of 40 mm is used in the experiment. Cr4+:YAG crystals of high initial transmittances (T0 = 96% and 92%) are utilized to realize efficient and stable passively Q-switched operation. The passively Q-switched Nd: KGW/Cr4+:YAG self-Raman laser is theoretically investigated at 1181 nm corresponding to the Raman mode of 901 cm− 1 shift in Nd: KGW crystal. With Cr4+:YAG crystal of the initial transmittance T0 = 96%, the maximum output power of 0.624 W at 1181 nm is achieved experimentally with optical-to-optical efficiency of 13.9%, which is the highest efficiency reported for passively Q-switched Nd: KGW self-Raman laser. [ABSTRACT FROM AUTHOR]

Enhancing the performance of saturable absorbers (SAs) crafted from two-dimensional (2D) narrow-bandgap materials is crucial for their use in ~ 2.0 µm pulse laser applications. In this context, a high-quality TaSe2 SA was successfully fabricated by mechanical exfoliation. The TaSe2 SA exhibited saturable absorption characteristics at around 2.0 μm, with a modulation depth of 7.1% and an unsaturated loss of 3.1%. Utilizing this newly fabricated SA, a passively Q-switched Tm:YAP laser operating near 2.0 μm was achieved. At the highest absorbed pump power of 5.58 W, the laser produced a maximum average output power of 1.34 W, with a pulse width measuring 550 ns at 89 kHz. This performance translates to a peak single pulse energy of 15.0 μJ and a maximum peak power of 27.27 W. [ABSTRACT FROM AUTHOR]

We report a 2.8 μm all-fiber high-power and high-energy gain-switched Er3+:ZBLAN laser based on dielectric fiber mirror and fiber-tip protection. The fiber pigtail mirror, specifically designed for dichroic operation (i.e., anti-reflection at 976 nm pump wavelength and high-reflection around 2.8 μm laser wavelength), shows high damage density of >10 MW/cm2. An anti-reflection protective film is coated on the input tip of Er3+:ZBLAN fiber and an AlF3 endcap is spliced to the output tip of Er3+:ZBLAN fiber for mitigating the fiber-tip photodegradation and high-power catastrophic failure at 2.8 μm. The compact all-fiber cavity is formed by efficiently connecting the Er3+:ZBLAN fiber with dielectric fiber mirror using the standard FC/PC fiber adaptor. When the 976 nm pump operates in pulsed regime, the all-fiber mid-infrared gain-switched laser can be attained with two states of single-pulse and pulse-burst output. The extracted maximum pulse energy is 4.8 μJ in the single-pulse state, and the shortest pulse width is 426 ns. The pulse-burst mode can generate a maximum average power of 5.291 W and burst energy of 264.55 μJ. This work may offer a promising way to realize the low-cost, all-fiber, high-power and high-energy gain-switched laser at MIR wavelengths. [ABSTRACT FROM AUTHOR]

A passively Q-switched Er:YAP laser of 2.7 µm, utilizing Au-doped CsPbI3 quantum dots (QDs) as a saturable absorber (SA), was realized. It was operated stably with a minimum pulse width of 185 ns and a maximum repetition rate of 480 kHz. The maximum pulse energy and the maximum peak power were 0.6 μJ and 2.9 W, respectively, in the Q-switched operation. The results show that the CsPbI3 QDs SA exhibits remarkable laser modulation properties at ~3 μm. [ABSTRACT FROM AUTHOR]

