共查询到20条相似文献,搜索用时 31 毫秒
1.
L. J. Wang Y. Yang Y. G. Zeng L. J. Wang C. Z. Tong X. N. Shan H. X. Zhao R. Wang S. F. Yoon 《Applied physics. B, Lasers and optics》2012,107(3):809-812
We report on 980-nm InGaAs/GaAs lasers with dual-lobed far field based on a single-sided Bragg reflection waveguide (BRW). The high slope efficiency ~0.92 W/A and a continuous wave (CW) output power >1.5 W (3.2 W pulsed) have been obtained. The threshold current density is as low as 253 A/cm2 for a 1.5-mm-long device and the transparency current density is only 140 A/cm2. The further analysis shows the intrinsic reason for the single-lobed or the dual-lobed far-field distribution is determined by the mode shape in the cavity, not the single-sided or dual-sided BRW structure. The condition to achieve a narrow single-lobed far-field distribution is discussed. 相似文献
2.
A terahertz 1D photonic crystal cavity with very high Q-factor is demonstrated. The cavity consists of two parallel distributed Bragg mirrors and one air layer between them as defect layer. By increasing the length of the defect layer, the cavity has a very narrow transmission bandwidth of 30 MHz at resonant frequency of 336 GHz, i.e., a high Q over 1.1 × 104 is achieved. Furthermore, an optically controllable THz switch is demonstrated by light irradiating on one of the middle silicon wafer in the cavity. And the power of optical beam needed for the switch is remarkably reduced to 0.16 W/cm2, which is nearly 50 times smaller than that for a THz switch using a single silicon wafer. 相似文献
3.
Christian Fiebig J?rg Fricke Mirko Uebernickel Daniel Jedrzejczyk Alexander Sahm Katrin Paschke 《Optical Review》2012,19(6):405-408
Large-area high-resolution displays, using a flying-spot to create the picture, require light sources in the red, green and blue wavelength range with a high optical output power and nearly diffraction limited beam. In this paper we present experimental results of high-brightness distributed Bragg reflector tapered diode lasers at 106x nm that can be used for single-pass second harmonic generation into the green. Based on these lasers we developed compact (2.5 cm3) green laser modules with an output power of 1W at 53x nm and an electro-optical conversion efficiency of about 5%. The output power stability is better than 2% and the wavelength stability is ±10 pm. The excellent beam quality M ?? 2 < 2 of the green light allows operation in flying spot application systems. Furthermore, we estimate that our concept allows power scaling up to 2W by using nonlinear planar waveguide crystals and into the multi-watt level by spectral beam combining. 相似文献
4.
The disorders induced in crystalline silicon (c-Si) through the process of electronic energy loss in the swift heavy ion irradiation were investigated. A number of silicon <1 0 0> samples were irradiated with 65 MeV oxygen ions at different fluences, 1×1013 to 1.5×1014 ions/cm2, and characterized by the Raman spectroscopy, the optical reflectivity, the X-ray reflectivity, the atomic force microscopy (AFM) and the X-ray diffraction (XRD) techniques. The intensity, redshift, phonon coherence length and asymmetric broadening associated with the Raman peaks reveal that stressed and disordered lattice zones are produced in the surface region of the irradiated silicon. The average crystallite size, obtained by analyzing Raman spectrum with the phonon confinement model, was very large in the virgin silicon but decreased to<100 nm dimension in the ion irradiated silicon. The results of the X-ray reflectivity, AFM and optical reflectivity of 200–700 nm radiation indicate that the roughness of the silicon surface has enhanced substantially after ion irradiation. The diffusion of oxygen in silicon surface during ion irradiation is evident from the oscillation in the X-ray reflectivity spectrum and the sharp decrease in the reflectivity of 200–400 nm radiation. The rise in temperature, estimated from the heat spike model, was high enough to melt the local silicon surface. The results of XRD indicate that lattice defects have been induced and a new plane <2 1 1> has been formed in the silicon <1 0 0>after ion irradiation. The results of the present study show that the energy deposited in crystalline silicon through the process of electronic energy loss ~0.944 keV/nm per ion is sufficient to induce disorders of appreciable magnitude in the silicon surface even at a fluence of ~1013 ions/cm2. 相似文献
5.
