Q-switched Research Articles

Production of Cu/Zn Nanoparticles by Pulsed Laser Ablation in Liquids and Sintered Cu/Zn Alloy

As a preliminary step to establish technology for fabricating High-Entropy Alloys (HEAs) that can make a large-scale HEA using a pulse laser with high peak intensity and high-repetition in the future, we fabricated alloys in which two types of metal atom are mixed close together in the order of nanometers. For the method to produce the alloy, metal alloy nanoparticles were prepared by irradiating the material in liquid with focused high-repetition Q-switched laser pulses using an in-liquid laser ablation method. When brass powder was used as an original material, analysis results by TEM showed that numerous nanoparticles mixed with copper and zinc atoms could be produced. Furthermore, it was clarified by SEM EDS that copper and zinc atoms in the nanoalloy were maintained at a ratio of 3:1 in sintered alloy, and that the atoms were spatially uniformly distributed over a wide range in sintered metal.

In-band pumped, Q-switched thulium-doped fiber laser system delivering 140 W and 7 mJ pulse energy.

We report on a highly efficient, in-band pumped, Q-switched, Tm-doped, rod-type master oscillator power amplifier (MOPA) system delivering up to 140 W average output power and 7 mJ pulse energy with a slope efficiency of 77% at 20 kHz repetition rate. The amplifier is pumped with Raman-shifted fiber lasers centered at 1692 nm. This in-band pump scheme for Tm-doped fiber lasers can significantly mitigate their quantum defect-related heat load limitations. At the same time, this pump wavelength yields a similar amount of storable and extractable energy to the state-of-the-art pumping at 793 nm. This approach has allowed for the development of highly efficient Tm-doped fiber laser systems combining a high average power and a high output pulse energy.

Graphdiyne-Based All-Optical Modulator for an Actively Q-Switched Fiber Laser

Graphdiyne-Based All-Optical Modulator for an Actively Q-Switched Fiber Laser

Comparing optical deposition and drop casting for enhanced tunability in Q-switched fiber lasers using a biogenic AgNPs-CS saturable absorber

This study presents the successful synthesis and characterization of silver nanoparticles (AgNPs) using Camellia sinensis (CS) leaf extract as a biogenic saturable absorber (SA) for tunable Q-switched applications. The AgNPs-CS SA was fabricated through optical deposition and drop casting methods into a fiber ferrule. The nonlinear optical properties of AgNPs-CS as SA were investigated, revealing a modulation depth of 24.37% and a saturation intensity of 0.15 MW cm−2. Q-switching based on optical deposition exhibited a pump power of 213.40 mW, a 3-dB bandwidth of 3.20 nm, a pulse repetition rate of 78.74 kHz, and a pulse duration of 2.38 μs. Meanwhile, the drop casting method showed a 3-dB bandwidth of 2.0 nm, a pulse repetition rate of 53.05 kHz, and a pulse duration of 5.53 μs for the Q-switched pulse. Additionally, the tunability of wavelength in Q-switching using AgNPs-CS SA was investigated. The drop casting method achieved a tuning range of 32.00 nm, covering the S-band to C-band, while the optical deposition technique resulted in a tuning range of 54.20 nm, spanning from the C-band to L-band. Notably, this work represents the first utilization of AgNPs synthesized with leaf extract as a biogenic SA in the tunability of Q-switched lasers, employing two distinct fabrication techniques for the SA.

Narrow bandgap two-dimensional Nb2SiTe4 as broadband saturable absorber for optical switch

Nb2SiTe4 is a novel narrow-bandgap (∼0.39 eV) two-dimensional material with a high optical absorption coefficient, high carrier mobility, and outstanding air stability, which shows great application potential in broadband optical switches. In this study, high-quality layered Nb2SiTe4 nanosheets were efficiently fabricated by the mechanical exfoliation method, and the basic characterizations were carried out comprehensively. Nondegenerate pump-probe technology was implemented to systematically explore the photocarrier dynamics in the Nb2SiTe4 nanosheets, which exhibit the ultrafast recovery time of Nb2SiTe4 (∼0.3 ps). Furthermore, broadband passively Q-switched lasers operating at 1.0, 2.0, and 2.8 μm with the shortest pulse width of 380, 549, and 218 ns were achieved based on Nb2SiTe4 saturable absorber. This work demonstrates the significant advantages of an optical switch based on Nb2SiTe4 saturable absorber, including a narrow output pulse width, wide working bandwidth, high damage threshold, excellent oxidation resistance, and a straightforward synthesis method, which underscore the immense potential of Nb2SiTe4 broadband optical switches in applications involving mid-infrared lasers.

Evaluation of the effectiveness of picosecond KTP and fractional thulium lasers on pigmented-type periorbital dark circles.

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. 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 (523nm) at settings of 0.3J/cm2, 5mm, 5Hz, and 300 Ps. Whereas the right lower eyelid was treated using the Lavieen machine (WON TECH Co., Ltd), a fractional Thulium laser (1927nm) at setting 1320mJ/cm2, 30 × 15mm, 1500 microseconds. Patients received a series of 3 treatment sessions, given at 4-week intervals. 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. 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.