In this paper, we report a new model for passively Q-switched intracavity optical parametric oscillators (IC-OPOs), using Cr:YAG as a Q-switch crystal. The model considers the effects of thermalization in the Nd:YAG laser crystal, excited state absorption in the Cr:YAG saturable absorber, nonlinear loss due to pump depletion in the nonlinear crystal, the thermal lens effect and the mode overlap of the fields within the nonlinear crystal. The calculated pulse width for the 1,064 nm pump light was 6.2 ns compared to the experimental result of 6 ns, while the signal wave was calculated to have a pulse width of 1.75 ns compared to the experimental result of 2 ns. The model is shown to accurately calculate both the temporal and output power characteristics of the IC-OPO, which has not been previously reported to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Objective: To determine the effectiveness of picosecond KTP in reducing peri-ocular dark circles caused mainly by excessive pigmentation and to compare Picosecond KTP with Thulium laser ability in reducing the intensity and extent of peri-ocular dark circles. Materials and methods: This split-face prospective study included twelve women with periorbital dark circles (pigmented or mixed-pigmented type). The left lower eyelid was treated using the PicoHi machine (HIRONIC Ltd), a full beam Q-switched Nd-YAG provided by KTP crystal (523 nm) at settings of 0.3 J/cm2, 5 mm, 5 Hz, and 300 Ps. Whereas the right lower eyelid was treated using the Lavieen machine (WON TECH Co., Ltd), a fractional Thulium laser (1927 nm) at setting 1320 mJ/cm2, 30 × 15 mm, 1500 microseconds. Patients received a series of 3 treatment sessions, given at 4-week intervals. Results: The 532-nm full beam Q-switched KTP and fractional Thulium lasers were more likely to induce post-inflammatory hyperpigmentation rather than decrease the pigmentation. The risk is higher with a Q-switched KTP laser, which may be attributed to the skin tone of the participants. Nonetheless, some improvement in the pigmented type of PDCs, although not detected clinically, was documented by the VISIA software. Conclusion: No solid conclusion can be drawn from the results of the study. Picosecond KTP and Thulium lasers may have a role in reducing PDCs yet more studies should be performed in order to determine the exact impact these lasers have. [ABSTRACT FROM AUTHOR]

Pulsed laser ablation in liquid technique was used to produce nanostructure materials from a gold metal plate immersed in double distilled water at different energies (200 and 400 mJ) and different numbers of pulses (100, 200, 300, 400 and 500) using a Q-switched Nd:YAG laser. Moreover, the prepared gold nanoparticles (AuNPs) were tested and characterized using different examined techniques. The optical, morphological and structural properties of AuNPs were characterized by an UV-visible spectrometer, transmission electron microscope (TEM), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction. It was found that by increasing in the number of laser pulses before irradiation, the UV-visible spectroscopy revealed a decrease in the surface plasmon resonance (SPR) peak position and an increase in the optical band gap of AuNPs. TEM and FE-SEM images showed spherical-like shapes with average diameters ranging from 34 to 44 nm. AuNP face centered cubic crystallinity was evident from XRD. Moreover, antibacterial tests with AuNPs on Staphylococcus aureus and Escherichia coli showed a mid-level inhibition. In addition, the AuNP absorbance intensity and SPR peak at 522–525 nm increased after the UVC irradiation, while the optical band gap of the samples slightly decreased. The AuNP UVC-irradiation exhibited a significant inhibitory effect against Gram(+ve) and Gram(–ve) bacteria. [ABSTRACT FROM AUTHOR]

A master oscillator power amplifier (MOPA) pulsed laser operating at 1342 nm is demonstrated. It consists of an acousto-optical (A-O) Q-switched oscillator and two-stage Nd: YVO4 power amplifiers. The spherical aberration self-compensation technique is used in the second stage amplifier to obtain high-beam-quality laser output. The maximum average output power of 20.4 W is obtained with the oscillator power of 2.0 W and the total pump light power of 184.08 W, corresponding to an optical-optical efficiency of 11.08%. The repetition rate and pulse width are 100 kHz and 14.8 ns, respectively. The beam quality factor is Mx2=1.45 and My2=1.34. According to our knowledge, this is the maximum output power with a pulse width of ten-nanoseconds level and repetition rate of one-hundred-kilohertz level by an A-O Q-switch at the wavelength of 1342 nm. [ABSTRACT FROM AUTHOR]

