共查询到20条相似文献,搜索用时 15 毫秒
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When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As2S3 fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As2S3 material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system. 相似文献
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Double-clad Tm3+-doped silica fiber laser with Bragg grating inscribed directly into active core by femtosecond laser 总被引:1,自引:0,他引:1
C. W. Song Y. J. Zhang B. Q. Yao Y. Wang W. Wang Y. L. Ju Y. Z. Wang 《Laser Physics》2009,19(5):1009-1012
We report for the first time to inscribe the Fiber Bragg Grating (FBG) in Tm3+-doped multimode double-clad silica fiber by 800 nm femtosecond laser with a phase mask. The 1.35 μm period Bragg grating is written into the fiber core, which is responded to the laser center wavelength located at nearly 1960 nm. Continuous wave total output power of 11.5 W is obtained under the launched pump power of 29.8 W, corresponding to a slope efficiency of 45.0% and a conversion efficiency of 38.6%. 相似文献
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This work focuses on the effects of different ultrasound power densities on the microstructural changes and physicochemical properties of okara fibers, which are composed of carbohydrate-based polymers. Okara suspensions were treated with ultrasound at different power densities (0, 1, 2, 3, 4, and 5 W/mL) for 30 min, after which the ultrasound-treated okara were hydrolyzed by trypsin to obtain okara fibers. The ultrasound treatment of the okara fibers induced structural disorganization and changes, evidenced mainly in their morphological characteristics and their relative crystallinity degrees. Increasing the ultrasound power broke the okara fibers into flaky and stacked structures. When the ultrasound power density reached 4 W/mL, the parenchyma became compact and the hourglass structure fractured. The mean particle size of the okara fiber was reduced from 82.24 µm to 53.96 µm, and the homogeneity was enhanced significantly. The relative crystallinity of the okara fibers was reduced from 55.14% to 36.47%. The okara fiber surface charge decreased when the ultrasound power was increased. However, after ultrasound treatment at 4 W/mL (800 W), the okara fiber suspension exhibited the highest viscosity value and a higher swelling capacity, water-holding capacity, and oil-holding capacity. Therefore, the results indicated that the selection of processing conditions for okara fibers is critical and that okara fiber modification using a high ultrasound treatment might improve their use in potential applications. 相似文献
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Zaouter Y Martial I Aubry N Didierjean J Hönninger C Mottay E Druon F Georges P Balembois F 《Optics letters》2011,36(5):748-750
We demonstrated that Yb:YAG single crystal fibers have a strong potential for the amplification of femtosecond pulses. Seeded by 230?fs pulses with an average power of 400?mW at 30?MHz delivered by a passively mode-locked Yb:KYW oscillator, the system produced 330?fs pulses with an average power of 12?W. This is the shortest pulse duration ever produced by an Yb:YAG amplifier. The gain in the single crystal fiber reached a value as high as 30 in a simple double-pass configuration. 相似文献
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We demonstrate fiber distributed feedback (DFB) lasers using Raman gain in two germanosilicate fibers. Our DFB cavities were 124 mm uniform fiber Bragg gratings with a π phase shift offset from the grating center. Our pump was at 1480 nm and the DFB lasers operated on a single longitudinal mode near 1584 nm. In a commercial Raman gain fiber, the maximum output power, linewidth, and threshold were 150 mW, 7.5 MHz, and 39 W, respectively. In a commercial highly nonlinear fiber, these figures improved to 350 mW, 4 MHz, and 4.3 W, respectively. In both lasers, more than 75% of pump power was transmitted, allowing for the possibility of substantial amplification in subsequent Raman gain fiber. 相似文献
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T. Eidam F. Röser O. Schmidt J. Limpert A. Tünnermann 《Applied physics. B, Lasers and optics》2008,92(1):9-12
We report on the generation of 27 fs pulses with an average output power of 57 W and a repetition rate of 78 MHz. The pulses
are generated by combining a high average power fiber chirped pulse amplification (FCPA) system with a microstructured large-mode-area
fiber for nonlinear compression. The FCPA system delivers 270 fs pulses in a linearly polarized beam with diffraction-limited
quality. Nonlinear compression is achieved by launching the pulses into a short (few cm) piece of microstructured fiber and
subsequent compression by a pair of chirped mirrors.
