q switched laser

BACKGROUND: Keratosis pilaris is a common keratinization disorder of the extensor surfaces of the proximal extremities. Various treatment modalities reduce symptoms, but their efficacy is limited. AIMS: The aim of this study is to compare the efficiency of Q-Switched Nd: YAG laser and fractional Er: YAG laser. MATERIAL/METHOD: The lesions in both arms were randomly divided into areas A and B. Fractional Er: YAG 2940 nm laser performed to area A 1...

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In this work, we report the results of the compositional analysis of an aluminum gallium arsenide (AlGaAs) sample using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique. The AlGaAs sample was doped with three various concentrations of gallium (Ga), arsenic (As), and aluminum (Al), as reported by the manufacturer, and the CF-LIBS technique was employed to identify the doping concentration. A pulsed Q-switched Nd: YAG laser capable of delivering 200 and 400 mJ energy at 532 and 1064 nm, respectively, was focused on the target sample for ablation, and the resulting emission spectra were captured using a LIBS 2000+ spectrometer covering the spectral range from 200 to 720 nm...

BACKGROUND: Melasma is considered as a type of acquired facial pigmentary disorder that is challenging to treat. Low-fluence 1064 nm Q-switched Nd: YAG laser (LQSNY) has clinical benefits against melasma; however, there are some disputes. OBJECTIVE: To explore these contentious views, we conducted a meta-analysis and systematic review to evaluate the efficacy and safety of LQSNY monotherapy and combined therapy for the treatment of melasma. METHODS: The PubMed, Embase, Cochrane Library, and Web of Science databases were searched for relevant articles from inception to July 2021...

CdSiP2 (CSP) crystals have attracted increasing attention as efficient optical conversion media. Herein, the optical properties of a CSP crystal grown with the vertical Bridgman method are measured by a terahertz time-domain spectrometer (THz-TDS) at 0.2-3 THz. For the first time, to the best of our knowledge, the broadband, tunable, coherent, monochromatic THz radiation from 0.08 to 1.68 THz (3775-178 µm) is generated experimentally via this crystal, which is pumped by a nanosecond Q-switched Nd:YAG laser and an optical parametric oscillator (OPO) and based on difference frequency generation (DFG) technology...

The use of Q-switched erbium:yttrium-aluminum-garnet laser (Er:YAG laser), which have much less thermal effects than conventional Er:YAG lasers, has been proposed mainly in the medical field. The purpose of this study was to evaluate the bonding ability of dentin after Q-switched Er:YAG laser irradiation.The effects of dentin irradiation with Q-switched and conventional lasers were evaluated in terms of dentin morphology, roughness, hardness, elemental content, and resin bonding strength. Q-switched Er:YAG laser at average power densities of 20, 40, and 60 W/cm2 and conventional Er:YAG laser at 909 W/cm2 were used, and their performance was compared with that of the untreated group...

We demonstrate the first nanosecond pulsed single longitudinal mode (SLM) intracavity-pumped diamond Raman laser, to the best of our knowledge. The eye-safe coherent source at 1634 nm, which was converted from the actively Q-switched 1342 nm Nd:YVO4 laser, yielded 4.35 W of multimode average output power with a pulse duration of 6 ns and peak power of 29 kW. By exploiting the spatial hole burning free gain mechanism in the Raman media, stable SLM operation was observed at low output power (0.46 W) for the free-running case...

Conventional defect modes in all-dielectric 1D photonic crystals (PCs) are polarization-insensitive. This poses a great challenge in achieving high-performance polarization selectivity. In this Letter, we introduce a defect layer into a 1D PC containing hyperbolic metamaterials to achieve an anomalous defect mode with polarization-sensitive characteristics. As the incident angle increases, such a defect mode remains almost unshifted under transverse magnetic polarization, while strongly shifting toward shorter wavelengths under transverse electric polarization...

We present the case of a 16-year-old boy with Peutz-Jeghers disease with successful treatment of oral lentiginosis with one session of picosecond 755-nm alexandrite laser. To date, only in one other article picosecond laser is used for lentiginosis in Peutz-Jeghers disease. Other therapeutical options include Q-switched 755-nm alexandrite, 1064-nm Nd:YAG, 532-nm KTP-laser, ruby and intense pulsed light, which generally require more sessions, are less pigment-selective and have overall worse results than picosecond laser treatment...

We developed a visible-red to near-infrared wavelength tunable all-solid-state laser system utilizing an optical parametric generation process in a MgO doped PPLN crystal pumped at 532 nm by an amplified and frequency doubled picosecond passively Q-switched Nd:YVO4 microchip laser. A broad bandwidth, tuneable over 300 nm between 710 nm to 1015 nm, is accessible. Depending on the green pump light pulse energy, pulses with durations down to 69 ps as well as pulses with energies above 2 µJ were achieved with kHz repetition rates...