Ta2NiS5 nanosheets were fabricated and analyzed for their microstructures and nonlinear optical responses. As a saturable absorber (SA), Ta2NiS5 was integrated into an idler-resonant KTiOAsO4 (KTA)-based intracavity optical parametric oscillator (IOPO) pumped by a dual-loss-modulated Q-switched YVO4/Nd:YVO4 laser. At an incident pump power of 18.9 W and an acousto-optic modulator (AOM) modulation rate of 4 kHz, the maximum output powers of 467 mW for the signal wave and 228 mW for the idler wave were achieved, corresponding to an overall optical-to-optical conversion efficiency of 3.68%. Remarkably, the shortest measured pulse widths of 872 ps for the signal wave and 2.86 ns for the idler wave were obtained, corresponding to the highest peak powers of 392 kW and 57.6 kW for the signal and idler waves, respectively. In comparison to the IOPO pumped by a singly Q-switched YVO4/Nd:YVO4 laser (SIOPO) with an AOM, the IOPO pumped by a doubly Q-switched YVO4/Nd:YVO4 laser (DIOPO) with an AOM and a Ta2NiS5 SA can generate signal and idler waves with significantly shorter pulse widths and higher peak powers. Additionally, the coupled rate equations for the idler-resonant DIOPO were given. The numerical simulations exhibited remarkable consistency with the experimental results. [ABSTRACT FROM AUTHOR]

In recent years, 2D Cr2S3 has earned lots of attentions in the fields of photocatalysis and photodetector due to its outstanding environmental stability and high responsivity. However, up to now, the optical properties of 2D Cr2S3, especially the NLO properties of Cr2S3 have been rarely studied. In this work, the NLO properties of Cr2S3-nanoparticles in 1 μm have been investigated by using open-aperture (OA) Z-scan method. The nonlinear absorption coefficient (β), modulation depth and saturable intensity are measured to be -2.6 cm/GW, 11.5%, and 0.115 MW/cm2, respectively. Furthermore, by depositing Cr2S3 nanoparticles on a side-polished fiber and inserting into a ytterbium-doped fiber laser (YDFL) cavity, stable mode-locking laser and Q-switching laser with a pulse width of 10.2 ns and 2.95 µs are achieved, respectively. These results demonstrate that Cr2S3 is a promising saturable absorber (SA) for the fiber laser applications. [ABSTRACT FROM AUTHOR]

A switchable and wavelength interval adjustable multi-wavelength erbium-doped fiber actively Q-switched fiber laser based on EOM and improved Lyot filter is proposed. In the experiment, stable and switchable laser outputs of single to quintuple-wavelength can be achieved by adjusting the polarization controllers and the wavelength intervals are adjustable between 2 nm, 3 nm and 6 nm. With the increase of the pump power, the number of output wavelength reaches nine. Moreover, the single-dual and dual-pulse sequences can be observed in a modulation period and the dual-pulse interval can be tuned from 14.7 to 11.1 µs. The wavelength interval of the proposed laser and the pulse interval of the dual-pulse can be adjusted more flexibly. It has a broad application prospect in the fields of optical measurement and laser imaging. [ABSTRACT FROM AUTHOR]

A compact three-band symmetrical triangular linearly frequency-modulated (TLFM) continuous-wave radar based on the gain-switched DFB laser is proposed in this paper. By introducing the low central-frequency TLFM signal with high-power to modulate the DFB laser, the DFB laser would enter into the gain-switching state and a coherent and stable three-band broadband TLFM signals (S-/C-/X-band) with a bandwidth of 0.4*N GHz (N = 1, 2, 3) would be generated after the photodetector. Based on this condition, one three-band TLFM continuous-wave radar system can be realized. The system does not require an external modulator in multi-band generation, and uses a single-channel transceiver module to achieve simultaneous transmission and echo dechirp processing of multi-band radar, which greatly reduces the deployment difficulty of the multi-band radar system, so the cost, size, weight and other characteristics of the system are expected to be reduced. In the current proof-of-concept experiment, the range resolution of the three-band TLFM signal can reach 13.8 cm, compared with the single-band TLFM signal which cannot distinguish the targets. [ABSTRACT FROM AUTHOR]

A Q-switched Nd:YAG laser was focused on the Pb–Ti alloy samples in several laser-induced breakdown experiments in order to measure the Stark parameters of several spectral lines (58) of singly ionized titanium, including the 3504.89 Å and 3510.83 Å lines (where we achieved new experimental and theoretical values). The diagnostics of the laser-induced plasmas (electron density and electron temperature) were performed using Balmer's H alpha line (6562.7 Å). The temperatures were obtained by the Boltzmann plot technique with spectral lines of Pb I (after correction for its evident self-absorption). Subsequently, the calculations by the Griem approach of the Stark broadening parameters for several spectral lines were performed using the Gaunt factors proposed by van Regemorter and those proposed by Douglas H. Sampson. In the latter case, the values obtained were very close to the experimental values. This enables us to assume that the calculations performed for the spectral lines of Ti II, without experimental information, are more accurate using the Gaunt factors proposed by Sampson. [ABSTRACT FROM AUTHOR]

