- 标题
- 摘要
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- 实验方案
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Passively Q-switched and mode-locked Tm-Ho co-doped fiber laser using a WS2 saturable absorber fabricated by chemical vapor deposition
摘要： We demonstrate a passively Q-switched and mode-locked Tm-Ho co-doped fiber laser based on a WS2 saturable absorber (SA) fabricated by chemical vapor deposition method. When the pump power increases from 0.32 W to 0.38 W, the repetition rate of the Q-switched laser pulse increases 47.1 kHz to 90.1 kHz and the pulse width decreases from 6.2 μs to 1.7 μs. In addition, the mode-locking operation can also be observed by adjusting the polarization controller (PC) and mode-locked laser pulses at 1883.2 nm can be achieved at a high pump power between 0.5 W and 0.64 W. The pulse duration is 1.07 ns and repetition rate is 23.8 MHz and the pulse is the longest mode-locked pulse with WS2-SA ever reported.
关键词： Mode-locked lasers,Optical fiber lasers,Ultrafast optics
更新于2025-11-28 14:24:03
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Alternated Q-switched and gain-switched dual-pulse Yb fiber laser with Tm-Ho co-doped fiber as saturable absorber
摘要： We demonstrate a dual-wavelength and dual-pulse Yb-doped fiber laser with a Tm-Ho co-doped fiber as saturable absorber (SA). The wavelength of the first pulse in the dual-pulsing output is at 1064 nm generated via SA-induced self Q-switching and the second pulse is at 2127.7 nm and generated by gain-switching with the laser at 1064 nm as the pump for the Tm ions in the Tm-Ho co-doped fiber and thus induced stimulated emission. With the increases of the pump power, the pulse duration of the two pulses is decreased depending on the level of the pump. The pulse duration of the laser at 1064 nm decreases from 1.4 μs to 296 ns when the pump power increases from 275 mW to 475 mW, while the pulse duration at 2127.7 nm is reduced from 440 ns to 246 ns when the pump increases from 300 mW to 475 mW. Accordingly, the repetition rate is decreased from 17.4 kHz to 6.8 kHz. The experimental result shows that Tm-Ho co-doped fiber is an excellent candidate for SA-induced Q-switching at 1064 nm.
关键词： Q-switched lasers,Optical fiber lasers,Ultrafast optics
更新于2025-11-28 14:24:03
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Tunable Ytterbium-Doped Mode-locked Fiber Laser Based on Single-Walled Carbon Nanotubes
摘要： A tunable mode-locked ytterbium-doped fiber laser with a tuning range of 55 nm is demonstrated. Currently, this is the widest tuning range for all-normal dispersion (ANDi) ytterbium-doped mode-locked fiber laser based on new-material saturable absorber (SA). The combined effects of the single-walled carbon nanotubes (SWCNTs) saturable absorber and a reflective grating significantly improved laser performance: broad tuning range, superb stability and repeatability. The experimental results indicate that SWCNTs can be a brilliant saturable absorber in all-normal dispersion regime at 1 μm, with pulse width of 2.4 ps and optical spectral bandwidth of 1.6 nm across the full tuning range. The laser also shows that the optical spectrum can be tuned accurately and continuously, which gives possibility for various applications such as optical communications, spectroscopy, time-resolved measurement, etc.
关键词： optical tuning,mode locked,fiber laser,Ultrafast optics,carbon nanotubes
更新于2025-11-28 14:24:03
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Application of the Hollow Core Fiber Ended with Fiber Microlens in the Multiphoton Excitation Setup
摘要： In this paper an ultrathin lensed fiber-optics probe for multiphoton fluorescence endoscopy is presented. The probe is made by attaching a segment of multimode (MM) fiber to the distal end of the hollow core, photonic bandgap fiber (HCPBF) and generating a curved surface at the tip of the MM fiber using a fiber arc fusion splicer the electric arc of a fusion splicer. The curved surface served as a micro fiber-optic lens and focused the exiting light beam. It simultaneously protected the HCF tip against contamination.
关键词： fiber microlens,ultrafast optics,photonic crystal fibers
更新于2025-09-23 15:22:29
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Second harmonic generation at 544a??nm of a femtosecond laser
摘要： We study second harmonic generation (SHG) at 544 nm of the 0-type (e + e - e) quasi-phase-matching based on a femtosecond laser at 1088 nm. The green pulse with the spectrum width of 0.6 nm and the peak power of 17.7 kW is obtained at the pump power density of 2.81 GW/cm2 and the conversion e?ciency is 21 %. As the propagation distance along the PPMgLN crystal increases, the spectrum at 544 nm becomes narrower and narrower and the pulse duration broadens very seriously.
关键词： Group velocity match,544 nm laser,Second harmonic generation,PPMgLN,Ultrafast optics,Femtosecond pulses
更新于2025-09-23 15:21:01
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Sub-nanosecond multiple-wavelength harmonic mode-locked Tm-Ho co-doped fiber laser
摘要： We demonstrate an all-fiber sub-nanosecond passively mode-locked Tm-Ho co-doped fiber laser. With 1.1-km single-mode fiber (SMF) inserted into the cavity, the laser system can generate 183.4-kHz and 720-ps pulses based on a GaAs saturable absorber (SA). The output spectrum is presented with three wavelengths, which are at 1858.5, 1861.3, and 1864.2 nm, respectively. In addition, with the adjustment of the polarization controller and pump power, the multiple-pulse operation, such as the harmonic mode-locking operation, can also be observed. Higher order of harmonic mode locking is promising but limited by the damage threshold of the SA.