We demonstrate a thulium-doped fiber laser that is mode-locked thanks to nonlinear polarization rotation (NPR) in a chalcogenide tapered fiber. The high nonlinearity of the tapered fiber leads to a combined reduction in mode-locking threshold power and cavity length compared to any all-silica NPR based mode-locked lasers. In the continuous wave mode-locking regime, the laser generates stable, tunable solitons pulses. In the Q-switched mode-locked regime, it allows single and multiwavelength pulses, tunable central wavelength and tunable multiwavelength separation...

The laser shock peening process (LSP), used to reinforce metals, currently has two major configurations with limitations. (1) Laser irradiation with large spot sizes, but with the need to use a thermal protective coating to avoid detrimental thermal damage (which increases the overall cost of the process) or (2) laser irradiation without thermal coating but with very small spot sizes and high overlap ratios, thus increasing the amount of time required to treat a given surface. In this study, we develop a new faster configuration for the LSP process, which can be applied without a thermal coating, but is still effective regarding surface treatment time...

We propose and demonstrate an all-fiber passively Q-switched laser generating a third-order orbital angular momentum (OAM) pulse by introducing a few-mode long-period fiber grating (LPFG) into the laser cavity. The LPFG with asymmetric cross structure and strong refractive index modulation overcomes the coupling issue between the fundamental and the third-azimuthal-order (LP31 or OAM3 ) modes and realizes their direct conversion. A homemade graphene-based saturable absorber is used to realize Q-switched operation...

Pulsed lasers operating in the mid-infrared are of great importance for numerous applications in spectroscopy, medical surgery, laser processing, and communications. In spite of recent advances with mid-infrared gain platforms, the lack of a capable pulse generation mechanism hinders the development of compact mid-infrared pulsed laser source. Here we show that MIL-68(Al) and MIL-68(Fe), which are aluminum- and iron- based metal-organic frameworks (MOFs) with ordered atoms distribution and periodic mesoporous structure, constitute exceptional optical switches for the mid-infrared...

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Two-dimensional (2D) materials show great promise as saturable absorbers (SAs) for ultrafast fiber lasers. However, the relatively low modulation depth and poor stability of some 2D materials, such as graphene and black phosphorus, restrict their applications in the mid-infrared pulse generation. Herein, we first report a novel 2D double transition metal carbide, denoted as Mo2 Ti2 C3 Tx MXene, as the saturable absorber (SA) for a passively Q-switched mid-infrared fiber laser. Due to the unique four-metal atomic layer structure, the Mo2 Ti2 C3 Tx exhibits superior saturable absorption properties, particularly with a higher modulation depth (40% at 2796 nm) than most of the other reported 2D SA materials...

In this work, we used nanocomposite Saturable absorbers (SAs) in order to precisely design and modulate the process of compositing the light absorption by band gap engineering. Due to the higher absorption intensity of our MoS2/MXene nanocomposite, we have successfully shortened the pulse duration (1.2 μs) of SA with enhancing saturable absorption intensity (7.22 MW/cm2), and the ultra-fast fiber laser based on this nanocomposite SA has shown wider Q-switching stable range in the case of high pump power. This strategy can efficiently improve the performance of SA and shows the potential application prospect of nanocomposites in nonlinear optics...

OBJECTIVE: To evaluate the efficacy and safety of 585 nm Q-switched laser in the treatment of acne inflammatory lesions and postinflammatory erythema. METHODS: A total of 25 patients with moderate facial acne, symmetrical distribution of inflammatory lesions and postinflammatory erythema on both sides of the face, were enrolled. Among the 25 patients, 22 patients completed all the treatment and evaluation, and 3 patients were lost to follow-up. 585 nm Q-switched laser was used on a randomly selected side of the face for three times of treatment at a 2 week interval...

A femtosecond Mamyshev fiber oscillator in normal dispersion mode at 1 µm was started reliably and safely by an inexpensive diode-pumped passively Q-switched monolithic microchip laser emitting 300-ps pulses. Four-wave mixing spectral broadening is shown to play a pivotal role in starting the Mamyshev oscillator, owing to the random short and intense temporal fluctuations allowed by its ∼10-nm bandwidth. Systematic studies of the starting dynamics show that a success rate of 100% of the attempts is achieved with modest seed energy, as low as ∼30 nJ from the sub-nanosecond laser, corresponding to ∼100 pJ for the total four-wave mixing signal required to start the oscillation...

Labial lentigines associated with Peutz-Jeghers syndrome are challenging and represent a cosmetic problem. Laser and intense-pulsed light sources (IPLS) can be used to treat these macules. However, there are few guidelines regarding the different types of protocols found in the literature. Thus, the purpose of this study was to review the pertinent literature on lasers and IPLS as therapy for labial lentigines in patients with Peutz-Jeghers syndrome. A detailed literature search was conducted in seven databases (Cochrane Library, Embase, Lilacs, PubMed, SciELO, Scopus and Web of Science) to November 2020...