Current trends in the development of materials for optics and laser technology were analyzed. The prospects of creating passively Q-switched Yb-Er glass lasers with eye-safe emission wavelengths based on glass-ceramic magnesium aluminosilicate materials for compact pulsed lasers were established. The main types of transparent glass-ceramic materials were analyzed and the main criteria for the synthesis of transparent nanostructured glass-ceramic materials with a crystalline phase content of approximately 70-80 vol.% were substantiated. Compositions of magnesium aluminosilicate glasses were synthesized and the differences of compositions with different types of optical transparency were determined, taking into account their thermal prehistory. The mechanism of phase formation and the differences of ΣMgO, Al2O3, MgO/Al2O3 and ΣRO2 in their composition, which determine the character of crystallization, optical transparency and density under the conditions of heat treatment with a duration of 0.5 and 6 hours, were studied. The developed magnesium aluminosilicate glasses can be used as a basis for the creation of protective and functional high-strength nanostructured glass-ceramic materials based on spinel or cordierite with adjustable optical transparency for optics and laser technology. [ABSTRACT FROM AUTHOR]

A silicon carbide (SiC) plasma has been produced by a Q-switched laser at 1064 nm, 3 ns pulse and 1010 W/cm2 intensity, in high vacuum to investigate the fundamental mechanisms of laser-semiconductor interaction. Although the high hardness and chemical stability restrain the SiC micromachining, it is a valuable semiconductor for devices working under extreme conditions.The plasma has been characterized by using time-of-flight (TOF) measurements of ions detected by an ion collector ring (ICR) and an ion energy analyzer (IEA). Fast CCD camera, quadrupole mass spectroscopy (QMS) and surface profiler have been employed to provide deep insights into the laser-SiC interaction mechanisms.Ion kinetic energies, charge states, plasma expansion velocity, ablation yield per laser pulse, plasma temperature and density have been measured.Applications of the laser-generated plasma are presented and discussed. [ABSTRACT FROM AUTHOR]

Simultaneous measurements using two Intensified Charge-Coupled Device (ICCD) cameras with two bandpass filters on laser-induced air plasma have facilitated the illustration of a two-dimensional temperature distribution within the plasma. In each pixel, the intensity captured by the ICCD cameras could replace the intensity measurements using a spectrometer in the two-line ratio method for temperature measurement. The plasma was produced by a 532 nm pulse from a Q-switched neodymium-doped yttrium aluminum garnet laser. The two ICCD cameras with the two bandpass filters simultaneously captured the plasma to measure emission intensities at two wavelengths. The two-line ratio method using N II lines was applied in each pixel to examine the two-dimensional temperature distribution. Two laser energies and focal lengths were utilized to ensure spatially and temporally consistent temperature results considering the characteristics of the plasma temperature at the experiment conditions. The signal-to-noise ratio increased with increasing the incident energy and decreasing the focal length. The highest temperature was observed at the high incident energy and the short focal length. The location in the plasma with the maximum temperature varied over time. The temperature significantly reduced with time at the long focal length and low incident energy. The plasma temperature was measured using the two-line ratio method with a spectrometer. Average emission intensity images at the two wavelengths were used to examine the plasma temperature. The results of the three temperature measurement methods were compared to evaluate the accuracy of the methods. Generally, in the three methods, the temperature changes were similar along the x-axis of the plasma. The temperature difference between the two-filtered imaging method and the spectrometer was between 1 and 7%. The temperature difference between the average image method and the spectrometer was between 1 and 10%. The two-filtered imaging method simultaneously captures spectral emissions at two wavelengths and hence effectively shows a two-dimensional temperature distribution. [ABSTRACT FROM AUTHOR]

