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- 2019
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- Q-switched pulsed Nd:YAG laser
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- University of Technology (UOT)
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Q-Switched and Mode-Locked Nd/Cr:YAG Ceramic Pulse Laser
摘要： A mode-locked and Q-switched short pulse laser using the Nd3+/Cr3+:YAG ceramic has been constructed with a SESAM and Cr4+:YAG crystal optical switch based on excite state absorption (ESA). Laser oscillations of the pulse laser were observed experimentally. The Nd/Cr:YAG ceramic laser has a high conversion e?ciency from white light (such as lamp light or solar light) to the laser. The Nd/Cr:YAG ceramic has a higher laser gain than the Nd:YAG laser for the same pumping power. The laser oscillation can be obtained very easily. A single-mode-locked laser pulse with fast modulation on the order of 100 ps was obtained in some pump power regimes when using the Cr4+:YAG crystal. The obtained pulse duration of the short pulse was a few hundred ps. A maximum peak power of 60 kW was obtained when using a SESAM. The same level of peak power (60 kW) was also obtained when using the Cr4+:YAG crystal.
关键词： Q-switched,Nd/Cr:YAG ceramic,mode-locked,pulse laser,Cr4+:YAG crystal,SESAM
更新于2025-09-23 15:19:57
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Tattoo??removal a??the artistic state of the art.a?? Tattoo on forehead, nose, and chin: Successful removal with modified R20 technique using low-fluence Q-switched Nd YAG laser: A case report
摘要： Background: Tattooing is an ancient practice that has been performed all over the world which is used to beautify the skin and augment beauty. Regrettable tattoos are treated with Q switch lasers, in many sessions, and the effectiveness is doubtful. Objectives: The aim of this paper is to demonstrate how a unique protocol of R20 Q switch Nd YAG laser, can be employed successfully in removing long standing facial tattoos, in skin type IV, in an effective disciplined timing and cost wise modalities. The adopted method was a-4 single passes, with 20 minutes gap respectively. Methods and Results: A lady received the conventional Q switch laser at one session, with no noticeable results. On the other session, she received the R20 method, and an immediate whitening reaction was observed. No adverse reactions were noted. Conclusion: The R20 Q technique is very effective tool in a single treatment session than the conventional multiple laser sessions, in tattoo removal, and I would invite other dermatologists utilize it in their clinical setting. This method does not need any newer laser technology, clears the tattoo fast, and cuts down unnecessary treatment duration and cost.
关键词： Q switched Nd YAG laser,R20,laser tattoo removal
更新于2025-09-23 15:19:57
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Switched Capacitor-Coupled Inductor DCa??DC Converter for Grid-Connected PV System using LFCSO-Based Adaptive Neuro-Fuzzy Inference System
摘要： In this paper, the Levy °ight-based chicken swarm optimization (LFCSO) is proposed to follow the highest power of grid-joined photovoltaic (PV) framework. To analyze the grid-associated PV framework, the characteristics of current, power, voltage, and irradiance are determined. Because of the low yield voltage of the source PV, a big advance up converter with big productivity is required when the source PV is associated with the matrix power. A tale great advance up converter dependent on the exchanged capacitor and inductor is illustrated in this paper. The LFCSO algorithm with the adaptive neuro-fuzzy inference system is used to generate the control pulses of the transformer-coupled inductor DC–DC converter-less switched capacitor. While using the switched capacitor-coupled inductor, the voltage addition is expanded in the DC–DC converter and the power of PV is maximized. Here, the normal CSO algorithm is updated with the help of Levy °ight functions to generate optimal results. To get the accurate optimal results, the output of the proposed LFCSO algorithm is given as the input of the ANFIS technique. After that, the optimal results are generated and they provide the pulses for the system. The working guideline is analyzed and the voltage addition is derived with the utilization of the proposed technique. From that point forward, it predicts the exact maximum power of the converter according to its inputs. Under the variety of solar irradiance and partial shading conditions (PSCs), the PV system is tested and its characteristics are analyzed in di?erent time instants. The proposed LFCSO with ANFIS method is actualized in Simulink/MATLABstage, and the tracking executing is examined with a traditional method such as genetic algorithm (GA), perturb and observe (P&O) technique–neuro-fuzzy controller (NFC) and fuzzy logic controller (FLC) technique.