Generation of wavelength-switchable nanosecond mode-locked pulses in an Erbium/Ytterbium co-doped fiber laser cavity

This article experimentally demonstrates the generation of mode-locked (ML) pulses, which can operate either at 1568 nm or 1608 nm in an Erbium/Ytterbium co-doped fiber laser cavity (EYDF). The wavelength switching was achieved by adjusting the cavity loss. Depending on the cavity length and losses, the laser could operate in either mode-locked (ML) or Q-switched (QS) regimes. We explored the characteristics of the QS and ML pulses, based on the pump power, cavity length and loss. The laser produced stable QS pulses with a repetition rate of 22.73 kHz and a width of 12.2 μs at a pump power of 3.1 W at 1608 nm, for a 30 m long cavity. The laser produced 520 ns ML pulses at 1568 nm with a repetition rate of 877 kHz, average output power of 2.15 mW, and energy of 2.45 nJ with an additional single-mode fiber (SMF) length 200 m at the same pump power. The laser could switch to 1608 nm wavelength when the cavity losses were adjusted.

Study of the phase formation of transparent magnesium aluminosilicate glass-ceramic materials

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 MgO, Al2O3, MgO/Al2O3 and RO2 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.

Compact Q-switched vortex waveguide laser modulated by buried Ag nanoparticles in SiO2

Vortex beam, particularly pulsed vortex laser, has expanded the potential applications in optics due to their unique wave-front phase structure and the determined photon orbital angular momentum. In this study, we present a novel approach including the integration of fused silica embedded with silver nanoparticles (Ag:SiO2) into the Nd:YAG waveguide platform for achieving nanosecond vortex pulses. Using a spiral phase plate for in-cavity phase modulation, we successfully demonstrate a Q-switched vortex laser with a high repetition rate in the megahertz range and short pulse width in the nanosecond regime. Additionally, we conduct a comprehensive analysis of the near-field distributions of Ag nanoparticles with varying sizes and distributions using COMSOL simulation. This study exemplifies the integration of silica-based photonic elements for realizing a high-stability and cost-effective nanosecond vortex laser system.

Highly sensitive adulteration detection in kelulut honey utilizing fiber Bragg grating technology with Q-switched pulse erbium-doped fiber laser and innovative spider silk substrate

The growing field of photonics has seen significant developments in optical pulse fiber-based sensing technologies. In this research, a novel fiber Bragg grating using a Q-switched erbium-doped fiber laser source and innovative spider silk as a base material is presented, specifically designed for the detection of adulteration in pure kelulut honey. Kelulut honey has attracted much attention from Malaysian researchers as it is a highly prized, versatile local health remedy. During the experimental setup, concentrations of the adulterant isoglucose ranging from 0 % to 8 % and 10–50 % were intentionally added to the pure kelulut honey. The sensor showed remarkable sensitivity and detected subtle shifts in both the wavelength and radio frequency spectrum. The experimental results obtained emphasize the effectiveness of the proposed sensor and demonstrate its exceptional sensitivity in detecting adulteration in pure kelulut honey. This inherent property makes the derived pulse fiber laser sensor a promising tool for various applications in clinical detection and diagnosis as well as in the food industry. The results presented here not only contribute to the field of photonics but also have the potential to advance the quality control and authenticity assessment of kelulut honey in various fields.

Preparation, characterization of violet phosphorus and its application in fiber laser

Violet phosphorus (VP) is a new type of two-dimensional nanomaterial that has unique electronic and optoelectronic properties, and has gained wide attention in the fields of physics, chemistry, and materials science. However, only a few instances of the use of VP in fiber lasers have been demonstrated. For instance, VP films have been utilized as saturable absorbers in Q-switched ytterbium-doped fiber lasers (YDFL) and erbium-doped fiber lasers (EDFL), operating at central wavelengths of 1033 nm and 1560 nm, respectively. Herein, VP films are prepared using a liquid phase exfoliation method and introduced in the ring cavity of a YDFL. Increasing the pump power from 113 mW to 245 mW, and repetition rates from 32.33 kHz to 107.12 kHz, resulted in a stable sequence of Q-switched pulses. A pulse width of 2.9 µs is obtained at a pump power of 245 mW. At a pump power of 230 mW, the pulse energy is 31.02 nJ. In the case of EDFL, stable Q-switched pulses are obtained at a maximum pump power of 150 mW, with the repetition rate, pulse width and pulse energy being 63.51 kHz, 6.4 µs, and 102.19 nJ, respectively. These results indicate that VP may be a promising broadband SA suitable for fiber lasers with wavelengths of 1 µm and 1.5 µm.