Lasers of low-coherence have attracted the attention of researches since the first publications on this topic in the 1960s and up to the present time. Low-coherent quasi-continuous LD-pumped Nd:YVO4 and Nd:YAG lasers with ≈ 1 ms pulses of 1064 nm radiation at 10 Hz repetition rate and 21–47 W output power are reported. Spatial coherence of laser radiation was determined by the contrast C of speckle patterns, C = 0.02 - 0.1. These Nd-lasers optical efficiency is in the range 20%–50% (depending on the coherence level). The low coherence was obtained at multimode lasing in a plano-spherical resonator near its stability limit. Experimental data are commented on using the calculated dependences of the number of laser modes and the degree of coherence on resonator configurations and pump spot sizes. The achieved contrast values C < 0.03 are below the level of human perception and correspond to the level of spatial coherence typical for thermal sources of radiation. Possible applications of the developed low-coherent multimode Nd-lasers and directions for further research are discussed. [ABSTRACT FROM AUTHOR]

This paper demonstrates a laser diode double-ended pumped Yb: YAG rod regenerative amplifier (RA) with an average power of 37 W, which substantially exceeds the performance of previously reported bulk Yb: YAG medium RAs. Compared to other bulk Yb: YAG medium RAs, we have introduced several enhancements in thermal management, such as employing a double-ended pump to reduce the temperature gradient inside the crystal, and the cooling efficiency is significantly enhanced by designed heat sink. As a result, the thermal effect is effectively suppressed. The system attains high average output power and power stability (RMS = 0.56%) at a pulse repetition rate of 400 kHz. In addition, the output beam maintains excellent quality even under varying high pump powers, demonstrating an M 2 consistently below 1.1. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) violet phosphorus (VP) plays a significant role in the applications of photonic and optoelectronic devices due to its unique optical and electrical properties. The ultrafast carrier dynamics and nonlinear optical absorption properties were systematically investigated here. The intra- and inter-band ultrafast relaxation times of 2D VP nanosheets were measured to be ~6.83 ps and ~62.91 ps using the pump–probe method with a probe laser operating at 1.03 μm. The nonlinear absorption coefficient βeff, the saturation intensity Is, the modulation depth ΔR, and the nonsaturable loss were determined to be −2.18 × 104 cm/MW, 329 kW/cm2, 6.3%, and 9.8%, respectively, by using the Z-scan and I-scan methods, indicating the tremendous saturable absorption property of 2D VP nanosheets. Furthermore, the passively Q-switched Nd:YVO4 laser was realized with the 2D VP nanosheet-based SA, in which the average output power of 700 mW and the pulse duration of 478 ns were obtained. These results effectively reveal the nonlinear optical absorption characteristics of VP nanosheets, demonstrating their outstanding light-manipulating capabilities and providing a basis for the applications of ultrafast optical devices. Our results verify the excellent saturable absorption properties of 2D VP, paving the way for its applications in pulsed laser generation. [ABSTRACT FROM AUTHOR]

A low-energy, diode-pumped, solid-state passively Q-switched laser operating at a wavelength of 1535 nm has been demonstrated to trigger gas switches. This technology has the potential to bring significant improvements to the operation and reliability of compact pulsed power drivers. Compact pulsed power drivers are often required to operate for hundreds to thousands of shots without maintenance; thus, the reliable operation of the laser triggered switch is significant for the adoption of this technology. A primary limiter of spark gap lifetime is electrode erosion. In the case of a laser triggered switch where the laser is focused on one electrode, an additional source of erosion is the direct ablation of the electrode material by the laser. The micro-laser used in the previous experiments is very low energy, but over thousands of shots, it does damage directly to the target electrode. This damage could potentially interact with the erosion due to the current discharge and impact the operation of the switch. The focus of this paper is to describe experiments undertaken to assess this damage and quantify its effect on switch operation over many discharges at current and energy levels relevant to compact pulsed power systems. [ABSTRACT FROM AUTHOR]