关键词： Mode-locked lasers,Ultrafast optics,Optical fiber lasers
更新于2025-09-23 15:21:01
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Multi-octave spanning, Watt-level ultrafast mid-infrared source
摘要： We present a source of brilliant mid-infrared radiation, seamlessly covering the wavelength range between 1.33 and 18 μm (7500–555 cm?1) with three channels, employing broadband nonlinear conversion processes driven by the output of a thulium-fiber laser system. The high-average-power femtosecond frontend delivers a 50 MHz train of 250 fs pulses spectrally centered at 1.96 μm. The three parallel channels employ soliton self-compression in a fused-silica fiber, supercontinuum generation in a ZBLAN fiber, and difference-frequency generation in GaSe driven by soliton self-compressed pulses. The total output enables spectral coverage from 1.33 to 2.4 μm, from 2.4 to 5.2 μm, and from 5.2 to 18 μm with 4.5 W, 0.22 W and 0.5 W, respectively. This spatially coherent source with a footprint of less than 4 m2 exceeds the brilliance of 3rd-generation synchrotrons by more than three orders of magnitude over 90% of the bandwidth.
关键词： intra-pulse difference frequency generation (DFG),ultrafast optics,supercontinuum generation,mid-infrared generation,ZBLAN optical fibre,nonlinear optics
更新于2025-09-23 15:19:57
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Broadband ultrafast nonlinear optical studies revealing exciting multi-photon absorption coefficients in phase pure zero-dimensional Cs <sub/>4</sub> PbBr <sub/>6</sub> perovskite films
摘要： Lead halide perovskite nanocrystals (NCs) apart from their overwhelming optoelectronic applications have recently demonstrated promising nonlinear optical (NLO) properties such as strong two-photon absorption cross-sections (～105 GM), two-photon fluorescence, and saturable absorption even at very high peak intensity. Zero-dimensional perovskite-related materials (0-D PRMs) are a new class of materials offering a high exciton binding energy (Eg ≥ 180 meV) with a strong photoluminescence (PL) quantum yield in few cases. Herein, we report the broadband third-order NLO properties of phase pure Cs4PbBr6 0-D PRM achieved using the Z-scan and degenerate four-wave mixing techniques in the femtosecond regime. Considering the growing content of the fluorescent and non-fluorescent forms of this material, we have performed our studies on both of them. These perovskite NCs exhibited strong multi-photon absorption properties in the near-infrared region with two-photon absorption (2PA) (cross-section, σ2 = 10?43–10?44 cm4 s equivalent to ～106 GM) in the 500–800 nm region, three-photon absorption (3PA) (cross-section, σ3 ～10?73 cm6 s2) in the 900–1200 nm region and four-photon absorption (4PA) (cross-section, σ4 ～10?100 cm8 s3) in the 1300–1500 nm spectral region. These multi-photon absorption processes are explained using a simple band diagram. The measured NLO coefficients and cross-sections are fairly large when compared to some of the earlier reports on perovskite-based NCs. Cs4PbBr6 0-D PRM also demonstrated a large third-order NLO susceptibility χ(3) (～10?7 esu), which can be attributed to the strong quantum confinement arising from spatially isolated, exciton containing individual [PbBr6]4? octahedron. These results clearly suggest the potential of 0D-PRMs in applications such as photonics and ultrafast all-optical switching devices.
关键词： Z-scan,perovskite nanocrystals,ultrafast optics,degenerate four-wave mixing,multi-photon absorption,nonlinear optical properties
更新于2025-09-19 17:15:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Controlling the Near-Field of Metasurfaces for Free-Electron Multi-Harmonic Hard X-Ray Generation
摘要： Metasurfaces are subwavelength spatial variations in geometry and material, and offer us an ingenious way of manipulating far-field radiation. Here, we show that their ability to manipulate the near-field is also an extremely powerful lever in controlling nanophotonic photon-electron interactions. The metasurface near-field contains high-order spatial harmonics that can be leveraged to generate substantial high harmonic components, whose properties are directly tunable through the metasurface geometry, the electron energy and the incidence angle of the input laser. By developing an analytical theory that produces results in excellent agreement with our ab initio simulations, we show how the design of metasurface-enhanced plasmons can be leveraged to produce intense and highly-directional multi-harmonic emission in the X-ray and the gamma-ray range. Furthermore, we show that the use of few-cycle laser pulses is instrumental in enhancing the intensity and bandwidth of the radiation output while avoiding damage to the metasurface. As an example, we present the design of a four-color X-ray source.
关键词： X-rays,sources,ultrafast optics,plasmonics,metasurface
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Low-voltage light beam steering by planar dual-domain nematic liquid crystal deflector
摘要： We present photoemission time-delay measurements between electrons originating from the valence shells of neon and argon obtained by attosecond streaking. After giving a brief review of the different techniques, we focus on more detailed analysis using the attosecond streaking technique. We show that the temporal structure of the ionizing single attosecond pulse may significantly affect the obtained time delays, and we propose a procedure how to take this contribution properly into account. Our analysis reveals a delay of a few tens of attoseconds in a photon energy range between 28 and 40 eV in the emission of electrons ionized from argon with respect to those liberated from neon.
关键词： Atomic physics,ultrafast optics,time measurement,ultraviolet spectroscopy
更新于2025-09-19 17:13:59