关键词： irradiance,Levy °ight-based chicken swarm optimization algorithm,partial shading conditions,transformer-less switched capacitor-coupled inductor DC–DC converter voltage,current,power,grid-connected PV,GA-NFC and FLC methods
更新于2025-09-23 15:19:57
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Semiconducting Polymer Dots as Broadband Saturable Absorbers for Q-switched Fiber Lasers
摘要： Semiconducting polymer dots (Pdots) have attracted much attention due to their outstanding optical properties. However, Pdots potential in laser technology is rare. Here, we first report the benzobisthiadiazole (BBT)-based Pdot as a single broadband nonlinear saturable absorber (SA) for passively Q-switched fiber lasers at 1, 1.5, and 2 μm. The Pdots-SA possesses a strong saturable absorption, broadband nonlinear optical response, and large modulation depth. Once the Pdots-SA is integrated into the ytterbium-, erbium-, and thulium-doped fiber laser cavities, stable Q-switched operations are observed at the central wavelengths of 1036, 1561, and 1951 nm. Our results verify that the Pdots are promising nonlinear media for Q-switched pulses generation, and highlight the potential of Pdots for relevant nonlinear optical applications.
关键词： Saturable absorber,Semiconducting polymer dots,Q-switched fiber lasers,Broadband nonlinear optical response
更新于2025-09-23 15:19:57
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Tungsten tri-oxide (WO <sub/>3</sub> ) film absorber for generating Q-switched pulses in erbium laser
摘要： This paper reports a new type of passive saturable absorber (SA) made of transition metal oxide (TMO) embedded in polyvinyl alcohol (PVA). The Tungsten trioxide (WO3)-PVA SA is placed in an erbium-doped fibre laser cavity to produce Q-switched pulses operating at 1562.82 nm. The pulse laser starts to manifest at the threshold pump power of 40 mW and continues to exist until the maximum pump power of 195 mW. Within that pump power range, its pulse energy, repetition rate and pulse width vary from 98 to 142.85 nJ, 29.86 to 56.7 kHz and 5.032 to 1.85 μs, respectively. The pulse train is stable with a signal to noise ratio of 70 dB. This is the first demonstration of a Q-switched laser using such a SA.
关键词： saturable absorber,WO3,Q-switched,Erbium-doped fibre laser
更新于2025-09-23 15:19:57
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Experimental observation of bound states of Q-switched fiber lasers mode-locked by carbon nanotubes
摘要： We demonstrate the experimental observation of bound states of Q-switched lasers mode-locked by carbon nanotubes. When bound states of Q-switched mode-locked lasers are formed, the Fourier transformation results into multiwavelength spectrum due to the small temporal interval induced by polarization controller. We find that the wavelength spacing is highly sensitive to pump power. A wavelength spacing tuning from ~0.057 nm to 1.569 nm with a pump power variation less than 4 mW is obtained. The wavelength spacing is also highly sensitive to the nonlinear phase induced by polarization controller. These findings enrich our understanding about the complex dynamics of the Q-switched mode-locked lasers.