Q-switched fiber lasers have become reliable light sources for generating high-energy pulses, which can be passively modulated by saturable absorbers with excellent nonlinear optical properties. The composite combining Ag and MXene exhibits a broadband nonlinear response and high modulation depth, making it a promising candidate for saturable absorbers in pulsed lasers. Herein, we demonstrate a Q-switched Tm:Ho co-doped fiber laser centered at 2 µm, where the Ag/MXene composite serves as a saturable absorber to generate pulses. The typical spectrum, pulse train, and radio frequency spectrum of Q-switched pulses were observed, in which the 60 dB signal-to-noise ratio was higher than that of 2 µm Q-switched fiber lasers based on other materials, demonstrating the stability of the output pulses. Additionally, the long-term stability of the laser was evaluated over 2 h, where the well-maintained central wavelength and output power also indicated the robustness of the Q-switched laser. Furthermore, the influence of the pump power on the parameters of Q-switched pulses was also investigated, which is conducive to control the output characteristics of lasers. Specifically, the pulse width of the Q-switched pulse decreased, while the repetition rate, output power, and single pulse energy all increased with the increase in pump power. These experimental results demonstrate the ability of Ag/MXene as a saturable absorber and show its potential for generating high-performance pulses in ultrafast lasers. [ABSTRACT FROM AUTHOR]

Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is successfully employed to determine the chemical composition of brass samples using the LIBS technique. The sample is irradiated with a Q-switched Nd: YAG laser with a pulse width of 5 ns to generate laser-induced plasma (LIP) on the sample surface. The time evolution spectra were recorded from the surface of the brass sample only with an accumulation of five laser shots to get one LIP spectrum. Time-resolved LIP spectra have been utilized to identify the most appropriate time window (where the plasma is optically thin and in local thermal equilibrium) suitable for CF-LIBS implementation. Stoichiometric ablation is also demonstrated for metallic brass samples with the aforementioned laser in the present study. To obtain definitive quantitative information from LIP, the characterization of the plasma, i.e., spectral line intensity, spectral line broadening, electron number density, and plasma temperature, has been analyzed in this paper. Based on two different CF-LIBS algorithms, the brass sample composition was determined and found to be in good agreement with the certified results. This paper also compares and contrasts both strategies, as well as discusses their place and importance. The results of the present manuscript illustrate the potential applicability of CF-LIBS for yielding precise and accurate compositions of brass. [ABSTRACT FROM AUTHOR]

The peculiar nonlinear optical responses of two-dimensional (2D) materials endow them highly attractive for photonics applications. This review systematically discusses the performance of pulsed lasers employing 2D materials as their modulation device. First, it is crucial to categorize 2D materials that can act as saturable absorbers, encompassing a range of substances such as Graphene, Black Phosphorus, Topological Insulators, MXene, and even heterojunction. Furthermore, a thorough investigation is conducted to analyze the performance indexes to study the nonlinear characteristics of 2D materials in the pulse generation. Especially, the focus is on the 1.5 μ m band ultrafast lasers utilizing 2D materials. This paper also provides a comprehensive analysis of the obstacles and prospects in 2D materials preparation, and their utilization in the pulse laser systems. [ABSTRACT FROM AUTHOR]

Background: To evaluate the efficacy and safety of stromal vascular fraction (SVF), platelet rich plasma (PRP), and 1064‐nm Q‐switched Nd:YAG laser in reducing nanofat treated dark circles and wrinkles under the eyes. Method: This study was a single‐blinded randomized clinical trial conducted on patients with suborbital darkening under the eyes that randomly divided into control and case groups. In the control group, 15 patients were treated with one session of nanofat injection only, and five patients of each intervention groups received one session of nanofat+SVF injection, nanofat+PRP injection, and nanofat injection+Nd:YAG laser, respectively. Assessments methods were (1) evaluation of the degree of darkness and repair under the eyes by a blinded dermatologist based on clinical photographs, (2) investigating patient satisfaction, (3) using biometric variables for color, thickness, and density of the skin (only 3 months after the treatment), and (4) recording the possible adverse effects. Conclusion: In terms of the extent of reduction in the intensity of darkness under the eyes, the combined treatment of nanofat injection together with SVF, PRP, and Nd:YAG laser had a much greater therapeutic effect than nanofat injection alone. In all three groups of combined treatments, patients were 100% satisfied. In terms of biometric variables, amount of changes in colorimeter, complete and dermal thickness, complete and dermal density, between the different groups was statistically significant. The use of combined treatments including nanofat with SVF injection, PRP, and 1064 Q‐switched Nd:YAG laser may be more effective than nanofat alone, in reducing infraorbital dark circles and wrinkles. [ABSTRACT FROM AUTHOR]