Adnan Ali Jeongdai Jo Young Jin Yang Kyung Hyun Choi 《Applied Physics A: Materials Science & Processing》2014,114(2):323-330
Graphene-based composites represent a new class of materials with potential for many applications. Graphene can be attached to a metal, a semiconductor, or any polymer for enhancing properties. In this work, a new mixed dispersion approach for graphene-based composite has taken on. Graphene flakes (<4 layers) and a well-known semiconductor zinc oxide (ZnO) (<50 nm particle size) have dispersed in N-methyl-pyrrolidone. We deposited graphene/ZnO composite thin film by a simple, low-cost, environmentally friendly and non-vacuum electrohydrodynamic atomization process on silicone substrate. Experiments have been carried out by changing flow rate and applied potential while keeping stand-off distance and substrate velocity constant, to discover the optimum conditions for obtaining a high-quality thin film. It has been explored that high-quality thin composite film is obtained at optimum flow rate of 300 μl/h at 6.3 kV applied potential after curing for 2 h at 300 °C. Graphene/ZnO thin composite film has been characterized using Field emission scanning electron microscopy, Ultra-violet Visible near Infra Red spectroscopy, X-ray diffraction, Raman Spectroscopy and 3D-Nanomap. For electrical behavior analysis, a simple diode Indium tin oxide/(poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS)/polydioctylfluorene-benzothiadiazole(F8BT)/(Graphene/ZnO) has fabricated. It is observed that at voltage of 0.3 V, the current in organic structure is at low value of 1.20 × 10?3 Amp/cm2 and after that as further voltage was applied, the device current increased by the order of 110 and reaches up to 1.32 × 10?1 Amp/cm2 at voltage 2 V. 相似文献
6.
L. Daniault D. A. Gaponov M. Hanna S. Février P. Roy F. Druon P. Georges M. E. Likhachev M. Y. Salganskii M. V. Yashkov 《Applied physics. B, Lasers and optics》2011,103(3):615-621
We report on high power amplification of femtosecond pulses in 40-μm core diameter Yb-doped photonic bandgap Bragg fibers.
The robustness to bending and transverse spatial behavior of these fibers is analyzed through simulations. The fibers are
used in both stages of a moderately stretched (150 ps) femtosecond chirped pulsed amplification (CPA) system. A compressed
average power of 6.3 W is obtained using a low-index polymer-coated Bragg fiber with excellent beam quality and high efficiency,
in agreement with numerical simulations. The use of an air-clad Bragg fiber allows us to scale the output power to 47 W at
a repetition rate of 35 MHz. This experiment demonstrates the great potential of Bragg fibers to increase the mode area and
the power of practical bending-tolerant femtosecond fiber systems. 相似文献
7.
A high-power master-oscillator power-amplifier with optical vortex output is reported. The master oscillator for an optical vortex seed beam is a simple two-mirror Nd:YAG laser using a fiber-based pump beam conditioning scheme. The seed is amplified in a double-clad multimode fiber amplifier end-pumped by a high-power diode laser at 975 nm yielding 10.7 W of continuous-wave output at 1064 nm in the first-order Laguerre–Gaussian beam with M 2 ≈ 2.11 for an absorbed pump power of 17.5 W, corresponding to a slope efficiency of ~59 %. The ring-shaped intensity profile and the wave front handedness of the seed beam were well preserved in the fiber amplifier. The prospects of power scaling via this approach are discussed. 相似文献
8.
