Q-switched Nd3 Research Articles

Self-illuminated third-harmonic image upconversion.

We demonstrate third-harmonic upconversion imaging to visualize real time infrared images in the visible with standard CCD or CMOS silicon-based cameras operating at room temperature. Different from the usual sum-frequency mixing image upconversion, our third-harmonic image upconversion approach does not require an auxiliary IR source to illuminate a target. The upconversion system uses a passively Q-switched Nd3+:YVO4 laser operating at 1342 nm with two intracavity KTP crystals, obtaining a 447 nm upconverted image by a cascaded process where an upconverted image at 671 nm is also obtained as an intermediate step.

Highly Conducting Sc and Y co-doped Zirconia Solid Electrolyte Thin Films Prepared via Pulsed Laser Deposition for Solid Oxide Electrochemical Cells Applications

Scandium (Sc) and yttrium (Y) co-doped ZrO2 thin films were fabricated via pulsed laser deposition (PLD). The target material, 4 mol% Sc2O3 and 4 mol% Y2O3 co-doped ZrO2 (ScYSZ), was first synthesized via a solid-state reaction. The ScYSZ thin film was deposited on SiO2-Si substrate by laser ablation, using a Q-switched Nd3+:YAG laser (λ = 266 nm) and substrate temperatures of 600 and 800 oC. Micro-structural and conductivity properties of the resulting as-deposited thin films were investigated. X-ray diffraction (XRD) sample patterns revealed that the as-deposited polycrystalline films can be indexed to a cubic structure. In addition, varying the oxygen partial pressures during the deposition was studied. FE-SEM images revealed dense and crack-free surface morphologies achieved at lower oxygen partial pressures (0.01 Pa and 0.1 Pa) and rough surface with porous morphology at high oxygen partial pressures (1.0 Pa and 10 Pa). The thickness of the film is about 120 nm for the thin film deposited at 800 oC substrate temperature (TS). The total conductivity of the thin film was measured using electrochemical impedance spectroscopy (EIS). Interestingly, the calculated total conductivity of the deposited ScYSZ thin film, 0.1 Pa and TS at 800 oC, revealed about 2.8x10-1 S/cmat 700 oC and with activation energy (Ea) of 0.78 eV from 500 oC to 700 oC. The fabricated as-deposited ScYSZ thin film is one of the highest reported highly conducting solid electrolytes that is a promising material for fuel cell or electrolysis cell applications.

Spectroscopic Diagnostic of Laser-Induced Zn Plasma

The sample's physical characteristics and laser parameters impact the generation and characterization of Laser-Induced Plasma (LIP), which is a relevant phenomenon in many applications. We investigated the effect of laser energy on laser-induced Zn plasma characterization in this study. A Zn plasma with a repeating frequency of 6 Hz, a first wavelength of 1064 nm, a pulse duration of 10 ns, and a laser energy range of 300 mJ to 500 mJ was created using a Q-switched ND: YAG laser. The basic plasma properties, such as electron temperature and density, were estimated using optical emission spectroscopy (OES). The electrons' temperature was measured by the Boltzmann plot method, and the value of the electrons' temperature ranged from 1.6 eV to 2.051 eV in the laser energy range (300-500) mJ. In electron density estimation using the Stark broadening methods, the density value range from 12.75×1017 cm-3 to 19.50×1017 cm-3, in laser energy range (300-500 ) mJ. In addition, various plasma characteristics such as plasma frequency (fp), the number of particles in the Debye sphere (ND), and Debye length (λD) were estimated. We found that laser energy affects every plasma parameter.

Laser Pulse’s Frequency Effect on Plasma Parameters for Titanium Dioxide Produced by FHG of a Q-Switched ND: YAG Pulse Laser

This work studies the relationship between laser irradiance and pulse frequency effect on plasma features of the TiO2. This target was irradiated by a Q-switched nanosecond Nd: YAG laser with the first harmonic generation (FHG) wavelength (1064[Formula: see text]nm), laser energy 500[Formula: see text]mJ, and pulse frequency ranging from 6[Formula: see text]Hz to 10[Formula: see text]Hz at atmospheric pressure. The Boltzmann plot and the Stark broadening methods calculated the plasma parameters ([Formula: see text] and [Formula: see text]. The findings were examined in light of the previously published experiments and theories, and it was discovered that they agreed with the hypothesis of the local thermodynamic equilibrium (LTE); on the other hand, research was conducted on the other basic plasma properties such as the Debye length ([Formula: see text]), the Debye sphere ([Formula: see text]), and the plasma frequency ([Formula: see text]). We observed that all plasma parameters are influenced by pulse frequency. The results clarify the linear change in electron temperature at increasing pulse frequency for TiO2 plasma. In contrast, the broadening of the line profiles related to electron density was evident with pulse frequency, causing an increase in electron density.