Nickel diselenide (NiSe2) microspheres were synthesized using a chemical vapor deposition (CVD) method, and their nonlinear optical properties were investigated. The prepared NiSe2 exhibits good nonlinear characteristics, demonstrating a high modulation depth and a low saturation intensity. Then the NiSe2 was used as a saturable absorber device and integrated into a 1.5 μm erbium-doped fiber laser to generate Q-switched pulse. By optimizing the cavity dispersion and adjusting the polarization state within the cavity, the single pulse tunable Q-switched pulse, Q-switched mode-locking pulse and quasi-mode-locked pulse based on NiSe2 saturable absorber are realized. Among them, the signal-to-noise ratio of the quasi-mode-locked pulse is as high as 68 dB, which proves that the resulting pulse has high stability. The findings of this study suggest that NiSe2 SA devices have the potential to be developed as highly efficient candidates for ultrafast photonics and can find extensive applications in nonlinear optical fields. [ABSTRACT FROM AUTHOR]

A nanophotonic passively Q‐switched lasing element in the near infrared is proposed and theoretically investigated. It consists of a silicon‐rich nitride disk resonator enhanced with the contemporary MoS2/WSe2$\left(\text{MoS}\right)_{2} / \left(\text{WSe}\right)_{2}$ hetero‐bilayer and a graphene monolayer to provide gain and saturable absorption, respectively. The two‐dimensional materials are placed on top of the disk resonator and are separated by a spacer of hexagonal boron nitride. MoS2/WSe2$\left(\text{MoS}\right)_{2} / \left(\text{WSe}\right)_{2}$ emits at 1128 nm due to the radiative recombination of interlayer excitons after being optically pumped at 740 nm. Optical pumping is conducted in a guided‐wave manner aiming at achieving a high overall efficiency by critically coupling to a cavity mode near the pump transition. The response of the proposed pulsed laser is assessed by utilizing a coupled‐mode theory framework fed with linear finite‐element method simulations, rigorously derived from the Maxwell–Bloch equations. Following a meticulous design process and exploiting the guided pumping scheme, an ultralow lasing threshold of just 24.2 $24. 2 \text{ } \mu \text{W} $μW is obtained. Overall, the Q‐switched laser delivers pulsed light inside an integrated bus waveguide with mW peak power, ps duration, and GHz repetition rates requiring sub‐mW continuous wave pumping. These properties are highly promising for communication applications and highlight the potential of two‐dimensional materials for nanophotonic light sources. [ABSTRACT FROM AUTHOR]

This paper describes a gain-switched Ho:YAG laser that emitted at 2089 nm, driven by an actively Q-switched Tm:YLF laser as the pumping source. The laser attained few ns short pulse durations with high energies at controlled repetition rates due to the active Q-switch pump source. Using the gain-switch method, stable short pulse durations ranging from 3.5 to 7.2 ns, with an energy per pulse of 0.4 to 0.52 mJ, were achieved at repetition rates of up to 2.5 kHz. This design can have significant advantages in various fields, where accuracy in the repetition rate is essential and a passive Q-switch cannot be implemented due to its accuracy limitations, including sensing, LIDAR, medical procedures, and material processing. [ABSTRACT FROM AUTHOR]

Nevus of Ota (NO), also known as "brownish-blue nevus of the palate of the eye", is a benign dermal pigmentation that increases skin disease. The Q-switched ruby laser is a classic treatment for nevus of Ota in children, but the optimal age for treatment is still controversial. The aim of this study was to investigate the treatment effect of Q-switched ruby laser in children with nevus of Ota at different ages and the effect on psychological health status. Materials and Methods: Children with nevus of Ota treated with Q-switched ruby laser in the Department of Dermatology of the Second Affiliated Hospital of Wenzhou Medical University from June 2015 to June 2019 were retrospectively analysed. And the mental health status was assessed using the CDI scale. Results: In the preschool children group (0– 7 year age), the significant efficacy rates was 93.1%, the average number of treatments was 3.6, and the overall incidence of adverse reactions was 4.7%. The significant efficacy rates in the school-age children group (7– 14 year age) was 90.3%, the average number of treatments was 5.1, and the overall incidence of adverse reactions was 13.7%. The mean post-treatment CDI score in the preschool children group was 10.8, and 9.7% of children exceeding 19 points. The mean pre-treatment CDI score in the school-age children group was 17.3, and 24.6% of children exceeding 19 points. The mean post-treatment CDI score was 13.6 and 15.1% of children exceeded 19 points. The chi-square test for the significant efficacy rate of the two groups showed P> 0.05, which was not statistically significant. The significant efficacy rate of the preschool group and that of the school-age children group. The t-test for the number of treatments in the two groups showed P< 0.05, which was statistically significant. Adverse reactions in the two groups showed a statistically significant P< 0.05. The mean CDI scores and the percentage of depressed individuals in the school-age children group were significantly lower after treatment than before treatment (p< 0.05). Conclusion: Q-switched ruby laser is safe and effective in treating nevus of Ota in children. Early treatment can reduce the number of treatments and the incidence of adverse reactions. In addition, early treatment can reduce children's depression, which is beneficial to mental health. [ABSTRACT FROM AUTHOR]

