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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • Titanium Dioxide Nanaoparticles
  • Hep-2 cell line
  • Mitotic Index
  • Q-switched pulsed Nd:YAG laser
  • Chromosomal Aberration
  • Blastogenic Index
应用领域
  • Applied Physics
机构单位
  • University of Technology (UOT)
  • Al-Farahidi University
  • Al-Nisour University Collage
  • Al-Rafidain University Collage
124 条数据
?? 中文（中国） ▾

  • Q-switched fiber laser based on CdS quantum dots as a saturable absorber

    摘要： In this work, a Q-switched fiber laser is demonstrated using quantum dots (QDs) cadmium sulfide (CdS) as a saturable absorber (SA) in an erbium-doped fiber laser (EDFL) system. The QD CdS is synthesized via the microwave hydrothermal assisted method and embedded into polyvinyl alcohol (PVA). The QD CdS/PVA matrix film is sandwiched in between two fiber ferrules by a fiber adapter. The generation of Q-switched fiber laser having a repetition rate, a pulse width, and a peak-to-peak pulse duration of 75.19 kHz, 1.27 μs, and 13.32 μs, respectively. The maximum output power of 3.82 mW and maximum pulse energy of 50.8 nJ are obtained at the maximum pump power of 145.9 mW. The proposed design may add to the alternative material of Q-switched fiber laser generation, which gives a high stability output performance by using quantum dots material as a saturable absorber.

    关键词： CdS Quantum Dots,erbium-doped fiber laser,microwave hydrothermal assisted method,saturable absorber,Q-switched fiber laser

    更新于2025-09-23 15:19:57

  • Zinc-oxide nanoparticle-based saturable absorber deposited by simple evaporation technique for Q-switched fiber laser

    摘要： A Q-switched erbium-doped fiber laser (EDFL) incorporating zinc-oxide (ZnO) nanoparticles-based saturable absorber (SA) is proposed and demonstrated. To form the SA, the ZnO nanoparticles, which are originally in the powder form, are first dissolved in ethanol and subsequently deposited onto the surface of fiber ferrule by using the adhesion effect with the evaporation technique. By integrating the ZnO nanoparticle-based SA into a laser cavity of an EDFL, a self-started and stable Q-switching is achieved at a low threshold power of 20.24 mW. As the pump power is increased, the pulse repetition rate is tunable from 10.34 kHz to 25.59 kHz while pulse duration decreases from 21.39 μs to 3.65 μs. Additionally, this Q-switched laser has a maximum energy per pulse of 19.34 nJ and an average output power of 0.46 mW. These results indicate the feasibility and functionality of the ZnO nanoparticles-based SA for Q-switched generation, which offers the flexibility and easy integration of the SA into a ring laser cavity.

    关键词： saturable absorber,zinc oxide,fiber laser,Q-switched

    更新于2025-09-23 15:19:57

  • [IEEE 2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE) - Cochin, India (2020.1.2-2020.1.4)] 2020 IEEE International Conference on Power Electronics, Smart Grid and Renewable Energy (PESGRE2020) - Maximum Power Point Tracking for Photovoltaic-Fed Multi-Source Switched Capacitor Based Multilevel Inverter

    摘要： In this paper, a shifting carrier based maximum power point tracking (MPPT) algorithm for multisource converters is proposed. This MPPT algorithm is explained for both low frequency (constant carrier) and high frequency (triangular) carrier signals. The proposed algorithm is applied for a single stage multisource switched capacitor based multilevel inverter for grid connected and stand-alone photovoltaic applications. This converter features high gain, less component count, self capacitor charge balancing, better dispersed value of sources and increased source utilization. The importance of selecting an appropriate pulse width modulation technique for switched capacitor based inverters in order to maintain the capacitor charging time is explained. The proposed technique is able to track the maximum power under varying irradiance levels. The experimental results of the proposed algorithm is presented. The MPPT technique is analyzed and veri?ed in simulation for stand-alone and grid connected applications using MATLAB/Simulink platform.

    关键词： multilevel inverter,Switched capacitor based converter,maximum power point tracking

    更新于2025-09-23 15:19:57

  • 188a??ns pulsed Ho:Sc2SiO5 laser operating at 2107.2a??m employing a few-layer graphene saturable absorber

    摘要： A passively Q-switched Ho:Sc2SiO5 laser operating at 2107.2 nm with a few layered graphene saturable absorber is obtained, corresponding to a beam quality factors of =1.21 .A maximum average output power of 1.37 W and pulse energy of 16.08 μJ was achieved at an incident pump power of 13.2 W. The shortest pulse width of 188.3 ns and maximum pulse repetition rate of 85.26 kHz were observed, with a maximum peak power of 85.4 W.

    关键词： Ho:Sc2SiO5(SSO) crystal,2 μm,Passive Q-switched,Graphene

    更新于2025-09-23 15:19:57

  • Doubly Q-switched single longitudinal mode Nd:YAG laser with electro-optical modulator and Cr4???:YAG

    摘要： An electro-optical modulator (EOM) and Cr4+:YAG saturable-absorber-based doubly Q-switched Nd:YAG laser at 1.06 μm with single-longitudinal-mode (SLM) output was demonstrated. The spatial-hole-burning suppression and cavity axial-mode selection were provided by a twisted-mode technique and resonant-reflector-mediated SLM operation. The Cr4+:YAG initial transmittance (??0) affected the pulse profile, pulse energy, and laser spectra, which were analyzed theoretically and experimentally. Consequently, the laser output obtained an SLM rate of 96.2% with a symmetry factor of 0.64 when ??0 was 6.2%. The results indicate that symmetric and SLM laser pulse can be obtained in a double Q-switched laser by adjusting the cavity loss according to ??0. Compared with a solely Q-switched laser, the double Q-switches of EOM and Cr4+:YAG provide a practical route toward the generation of a symmetric temporal profile and SLM operation.