Sub-nanosecond, 41 mJ pulse energy, passively Q-switched Nd:YLF laser

A sub-nanosecond, diode-stack side-pumped, passively Q-switched Nd3+:YLF4/Cr4+:YAG Laser is reported in a compact cavity design, generating one pulse of 41 mJ with a pulse width of 894 ps, achieving a peak output power of 46 MW and beam quality M2 of 5.4 × 5.9 (HxV). The number of pulses in the pulse train could be adjusted from one pulse to ten pulses of 111 mJ total output energy and 23.7 % optical efficiency by adjusting the focus distance while maintaining sub-nanosecond pulse duration. This resonator can also be used for high-power simultaneous Q-switched laser emission at 1047 nm and 1053 nm.

The impact of yttrium aluminum garnet stoichiometry deviation on the conversion efficiency of tetravalent chromium ions

In this work, the conversion efficiency of Cr4+ ions and the optical properties of ceramics based on chromium-doped yttrium aluminum garnet were investigated. Increasing the conversion efficiency of Cr3+ to Cr4+ opens up broad prospects for using YAG ceramics as saturable absorbers for passive Q-switching of Nd- and Yb-solid-state lasers. The aim of this work was to study the effect of magnesium oxide concentration on the conversion efficiency of Cr3+ to Cr4+ under conditions of Al3+ (4.8 mol.%) and Y3+ (2.9 mol.%) cations excess in the garnet structure as well as the stoichiometric ratio Y3+/Al3+ = 3/5. The possibility of changing the concentration of Cr4+ ions in both the octahedral and tetrahedral positions due to the formation of magnesium substitution defects when the composition deviates from the yttrium-aluminum garnet stoichiometry has been studied. Chromium-doped transparent optical ceramics based on yttrium-aluminum garnet with different ratios of Y3+/Al3+ cations was obtained by the two-stage coprecipitation method. Magnesium oxide was used as a sintering additive and charge compensator for converting chromium ions from the trivalent to the tetravalent state in concentrations of 0 to 0.2 wt.%. It was found that aluminum excess in the yttrium-aluminum garnet matrix leads to a decrease in the Cr3+ to Cr4+ conversion efficiency. A deviation of stoichiometry towards an excess of yttrium leads to a decrease of air annealing temperature for oxidizing chromium ions to the tetravalent state and their transition to the tetrahedral position. However, the samples optical transmittance with an excess of yttrium was lower than in the cases of an excess of aluminum and stoichiometry. It was found that with an increase in the vacuum sintering temperature from 1780 to 1820 °C in the samples with an excess of aluminum, an increase in the concentration of Cr4+ ions in the tetrahedral position occurs, as evidenced by higher absorption intensity at a wavelength of 1030 nm. For the cases of stoichiometry and an excess of yttrium in garnet, this effect is less pronounced. Samples of optical ceramics of yttrium-aluminum garnet with a light transmission of more than 75 % in the visible and near-IR ranges with pronounced absorption bands of chromium have been obtained. The results of the work can be applied to the creation of passive switches for solid-state lasers.

Evaluation of Efficacy and Safety of Low-Fluence Q-Switched 1064-nm Laser in Infra-orbital Hyperpigmentation Based on Biometric Parameters.

Introduction: Dark circles and wrinkles under the eyes are common cosmetic problems, caused by various conditions, especially aging and overproduction of melanin in the epidermis or dermis of the skin. Iin addition to the application of topical lightening agents, different types of lasers, especially the Q-Switched ND:YAG laser, have been used for the treatment of cutaneous hyperpigmentation. Because of a high prevalence of idiopathic eye dark circles (EDCs) or periorbital melanosis and a poor response to available therapies, we decided to evaluate the efficacy and safety of the Fractional QS 1064 nm ND:YAG Laser through a before-after trial. Methods: 18-65-year-old patients with skin Fitzpatrick phototype of I-V and without any usage of a topical or systemic therapeutic regimen (2-4 weeks before the trial) were enrolled in the study. Each patient was treated with 6 sessions of the Fractional QS 1064 nm ND:YAG Laser at 2-week intervals and assessed for response and possible side effects or recurrences through 4 outcome measures, including Visoface-based color and erythema, melanin index and lightness (Before the fourth and sixth sessions of the therapy; also 1 week and 3 months after finishing the trial). Results: The changes of Visoface-based color and erythema, the melanin pigment amount by the Mexameter (melanin index) and the degree of lightness by the Colorimeter of patients after 6 months of intervention were statistically significant (P < 0.001). Conclusion: The fractional QS 1,064 nm ND:YAG Laser is an effective and safe therapy in EDCs since objective outcomes like the reduction of the melanin index and improving lightness and subjective ones like the reduction of darkness and erythema were confirmed.