Fen Bai Qingpu Wang Zhaojun Liu Xingyu Zhang Weixia Lan Xutang Tao Youxuan Sun 《Applied physics. B, Lasers and optics》2013,112(1):83-87
An idler-resonant KTiOAsO4 (KTA) optical parametric oscillator is demonstrated within a diode-end-pumped acousto-optically Q-switched Nd:YAG laser. With an X-cut KTA crystal, idler wave at 3467 nm and signal wave at 1535 nm are generated. Under an incident diode pump power of 15.4 W, the idler output power of 105 mW and signal power of 720 mW are obtained at a pulse repetition rate of 40 kHz. The pulse widths of the idler and signal waves are 7.2 and 3.1 ns, respectively. The beam quality factors (M2) of the idler wave are within 1.2 in both horizontal and vertical directions. 相似文献
9.
We present the strict design parameters of the experiment for the 780 nm tunable continuous-wave second harmonic (SH) generation by the nonlinear resonator containing a MgO doped periodically poled LiNbO3 (MgO:PPLN) crystal. Optimization of such critical parameters, including focusing and impedance matching, more than 84% SH conversion efficiency and 3.1 W available output power at 780 nm were obtained from the fundamental wave at 1560 nm with two different input couplers. The thermal saturated behavior of the SH output power has been observed in the experiment. The beam quality factor M2 of the generated SH wave is 1.04 (1.03), and the RMS power stability is 1.29% in 3 h. The SH wave was further used to detect the D 2 transitions of Rb atom, exhibiting a fine tunable characteristic. Such laser source can be a suitable candidate in the atomic physics and quantum optics. 相似文献
10.
Xin Zhang Weifeng Diao Yuan Liu Jiqiao Liu Xia Hou Weibiao Chen 《Applied physics. B, Lasers and optics》2014,115(1):123-127
An all-fiber, single-frequency, linearly polarized, high peak-power, pulsed laser at 1,540 nm for Doppler wind lidar is presented. This laser is composed of a single-frequency, narrow-linewidth external cavity diode laser, and multistage fiber amplifiers. A peak power of 1.08 kW and a pulse width of 500 ns at 10 kHz repetition rate are achieved, which is the highest peak power with a linewidth of 800 kHz in erbium-doped silica fiber to our knowledge. The beam quality of M 2 < 1.3 and a polarization extinction ratio over 16 dB are obtained. This laser will be employed in a compact long-range coherent Doppler wind lidar. 相似文献
11.
A. Picciotto L. Torrisi S. Gammino A. M. Mezzasalma F. Caridi D. Margarone 《辐射效应与固体损伤》2013,168(10-12):705-713
The temperature of laser-generated pulsed plasmas is an important property that depends on many parameters, such as the particle species and the time elapsed from the laser interaction with the matter and the surface characteristics. Laser-generated plasmas with low intensity (<1010 W/cm2) at INFN-LNS of Catania and with high intensity (>1014 W/cm2) in PALS laboratory in Prague have been investigated in terms of temperatures relative to ions, electrons, and neutral species. Time-of-flight (ToF) measurements have been performed with an electrostatic ion energy analyzer (IEA) and with different Faraday cups, in order to measure the ion and electron average velocities. The IEA was also used to measure the ion energy, the ion charge state, and the ion energy distribution. The Maxwell–Boltzmann function permitted to fit the experimental data and to extrapolate the ion temperature of the plasma core. The velocity of the neutrals was measured with a special mass quadrupole spectrometer. The Nd:Yag laser operating at low intensity produced an ion temperature core of the order of 400 eV and a neutral temperature of the order of 100 eV for many ablated materials. The ToF of electrons indicates the presence of hot electron emission with an energy of ~1 keV. 相似文献
12.