关键词： carbon nanotubes,bound states,mode-locked,nonlinear phase,Q-switched fiber lasers
更新于2025-09-23 15:19:57
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[IEEE 2019 International Aegean Conference on Electrical Machines and Power Electronics (ACEMP) & 2019 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM) - Istanbul, Turkey (2019.8.27-2019.8.29)] 2019 International Aegean Conference on Electrical Machines and Power Electronics (ACEMP) & 2019 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM) - Identifying Internal Defects of Photovoltaic Panels Using Sweep Frequency Response Analysis
摘要： In this paper, we propose a discrete-time IIR low-pass ?lter that achieves a high-order of ?ltering through a charge-sharing rotation. Its sampling rate is then multiplied through pipelining. The ?rst stage of the ?lter can operate in either a voltage-sampling or charge-sampling mode. It uses switches, capacitors and a simple gm-cell, rather than opamps, thus being compatible with digital nanoscale technology. In the voltage-sampling mode, the gm-cell is bypassed so the ?lter is fully passive. A 7th-order ?lter prototype operating at 800 MS/s sampling rate is implemented in TSMC 65 nm CMOS. Bandwidth of this ?lter is programmable between 400 kHz to 30 MHz with 100 dB maximum stop-band rejection. Its IIP3 is +21 dBm and the averaged spot noise is 4.57 nV/ Hz. It consumes 2 mW at 1.2 V and occupies 0.42 mm2.
关键词： switched capacitor,low power,high linearity,IIR,low-pass ?lter,low noise,recon?gurable,high order,real pole,discrete time,digital equalization,passive,CMOS
更新于2025-09-23 15:19:57
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Threshold decrease and output-power improvement in dual-loss Q-switched laser based on few-layer WTe<sub>2</sub> saturable absorber
摘要： A dual-loss Q-switched laser was realized by applying a home-made 2.5 nm-thick WTe2 to an acoustic-optic (AO) modulated laser. Besides conventional pulse compression, the participation of WTe2 could obviously improve the average output power by 29.6% and reduce the laser threshold by 20%, even with the introduced 8% nonsaturable loss. The average-output-power improvement and pulse compression in this dual-loss modulated laser resulted in a 113.7% increase of peak power. According to the measured spectra of laser and photoluminescence of WTe2, the laser-induced excitonic light-emission may be the reason of this laser gain.
关键词： WTe2 saturable absorber,laser threshold decrease,pulse compression,output-power improvement,dual-loss Q-switched laser
更新于2025-09-23 15:19:57
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Passively Q-switched Tm:YAlO3 laser based on WS2/MoS2 two-dimensional nanosheets at 2????m
摘要： A comparison of the pulsed laser performances of 2 μm passively Q-switched Tm:YAlO3 (YAP) lasers based on the use of tungsten disul?de (WS2) and molybdenum disul?de (MoS2) two-dimensional (2D) nanosheets as saturable absorbers is reported. The novel nanosheets were prepared by chemical vapor deposition (CVD) technology. The microstructure and optical characteristics of the nanosheets were investigated experimentally. In a continuous-wave (CW) operation, the maximum output power of 2.8 W was obtained at an absorbed pump power of 6.9 W, with a corresponding slope e?ciency of 46.4%. In a passively Q-switched operation at a pump power of 1.45 W, the average output power, pulse width, repetition rate, pulse energy, and peak power for the Tm:YAP/WS2 laser were 0.11 W, 2.65 μs, 34.7 kHz, 2.9 μJ, and 1.23 W, respectively. As for the Tm:YAP/MoS2 laser, the corresponding values were 0.10 W, 2.5 μs, 24.0 kHz, 3.8 μJ, and 1.55 W.
关键词： WS2/MoS2 nanosheets,Passively Q-switched,Chemical vapor deposition,Tm:YAlO3 laser,2 μm
更新于2025-09-23 15:19:57
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Promotion impact of thermal oxidation etching to saturable absorption performance of g-C3N4
摘要： A facile thermal modification method based on thermal oxidation etching was successfully developed as an effective way of improving the photoelectric properties of graphite carbon nitride (g-C3N4), and the as-prepared modified g-C3N4 was employed as the saturable absorber (SA) for a passively Q-switched Nd:LLF laser at 1.06 μm to improve the laser performance. Under the incident pump power of 7.68 W, a pulsed laser output with 110 ns pulse width at 95.5 kHz pulse repetition rate was achieved, which was the narrowest among the g-C3N4 materials used as SAs around 1 μm.
关键词： Q-switched laser,2D materials,g-C3N4 saturable absorber,Infrared lasers
更新于2025-09-19 17:15:36