Interaction of Long Time Pulses of an Nd3+:YAG Laser Beam with the Heusler AlloyNi45Co5Mn35.5In14.5.

In this paper, the laser processing of the surface of bulk and layered samples (of thickness 75 nm) of Ni45Co5Mn35.5In14.5 alloy (NC5MI) was investigated using microsecond laser pulses. A Q-switched pulsed Nd3+:YAG laser, operating in the 1st harmonic (which had a wavelength of 1064 nm) with a pulse duration of 250 µs, was used. NC5MI is a metal resistant to thermal laser processing because its reflection coefficient is close to unity for long wavelengths. The aim of this paper was to learn the forms of laser processing (heating, microprocessing, ablation) for which the above-specified type of laser is useful. The samples were irradiated with various fluences in the interval of 5–32 J·cm−2. The effect of the laser interaction with the surface was explored by SEM microscopy. The threshold fluences for the bulk sample were determined as: the visible damage threshold (Fthd = 2 ± 0.2 J·cm−2), the melting threshold (Fthm = 10 ± 0.5 J·cm−2), and the deep melting threshold (Fthdm = 32 J·cm−2). Unexpectedly, these values wereincreased for the layer sample due to its silicon substrate. We have concluded that this type of laser radiation is advantageous for the annealing and melting of, or drilling holes in, the alloy, but disadvantageousto the ablation of the alloy.

Synergistic Effect of 300 μm Needle-Depth Fractional Microneedling Radiofrequency on the Treatment of Senescence-Induced Aging Hyperpigmentation of the Skin

Aging-associated dermatological pigmentary diseases are associated with accumulation of senescence cells and the disruption of basement membrane due to chronic ultraviolet radiation (UVR) exposure. Our study is on the synergistic effect of the novel 300 μm needle-depth fractional microneedling radiofrequency (FMR) treatment and conventional Q-switched ND:YAG laser on aging-associated hyperpigmentation of the skin. The prospective controlled clinical trial of 25 Asian women revealed significantly higher improvements not only on wrinkles, but also on hyperpigmentation. Additional ex vivo study revealed significant reduction of pro-melanogenic markers as well as senescent keratinocytes, while increased expression of collagen type IV on the epidermal basement membrane, after additional FMR treatment on UV-irradiated human tissues. These results demonstrate that 300 μm needle-depth FMR might effectively remove senescent keratinocytes that secrete pro-melanogenic markers, and repair disrupted basement membrane, therefore preventing constant hyperpigmentation of the aged skin.

Diagnostics of zinc selenite plasma produced by FHG of a Q-switchedND: YAGlaser

We presented the OES studies of the Zinc Selenite ZnSe plasma produced by the FHG (1064nm) of a Q-switched ND: YAG laser. The target material was placed in front of laser beam in air at atmospheric pressure. the experimentally observed line profiles of zinc (ZnI) have been used to extract the Te using the Boltzmann plot method. Whereas, the ne has been determined from the Stark broadening method using the Zinc (Zn I) line. And it is calculated ωp, λd and Nd. The Te is calculated by varying the laser energy at (100, 200, 300, 400 and 500) mJ. It is observed that Te , ne and ωp increases as laser energy is increased while λd and Nd decreases as laser energy increased.

Efficacy and Safety of Topical Silymarin Versus Low Fluence 1064-nm Q Switched Nd:YAG Laser in the Treatment of Melasma: A Comparative Randomized Trial.

The management of melasma is challenging and requires multiple uses of available therapeutic options. To compare the short-term efficacy and safety of topical silymarin and low fluence 1064-nm Q-switched ND:YAG laser for treatment of melasma with dermoscopic follow-up. Fifty female patients with melasma were included in this study. They were randomly divided into two groups. Group A: 25 patients were treated with six sessions of low fluence Q switched ND:YAG 1064-nm laser, and group B: 25 patients were treated with topical silymarin cream 1.4% with a 3-monthtreatment duration. Patients were evaluated clinically by the modified melasma area and severity index (mMASI) score. Dermoscopic examinations were performed before and after the treatment sessions. The severity of melasma, as evaluated dermoscopically and clinically by mMASI score, was significantly reduced after treatment in all patients with no recorded side effects. There was no statistically significant difference between both studied groups regarding the change in mMASI score and dermoscopic assessment of the patients after the treatment sessions. Both low fluence Q switched ND:YAG 1064-nm laser and topical silymarin cream appear to be safe and effective modalities in the treatment of melasma. © 2021 Wiley Periodicals LLC.