Stable, high-power, second-harmonic-generation (SHG) of a compact CW Ytterbium (Yb) fiber laser at 1064 nm into the green
and its use as a pump source for CW singly-resonant optical parametric oscillator (SRO) is demonstrated. Using a simple single-pass
SHG configuration in MgO:sPPLT, as much as 9.6 W of single-frequency green radiation at 532 nm is generated from 30 W of fundamental
power at a conversion efficiency of 32.7% in a Gaussian spatial profile with a beam quality factor of M
2 < 1.3. Thermal effects have been investigated at different fundamental power levels and various thermal management schemes
are employed to maximize the second-harmonic power. The green source is successfully deployed to pump a CW SRO tunable over
855–1408 nm, generating up to 2.1 W of idler at 1168 nm. The peak-to-peak idler power stability is better than 10.7% over
40 min, with beam quality factor M
2 < 1.26 for the idler and M
2 < 1.52 for the signal. 相似文献
13.
A modified two-path confocal microscope was used to obtain fluorescence images of a Nd:YAG microchip element in the presence of a tightly focused 808 nm pump beam. Based on the temperature-induced homogeneous line broadening, high-resolution (<1 μm, <1°C) thermal images of the pump volume and surroundings were obtained from the spatial variation of Nd3+ linewidth. Based on this direct, pure optical and non-contact method, thermal gradients as low as 0.02°C/μm were detected at focal volume, this being in agreement with theoretical predictions. The thermal imaging technique here presented opens the possibility of accurate compensation of thermal effects for the development of stable and efficient microchip lasers. 相似文献
14.
Taymour A. Hamdalla 《Current Applied Physics》2013,13(3):533-536
We present the effect of gamma radiation on the selectivity of the Nonlinear Apodized Chirped Bragg Grating (NACBG). As the shift in the wavelength selection for the nonlinear fiber Bragg grating is investigated. Also trial has been made to calculate this shift for the high power signals (n2 = 2.6 × 10?20 W/m2). Comparison between the irradiated and unirradiated NACBG has been investigated. The optimum profile is investigated. It is found that the tanh profile is the greatest profile affected by radiation, it has error of about 0.62 nm at the sea level, while Hamming profile is the smallest one, with an error of 0.36 nm at the sea level. 相似文献
15.
Kai Seger Niels Meiser Staffan Tjörnhammar Andrius Zukauskas Carlota Canalias Valdas Pasiskevicius Fredrik Laurell 《Applied physics. B, Lasers and optics》2014,115(2):161-166
An Yb:KYW laser intra-cavity frequency doubled to the green at 514.7 nm using a periodically poled Rb:KTP crystal with an output power exceeding 1 W is presented. Spectral narrowing and locking at the fundamental wavelength has been achieved by using a volume Bragg grating as the input coupler. 相似文献
16.
J. Kwiatkowski J. K. Jabczynski W. Zendzian L. Gorajek M. Kaskow 《Applied physics. B, Lasers and optics》2014,114(3):395-399
We describe an efficient, low-threshold, continuous-wave (CW) and Q-switched operation of a Ho:YAG laser resonantly, single-pass pumped by a 20 W linearly polarized narrow line width Tm: fiber laser at the wavelength of 1,908 nm. At room temperature for an output coupler of 30 % transmission, a maximum continuous-wave output power of 13.3 W for 18.9 W of absorbed pump power was achieved, corresponding to a slope efficiency of 73 %. In a quasi continuous-wave pumping regime, for several output couplers slope efficiencies of almost 82 % were observed. For a Q-switched operation, a Brewster-cut acousto-optic modulator was used. In a CW pumping regime, the pulse repetition frequency (PRF) was changed from 4 to 15 kHz. Under a Q-switched operation, the maximum output power of 12.25 W in relation to 15 kHz PRF was obtained; however, the maximum peak power of almost 250 kW at the PRF of 4 kHz was demonstrated. In the best case, for 4 kHz PRF, pulse energies of 2.18 mJ with a 8.8 ns FWHM pulse width (one of the shortest pulse durations observed in holmium-doped Q-switched lasers) were achieved. The laser operated at the wavelength of 2,090.23 nm with the FWHM line width of 0.95 nm. The beam quality factor of M 2 was measured to be below 1.42 in both X and Y axis. 相似文献
17.