The laser drilling of carbon steel is always suffered from the formation of slag, the presence of cutting burrs, the generation of a significant quantity of spatter, and the incomplete penetration of the substrate. In order to avoid these defects formed during the laser drilling of carbon steel, the COMSOL multi-physics simulation method was used to model and optimize the laser drilling process. Considering the splash evolution of the material during the complex drilling process, the transient evolution of the temperature field, the flow of the molten fluid, the geometrical changes, and the absorption of the laser energy during the laser drilling process were investigated. The simulated borehole dimensions are consistent with the experimental results. The process parameters have a great influence on the fluid flow pattern and material slag splashing. The laser power has a significant effect on the laser processing compared with the process parameters. With the increase in laser power and the decrease in laser heat source radius, the time required for perforation is reduced, the flow of melt is accelerated, the perforation efficiency is increased, and the hole wall is smoother, but the degree of spattering is greater. The optimized process parameters were obtained: laser heat source radius of 0.3 mm, laser power of 3000 W. These findings can help reduce the machining defects in carbon steel with excellent mechanical properties by optimizing the laser drilling processing parameters. [ABSTRACT FROM AUTHOR]

Ultralow-noise microwaves are essential in a wide variety of scientific and technological applications, such as metrology, radars, and communications. Here, we propose and demonstrate a scheme for generating an ultralow-noise microwave signal using a Brillouin optical frequency comb (OFC), which is based on the stimulated Brillouin scattering in combination with a frequency-shifted optical injection locking mechanism. The generated two intra-cavity Brillouin lasers are used as the intra-cavity pump for the eventual formation of the OFC and thus the microwave signal via the cascaded four-wave mixing process. Exploiting the cascaded narrowing effect in the Brillouin cavity assisted by the frequency-shifted optical injection locking, the proposed microwave signal source exhibits ultralow phase noise. Experimental results show that the phase noise of the microwave signal is equivalent to below −115 dBc / Hz for a 200-GHz carrier at 10 kHz offset. The system can work in stable operation without the need for any active feedback loop. [ABSTRACT FROM AUTHOR]

Mid-infrared (MIR) pulsed lasers operating in the ∼3 μm region play a crucial role in various applications, including molecular spectroscopy, ultrafast molecular imaging, and laser-assisted surgery. Despite recent advancements in MIR gain platforms, a notable technological challenge remains in the absence of an effective optical Q-switch. Here, a remarkable optical Q-switch in the 3 μm region based on a Dirac semimetal PtTe2 saturable absorber is realized. By modulating the surface state of PtTe2, the pulsed laser exhibited an increase in average power, escalating from 521 to 588 mW, accompanied by a significant decrease in pulse width from 368 to 187 ns. Nondegenerate pump–probe measurements showed that the recombination rate of the photocarrier in thinner PtTe2 nanoplates was effectively accelerated, primarily attributed to the substantial increase in surface state density, leading to better saturable absorption performance. As the thickness of the PtTe2 nanoplates decreases, the nonsaturable loss decreases from 12% to 3%, while the modulation depth increases from 6% to 12%. The enhanced ultrafast nonlinear absorption enables flexible modulation of saturation absorption parameters, which endows high-performance MIR pulsed laser generation. [ABSTRACT FROM AUTHOR]