Oral tranexamic acid, hydroquinone 4% and low-fluence 1064 nm Q-switched Nd:YAG laser for mixed melasma: Clinical and dermoscopic evaluation.

Tranexamic acid (TA) can prevent melanocyte activation by various stimuli. Combining TA with either hydroquinone 4% or Q-switched Nd:YAG laser may be associated with greater improvement of melasma. We aimed to evaluate the efficacy and safety of oral TA alone and combined with either topical hydroquinone 4% or low-fluence 1064nm Q-switched Nd:YAG laser in treatment of mixed melasma. Patients were randomly divided into three groups of 20 patients each. Group A were treated with oral TA 250mg twice daily for three months; group B were treated with TA similarly combined with topical hydroquinone 4% cream; group C were treated with TA combined with two sessions of 1064nm low-fluence Q-switched ND:YAG laser (850-1200mJ/cm2 , 4-5Hz,spot size 4mm) spaced 4weeks apart. Patients were followed monthly for 9months. After cessation of therapy, the mean mMASI score was lowest in group B (2.34±2.37) followed by groups A (6.38±4.04) and C (7.24±4.95).Mean percentage of mMASI score improvement was 35.91±24.13, 77.47±19.07, and 24.94±27.79 in groups A, B, and C (p<0.001). There was a significant reduction of telangiectasia in the three groups. Reported side effects were itching & irritation, post-inflammatory hyperpigmentation, and gastritis. Oral TA is a tolerable effective treatment modality for melasma. Combining hydroquinone 4% with oral TA is associated with a relatively earlier and better cosmetic outcome.

Comparison of carboxy therapy and fractional Q-switched ND:YAG laser on periorbital dark circles treatment: a clinical trial.

Treatment of the periorbital dark circles (PDCs) is a current challenge, with most treatment methods failing to yield promising results. The effectiveness of two common methods for periorbital dark circle treatment was compared in 28 patients with PDC. The patients were randomly divided into two groups of equal numbers: the first group received carboxy therapy, and the second group fractional 10,64 nm Q-switched Nd:YAG laser. In the carboxy therapy group, the treatment was performed six times, with 1-week intervals between sessions. In the group treated by Nd:YAG laser, the treatment was conducted in four sessions, with 1-month intervals between sessions. The results were evaluated through biometric evaluation, scoring on the visual analog scale (VAS) by both physicians and patients, and patients' satisfaction. Side effects of the treatments were also evaluated. The results showed that both carboxy therapy and Nd:YAG laser are effective in the treatment of periorbital dark circles, but carboxy therapy is significantly more effective. An increase in the skin lightness and a decrease in the melanin content of the periorbital skin was observed in the group receiving carboxy therapy, and these changes were more pronounced in this group compared to the group of Nd:YAG laser. In addition, side effects, such as erythema and post-inflammatory hyperpigmentation, were less in carboxy therapy than in Nd:YAG laser. Furthermore, the procedure was less expensive and easier to perform compared to Nd:YAG laser. Carboxy therapy is significantly more effective than Nd:YAG laser in PDC treatment.Trial registration: IRCT20080901001159N24.

Diode pumped Nd:YVO4/LBO/Ba(NO3)2 Raman laser at 563 nm

Radiation at a wavelength of 563 nm was achieved using an all-solid-state laser system based on a diode-pumped actively Q-switched Nd3+:YVO4 laser with intra-cavity second harmonic generation in LBO followed by intra-cavity Raman conversion in Ba(NO3)2. The output power of 101 mW was achieved under a pump power of 5 W and a modulation frequency of 12.7 kHz with a slope conversion efficiency of 19%. The achieved peak power at 563 nm was 0.67 kW, which allows one to use this laser in medical treatment through selective excitation of deoxyhemoglobin into its long-wavelength absorption peak.

High peak-power near-MW laser pulses by third harmonic generation at 355 nm in Ca5(BO3)3F nonlinear single crystals.

In this work, the performance of Ca5(BO3)3F (CBF) single crystals was investigated for the third harmonic generation at 355 nm. A high energy conversion efficiency of 16.9% at 355 nm was reached using a two-conversion-stage setup. First, using a high peak power, passively Q-switched Nd3+:YAG/Cr4+:YAG microlaser based gain aperture in micro-MOPA, the second harmonic at 532 nm was achieved with lithium triborate (LBO) crystal, reaching 1.35 MW peak power. On a second step, laser pulses at 355 nm were generated using a 5 mm-long CBF crystal growth by TSSG method with energy, pulse duration and peak power of 479 µJ, 568 ps and 0.843 MW, respectively. These results are currently the highest reported for CBF material.