Shengju?Wu Fengting?Li Ran?Xu Shihui?Wei Guangtao?Li 《Journal of nanoparticle research》2010,12(6):2111-2124
Thiol-functionalized MCM-41 mesoporous silicas were synthesized via evaporation-induced self-assembly. The mesoporous silicas obtained were characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption analysis, Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The products were used as adsorbents to remove heavy metal ions from water. The mesoporous silicas (adsorbent A) with high pore diameter (centered at 5.27 nm) exhibited the largest adsorption capacity, with a BET surface area of 421.9 m2 g?1 and pore volume of 0.556 cm3 g?1. Different anions influenced the adsorption of Cu(II) in the order NO3 ? < OAc? < SO4 2? < CO3 2? < Cit? < Cl?. Analysis of adsorption isotherms showed that Cu2+, Pb2+, Ag+, and Cr3+ adsorption fit the Redlich–Peterson nonlinear model. The mesoporous silicas synthesized in the work can be used as adsorbents to remove heavy metal ions from water effectively. The removal rate was high, and the adsorbent could be regenerated by acid treatment without changing its properties. 相似文献
18.
E. Karamehmedovi? C. Pedersen O. B. Jensen P. Tidemand-Lichtenberg 《Applied physics. B, Lasers and optics》2009,96(2-3):409-413
We investigate the possibility of improving the beam quality and obtaining high conversion efficiency in nonlinear sum-frequency generation. A 765 nm beam from an external cavity tapered diode laser is single-passed through a nonlinear crystal situated in the high intracavity field of a 1342 nm Nd:YVO4 laser, generating a SFG beam at 488 nm. The ECDL have M H 2 =1.9 and M V 2 =2.4 and the solid-state laser has M 2<1.05. Varying the focusing of the 765 nm beam, the conversion efficiency and the beam quality of the generated 488 nm beam change correspondingly. We show that it is possible to improve the M 2 of the 488 nm beam to less than 1.3 while preserving a high conversion efficiency of the SFG process. 相似文献
19.
J. Liu Z. Shao H. Zhang X. Meng L. Zhu M. Jiang 《Applied physics. B, Lasers and optics》1999,69(3):241-243
A diode-laser-array end-pumped efficient CW Nd:GdVO4 laser at 1.06 μm has been developed. A low-order-mode output power of 14.3 W was obtained at the maximum available pump power
of 26 W, giving an optical conversion efficiency of 55% and an average slope efficiency of 62%. The laser output beam quality
factor at full pump power was determined to be M2<1.8. It is also shown that only lightly doped Nd:GdVO4 crystals are suitable for high-power end-pumped lasers.
Received: 4 May 1999 / Published online: 29 July 1999 相似文献
20.
Ge and Ta ion implantation of silicon and carbon substrates has been obtained at PALS Research Laboratory in Prague by using laser pulses of 400 ps duration, 438 nm wavelength, 1014?16 W/cm2 intensity. Substrates were exposed in vacuum at different distances from the target and at different angles with respect to the normal to the target surface. ‘On line’ measurements of ion energy were obtained with time-of-flight techniques by using an electrostatic deflector as ion energy analyzer. ‘Off line’ measurements of ion energy were obtained by Rutherford backscattering spectrometry (RBS) of 2.25 MeV He2+ beam at CEDAD Laboratory of Lecce University. The RBS spectra have given the depth profiles of the ion-implanted species and the implanted doses as a function of the laser intensity, angular position and target distance. A spectra deconvolution method based on the ion stopping power in the substrate matrix was applied in order to evidence the energy of the implanted ions. Measurements indicate that ions with energy ranging between 100 keV and 10 MeV and dose of the order of 1014?16/cm2 are implanted and that the process of ion implantation occurs mainly in substrates placed at little angles with respect to the normal to the target surface. Only a thin film deposition occurs for substrates placed at large angles with respect to the normal direction. Results indicate that the ion energies measured with the ‘on line’ and the ‘off line’ techniques are in good agreement. 相似文献