PACS 42.55.Wd; 42.55.Xi, 42.65.Re 相似文献
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Using 1064 nm CW Nd:YVO4 solid-state laser as a pump, 1-km phosphosilicate fiber and cascaded cavities with two pairs of fiber Bragg grating mirrors for 1239 and 1484 nm, we obtained a CW 800 mW/1484 nm Raman fiber laser (RFL) for an actual incident pump power of about 2 W (Nd:YVO4 power of 6.90 W). The conversion efficiency is as high as 40%. To the best of our knowledge, this is the highest conversion efficiency of RFL pumped by solid-state laser. The output power instability at 1484 nm in half an hour is less than 3%. In addition, the numerical simulations are also performed. Good agreement between the results of numerical simulation and the results of the experiment has been demonstrated. 相似文献
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使用FBG及更短光纤的高效Er3+-Yb3+共掺双包层光纤放大器 总被引:2,自引:2,他引:0
提出在光纤放大器中,使用光纤布喇格光栅作为泵浦光反射镜,所需的双包层光纤可以缩短,同时至少保持了与没有光纤布喇格光栅作为反射镜时光纤放大器相同的性能.基于速率及传输方程,对使用和不使用光纤布喇格光栅的铒、镱共掺双包层光纤放大器的性能进行了数值模拟.结果表明,使用光纤布喇格光栅作为反射镜时光纤放大器可以获得与无光栅时相同的输出功率,但仅仅需要后者长度一半的光纤,无论是前向泵浦还是后向泵浦.对后向泵浦方式并使用光纤布喇格光栅作为反射镜,可获得最高的输出功率及光增益,同时使用了较短的光纤. 相似文献
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J.-P. Negel R. Hegenbarth A. Steinmann B. Metzger F. Hoos H. Giessen 《Applied physics. B, Lasers and optics》2011,103(1):45-50
We demonstrate a compact and cost-effective setup to generate broadband THz radiation. As pump source we use a diode-pumped
solid-state femtosecond oscillator or a femtosecond fiber laser system, partially in combination with an optical parametric
oscillator. For the THz generation we utilize optical rectification in gallium phosphide (GaP) and gallium arsenide (GaAs).
The THz power is on the order of 1 μW and we demonstrate imaging and spectral measurements with this setup. 相似文献
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在基于掺铒光纤-拉曼混合放大的可调光纤环形激光器的光纤布拉格光栅(FBG)传感系统结构基础上,提出了延长传感距离的新方法。该方法以环形掺铒光纤激光器作为光源,采用双波长拉曼放大的方法对信号进行低噪声的双向放大,系统中间的两段掺铒光纤再利用剩余的抽运功率产生自发辐射光和放大传感信号,使得整个系统能够在超长的传感距离上获得很高的信噪比。实验表明使用一只40 mW的掺铒光纤放大(EDFA)抽运源、一只170 mW的拉曼抽运源和一只2 W的拉曼抽运源,可以使整个系统的传感距离达到100km,并且传感系统的光纤布拉格光栅反射信号均能获得超过57 dB的优良信噪比,从而实现在超长距离上的光纤布拉格光栅传感。 相似文献
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采用改进的化学气相沉积法和溶液掺杂法制备出掺镱石英光纤预制棒,以该预制棒为有源纤芯制备芯区直径约为30μm的双包层保偏掺镱光子晶体光纤.模拟计算得到该保偏光纤的模场面积约232μm2,双折射系数B为5×10-5.利用该光纤分别进行了脉冲激光和连续激光的放大测试实验,在国内首次实现了高效率的飞秒激光放大,2 m长的光子晶体光纤可得到1.64 W的激光输出,激光放大斜率效率为49.8%.同时5 m长的光纤还能够实现8.12 W的连续激光放大输出,斜率效率达到55.9%,具有较高的斜率效率.此外,该光纤消光比约10 dB,具有良好的保偏特性. 相似文献
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We report on a high-power, high-energy femtosecond fiber source based on direct amplification of parabolic pulses from an environmentally stable passively mode-locked fiber oscillator in an Yb-doped single-polarization photonic crystal fiber. The special pulse shape allows for the generation of high-quality femtosecond pulses beyond nonlinearity limits. The system delivers a pulse energy of 1.2 microJ (21 W average power) at a repetition rate of 17 MHz and a pulse duration of 240 fs in a linearly polarized beam with diffraction-limited quality. 相似文献
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Femtosecond 5-W Yb:KGW slab laser oscillator pumped by a single broad-area diode and its application as supercontinuum source 总被引:1,自引:0,他引:1
F. Hoos T. P. Meyrath S. Li B. Braun H. Giessen 《Applied physics. B, Lasers and optics》2009,96(1):5-10
We demonstrate a novel and very simple design for an efficient high-power femtosecond Yb:KGW slab laser oscillator. The laser
is capable of producing output powers of more than 5 W at 44-MHz repetition rate and pulse widths as short as 161 fs with
a nearly diffraction limited beam and an optical-to-optical efficiency of more than 28%. The laser is pumped by a single broad-area
laser diode and employs simple pump optics consisting of three lenses. The laser output power is distributed between two beams
and single or combined outputs are discussed. In combination with a tapered fiber the laser was used to generate femtosecond
supercontinua with up to 1.3-W average power and spectra spanning from 420 to over 1750 nm. 相似文献
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In this paper the gain characteristics of two-pump fiber optical parametric amplifiers (FOPA) with two-section highly nonlinear fibers are analyzed numerically and the parameters of the fibers are optimized to reach broad and flat gain spectra using genetic algorithm. Different from the previous methods, here the space between two pump wavelengths and the parameter β4 of the fibers are included as a pivotal factor in the optimization. The numerical simulation shows that using two-section practical high nonlinear fibers, the amplifier may reach 110 nm bandwidth covering 1495–1605 nm with 10.5 dB average gain and gain ripple of 0.17 dB, when the total pump power is 1 W. 相似文献