Laser Skin Rejuvenation With Fractional 1064 Q-switched Nd:YAG In 252 Patients: An Indian Experience.

The objective of our study was to present the results and safety profile of fractional 1064 Q-switched Nd: YAG laser treatment in skin rejuvenation in Indian patients with Fitzpatrick skin type III-VI. We studied our clinical data of 252 patients who underwent treatment for facial skin rejuvenation with the Q switched Nd:YAG laser 1064 wavelength, using the fractional mode of 5mm spot size with fluences from 1.2J~2J/cm2 and the energy ranging from 300-500mJ, a repetition rate of 7Hz and pulse duration of 8 ns for 6 sessions at two weekly intervals. We evaluated results with the aid of clinical photography taken before start of treatment, on 3rd and 5th sessions along with patient satisfaction and dermatologist assessment scores. Any adverse events were also recorded. At the end of 6 sessions, both patients and dermatologists reported visible improvement in skin texture and tone. The laser sessions resulted in an immediate improvement in skin texture and tone in the first session itself that increased over 3 sessions and then stabilized. Transient erythema was reported in a few cases. No hypo- or hyperpigmentation were noted. The 1064 QSNYL is popularly used for skin rejuvenation especially in the Asian countries. But there is lack of substantial clinical data to validate the clinical results. We present the first study that shows the fractional 1064 Qswitched ND:YAG laser is a safe and effective option for skin rejuvenation in skin types III-VI.

Photomechanical effect of Q-switched ND:YAG laser enhance thrombolysis using of PLGA- based encapsulated tissue plasminogen activator (TPA) nanoparticles

Photomechanical effect of Q-switched ND:YAG laser enhance thrombolysis using of PLGA- based encapsulated tissue plasminogen activator (TPA) nanoparticles

Design and realization of a compact and multi-purpose passively Q-switched ND:YAG laser system

In this paper, a passively Q-switched pulsed Nd:YAG laser system is designed and realized for defense applications. Our previously published generalized mathematical model for passively Q-switched lasers is used to help extract the design parameters of the proposed Q-switched Nd:YAG laser system. The proposed laser system is a simple and compact laser source which can be employed for many applications. The laser system operates at 1064 nm, its free running output energy is 150 mJ, while its Q-switched laser output contains a train of pulses with pulse width varies from 47 nm to 85 nm and with maximum measured total output energy of 52.4 mJ. The output pulse series contains 6 pulses with maximum peak power of 468 kW, while the minimum obtained peak power is 18.8 kW. The total duration of the Q-switched output pulse series is about 150 μs. This system can be used in many applications such as Laser-induced breakdown spectroscopy (LIBS), LIDAR, laser target designation (LTD), range finding, and some medical applications.

High energy and stable polarized passively Q-switched Nd3+:YAG/V3+:YAG laser emission at 1444 nm and 722 nm

A QCW LD pumped linearly polarized Nd3+:YAG/V3+:YAG laser operating at 1444 nm with high peak power of 62 kW is demonstated for the first time. The polarization extinction ratio of the 1444 nm output beam was higher than 1000:1 and the highest second-harmonic generation efficiency at 722 nm was 62.8%. A compact high-peak-power polarized Nd:YAG laser can be used as the master oscillator for a high energy system. In particular, a 722 nm laser is a viable source for biomedical applications such as photoacoustic imaging, oximetry, and tattoo removal.

TiS2,MoS2,WS2/Sb2Te3 mixed nanosheets saturable absorber for dual-wavelength passively Q-switched Nd:GYSGG Laser

We demonstrate the mixed antimony telluride-molybdenum disulfide/tungsten disulfide/titanium disulfide as saturable absorber for efficient passively Q-switching of Nd:GYSGG laser. Sb2Te3-MoS2, Sb2Te3-WS2 and Sb2Te3-TiS2 dispersions with large populations of few layers were prepared by liquid-phase exfoliation. At the pump power of 5 W, dual-wavelength Q-switched operation were obtained with the output power of 0.46W, 0.42 W and 0.35W by using the mixed Sb2Te3-TiS2, Sb2Te3-WS2 and Sb2Te3-MoS2 SAs. The minimum pulse width was 254 ns with a pulse repetition rate of 72.4 kHz was obtained by using the Sb2Te3-MoS2 SA. Obviously, all the mixed saturable absorber shows better SA response. It also allows to generate laser pulse at two different wavelengths simultaneously.