Multivariate optimization effectiveness model of single-longitudinal-mode laser under pre-laser Q-switching regime

The optimal effectiveness model for optimizing the system parameters was established in this study by combining the optimization function based on the pre-laser Q-switching technique. By introducing boundary conditions to solve the rate equations, the specific process of composite mode selection is analyzed, and the specific pre-laser modulation time interval that enables single-longitudinal-mode laser output is obtained. Furthermore, through the established efficiency evaluation function for single-longitudinal-mode laser output characteristics, with the maximization of single-pulse energy as the objective, an energy efficiency analysis of relevant parameters in the mode selection components is conducted. The model we have established is universal, which can accurately control the pre-laser Q-switching process and reveals the inherent logical relationship of the relevant parameters in composite mode selection. The output characteristics of a single-longitudinal-mode Q-switching laser can be predicted and adjusted under the condition of high pump injection. Both simulation and experimental results confirm the effectiveness of the model.

SiC plasma characterization produced by 3 ns pulse laser at 1010 W/cm2 intensity

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.

Switchable Dual-Wavelength Q-Switched Erbium-Doped Fibre Laser using Spider Silk as a Biocompatible and Eco-Friendly Saturable Absorber

Switchable Dual-Wavelength Q-Switched Erbium-Doped Fibre Laser using Spider Silk as a Biocompatible and Eco-Friendly Saturable Absorber

Electro-optical Q-switched laser array with one lamp pumping six Nd:YAG rods for programmable laser reconstruction in space-power-time domains

We report a novel laser array with one lamp pumping six Nd:YAG rods for programmable laser reconstruction in space-power-time domains. A sextuple ellipse pump cavity is proposed, and this scheme permits one xenon flash lamp with advantageously cylindrical pumping characteristics to simultaneously efficiently pump multiple Nd:YAG lasers in a laser system. The experimental setup was designed, and further experiments were carried out. The laser array can stably operate at a pumping rate of 1 Hz-10 Hz. Each laser beam of the six laser outputs has a divergence angle of less than 1.7 mrad, an output pulse of greater than 208 mJ, and a pulse width of approximately 10 ns, corresponding to a pulse peak power of approximately 20 MW. The laser array has a total output energy of 1.53 J at an electrical input of 93.3 J, corresponding to an overall electro-optical conversion efficiency of 1.64 % and an electro-optical slope efficiency of 3.17 %. Finally, laser array output pulses coded modulation in the space-power-time domains are achieved by electro-optical Q-switching. Therefore, the laser array provides the capability for programmable laser reconstruction in the space-power-time domains in a laser system for multipurpose applications, such as energy-tailored material processing, coded pulse laser ranging for improved signal-to-noise ratio (SNR), active optical remote sensing and scientific research.

Diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm

A diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm based on 3H4→3H5 transition is proposed for the first time according to the references. The max mean output power of 0.41 W with a slope efficiency of 14.1% was obtained under the absorbed pump power of 6.7 W, corresponding pulse width and pulse repetition frequency were 7.82 μs and 45.09 kHz respectively. By analyzing the laser beam spatial distribution, the self-Q-switched Tm:YAlO3 laser at 2362 nm was originated from the time-dependent lens mechanism. The present research provides an approach for generating Q-switched lasers in the 2.3 μm spectral region.

CH3NH3PbBr3 as a saturable absorber for infrared passively Q-switched solid-state laser

Perovskite materials are used in the field of lasers and can achieved good results. In this paper, we prepared an organic–inorganic hybridized CH3NH3PbBr3 saturable absorber (SA). Continuous wave (CW) Tm:YAP solid-state lasers with CH3NH3PbBr3-SA successfully obtained pulsed lasing at 1987.5 nm after continuous tuning. In CW mode, the maximum absorbed pump power by the laser was 19.42 W, which corresponds to 0.68 W output power. The central output wavelength of the continuous wave laser was 1989.9 nm. In PQS mode, the output power of laser was 203 mW. Under the condition of maximum repetition frequency of 45 kHz, the narrowest pulse width of the PQS laser were 1.16 μs. Meanwhile, the laser produced a maximum single-pulse energy (4.5 μJ) and a maximum peak power (3.9 W). The beam quality factors (the horizontal/vertical directions) were M2 x = 1.1 and M2 y = 1.39. The CH3NH3PbBr3 was an excellent SA for infrared PQS solid-state lasers, which had a large potential for development applications in the field of lasers.

Switchable and wavelength interval adjustable multi-wavelength actively Q-switched fiber laser based on EOM and improved Lyot filter

Switchable and wavelength interval adjustable multi-wavelength actively Q-switched fiber laser based on EOM and improved Lyot filter

Theoretical and experimental investigations on idler-resonant intracavity KTA OPO pumped by a dual-loss-modulated Q-switched laser with AOM and Ta2NiS5 nanosheets

Theoretical and experimental investigations on idler-resonant intracavity KTA OPO pumped by a dual-loss-modulated Q-switched laser with AOM and Ta2NiS5 nanosheets

Passive mode-locking and Q-switching of ytterbium-doped fiber lasers using Cr2S3 saturable absorbers

Passive mode-locking and Q-switching of ytterbium-doped fiber lasers using Cr2S3 saturable absorbers