    关键词： Twisted-mode cavity,Symmetric pulses,Doubly Q-switched,Resonant reflector,Single-longitudinal-mode

    更新于2025-09-23 15:19:57

  • Epsilon-near-zero medium for optical switches in Ho solid-state laser at 2.06????m

    摘要： Indium tin oxide (ITO), an epsilon-near-zero material in the low-dimensional family, was successfully fabricated and first used as an optical switcher in 2.06 μm. In the Tm:fiber pumped passively Q-switched laser, a maximum average output power of 312 mW was obtained with a shortest pulse width of 2.42 μs and a repetition rate of 20.53 kHz, corresponding to a single pulse energy and a peak power of 15.20 μJ and 6.28 W, respectively. Results suggest that ITO is looking forward to develop into a kind of suitable saturable absorber for generation of nanosecond pulse in solid state lasers.

    关键词： Passively Q-switched,Optical switch,Indium tin oxide,Epsilon-near-zero,2.06 μm

    更新于2025-09-23 15:19:57

  • High peak power, high-repetition rate passively Q-switching of a holmium ceramic laser

    摘要： We demonstrated a high peak power, high repetition rate Cr2+:ZnS passively Q-switched (PQS) Ho:YAG ceramic laser. Particularly, the influence of the initial transmission of the saturable absorber (SA) on the laser performance was investigated with two kinds of SAs. Finally, the laser generated average output power of 10.3 W and the stable 13.3 ns, 1.02 mJ pulses were achieved at a 10.1 kHz repetition rate. In addition, the highest peak power of 75.9 kW was obtained, to our best knowledge, which was also the highest peak power achieved in a ~2 μm PQS ceramic laser, corresponding to the intra-cavity peak power of 0.23 MW.

    关键词： passively Q-switched (PQS),ceramic materials,high-peak power

    更新于2025-09-23 15:19:57

  • [IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Injection Dependent Lifetime Spectroscopy for Two-Level Defects in Silicon

    摘要： In this letter, a new single-anchor indoor localization concept employing electronically steerable parasitic array radiator (ESPAR) antenna has been proposed. The new concept uses a simple ?ngerprinting algorithm adopted to work with directional main beam and narrow minimum radiation patterns of ESPAR antenna that scans 360 area around the base station, while the signal strength received from a mobile terminal is being recorded for each con?guration. The letter describes the antenna design and necessary ?ngerprinting algorithm expansion and shows measurements of the proof-of-concept prototype performed within the experimental setup. Localization results obtained from indoor measurements indicate that the proposed concept can provide better results than the similar approach based on a switched-beam antenna introduced by Giorgetti et al. (IEEE Commun. Lett., vol. 13, no. 1, pp. 58–60, Jan. 2009).

    关键词： switched-beam antenna,Electronically steerable parasitic array radiator (ESPAR) antenna,indoor localization,?ngerprinting,smart antenna,wireless positioning system

    更新于2025-09-23 15:19:57

  • [IEEE 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - Santos, Brazil (2019.12.1-2019.12.4)] 2019 IEEE 15th Brazilian Power Electronics Conference and 5th IEEE Southern Power Electronics Conference (COBEP/SPEC) - A Resonant-Switched-Capacitor Step-Down DCa??DC Converter in CCM Operation as an LED Driver

    摘要： This paper proposes a analysis of a LED driver. The driver consists of a resonant switched capacitor converter designed to operate in CCM and fed from nanogrid. This mode of operation allows the reduction of current peaks and, consequently, reduction of conduction losses. There is ZVS in the turn-off of the switches due to the full charge and discharge of the switched capacitor. Therefore, switching losses are also reduced. The inductor operates at twice the switching frequency, contributing to the reduction of the magnetic elements. In addition, this converter has the advantage of stabilizing the power of the LED by adjusting the switching frequency, without the needing sensors and control circuit, which reduces the cost of the circuit. In order to validate the comparative analysis, a 10W prototype was designed in a laboratory, operating with a switching frequency of approximately 58 KHz, and presenting an overall ef?ciency of 92.8% in nominal conditions.

    关键词： CCM,LED Driver,Resonant Switched Capacitor (RSC) Converter,ZVS

    更新于2025-09-23 15:19:57

  • Q-switched all-fiber laser based on MoSe <sub/>2</sub> films with chemical vapor deposition method

    摘要： In this work, MoSe2 ˉlm is synthesized by the chemical vapor deposition method. Saturable absorber (SA) is assembled with the tapered ˉber and MoSe2 ˉlms. Q-switched operation is achieved with the MoSe2-based SA. The experimental result reveals that the MoSe2-based SA has excellent saturable absorption characteristic with 23.41% modulation depth. When the pump power is greater than 289.2 mW, Q-switched all-ˉber lasing action is demonstrated. The repetition rate of the Q-switched pulses varies from 185.6 to 252.8 kHz. The shortest pulse duration is 801.9 ns, and the largest output energy is 69.3 nJ. Results indicate that MoSe2 ˉlms can provide new opportunities for large-modulation-depth optical modulators in ultrafast photonics.

    关键词： Q-switched,saturable absorbers,ˉber laser,Nonlinear optical materials

    更新于2025-09-23 15:19:57