共查询到20条相似文献,搜索用时 15 毫秒
1.
Dongqing Pang Yunxuan Li Qingyue Wang 《Applied Physics A: Materials Science & Processing》2014,115(4):1181-1185
Resonant ablation is beneficial to avoiding uncontrollable subsurface damages in the laser ablation of polymers. In this paper the dynamics of mid-infrared laser resonant ablation of polylactic acid and toluene was calculated by using fluid dynamic equations. The merits and drawbacks of mid-infrared femtosecond laser resonant ablation of high molecular weight polymers have been discussed. 相似文献
2.
The laser-driven acceleration of high quality proton beams from a double-layer target, comprised of a high-Z ion layer and a thin disk of hydrogen, is investigated with three-dimensional particle-in-cell simulations for an obliquely incident laser pulse. The proton beam energy reaches its maximum at a certain incidence angle, where it can be much greater than the energy at normal incidence. The proton beam propagates at some angle with respect to the target surface normal and with some tilt around the target surface, as determined by the proton energy and the incidence angle. 相似文献
3.
A cw laser-diode-pumped Yb-doped double-clad fiber laser operating in a hybrid Q-switched regime was demonstrated. The output pulses had a duration as short as 4.2 ns, a tunable wavelength range from 1080.8 to 1142.7 nm, and a linewidth of less than 0.05 nm. Maximum peak power of approximately 175 kW and single-pulse energy of 1.57 mJ were obtained. 相似文献
4.
Martin Schellhorn Marc Eichhorn Christelle Kieleck Antoine Hirth 《Comptes Rendus Physique》2007,8(10):1151-1161
An efficient, high-power mid-infrared laser source based on ZnGeP2 (ZGP) optical parametric oscillator (OPO) is presented. Using a Q-switched Ho:YAG laser as the pump source a total output power of 10.6 W was obtained in the 3–5 μm band at 10 kHz and 8.5 W at 20 kHz. The Ho:YAG laser was pumped by two diode-pumped polarization coupled Tm:YLF lasers. Optical-to-optical efficiency achieved is >8.8% (laser-diode 792 nm to mid-IR 3–5 μm). With a commercial PtSi infrared camera (256×256 pixel focal plane array, 24 μm pitch) the pointing stability of Ho pump, signal and idler beam was measured to be better than 30 μrad. Whilst propagating the OPO beams over 100 m, little absorption for the idler beam was observed, resulting in a significant higher peak-to-peak value of ±22%, whereas the peak-to-peak stability of the signal pulses remained unchanged (±13%). To cite this article: M. Schellhorn et al., C. R. Physique 8 (2007). 相似文献
5.
We report on a broadly tunable, long-cavity Ti:sapphire laser oscillator being mode-locked in the net negative intracavity
dispersion regime by Kerr-lens mode-locking, delivering τ
FWHM<300 fs pulses at 22 MHz repetition rate. The wavelength of the laser can be tuned over a 170 nm wide range between 712 nm
and 882 nm. Having a typical pump power of 2.6 W, the maximum pulse peak power is 60 kW. Comparison of the reported laser
with a standard, 76 MHz Ti:sapphire oscillator regarding two-photon excitation efficiency in a laser scanning microscope shows
that the 22 MHz laser generates the same fluorescence signal at considerably, 1.82 times lower average power, which is expected
to result in a reduced photothermal damage probability of biological samples. This fact along with the broad tunability and
a low pump power requirement makes this cost-effective laser an ideal light source for nonlinear microscopy. 相似文献
6.
We present a scheme to produce programmable phase- and amplitude-modulated femtosecond laser pulses in the mid-infrared regime of 3-10mum by difference frequency mixing. The 80-fs signal output of an optical parametric amplifier is shaped with a liquid-crystal mask and mixed in an AgGaS(2) crystal with a temporally stretched idler pulse. Without changing the mechanical alignment, we produce programmable amplitude modulations and chirped pulses at lambda=3mum with energy as high has thas 1muJ . This scheme, further, allows the generation of controllable pulse sequences. The results are in good agreement with theoretical simulations. 相似文献
7.
We report on the design and characterization of a highly coherent mid-IR source at 3.57mum based on a single-frequency optical parametric oscillator. Detailed frequency and amplitude noise spectra have been measured. The rms intensity noise from 1.2 to 1000 Hz was 0.03%, and a rms frequency drift of 8 kHz in 1 ms was observed. We have also demonstrated the utility of this source for coherent laser radar applications by measuring micro-Doppler spectra from vibrating targets. 相似文献
8.
This paper reports that the tunable self-phase-stabilized infrared
laser pulses have been generated from a two-stage optical parametric
amplifier. With an 800 nm pump source, the output idler pulses are
tunable from 1.3 μm to 2.3 μm, and the maximum output
energy of the idler pulses is higher than 1 mJ at 1.6 μm by
using 6 mJ pump laser. A carrier-envelope phase fluctuation of
~ 0.15 rad (rms) for the idler pulses is measured for longer
than one hour by using a home build f-to-2f interferometer. 相似文献
9.
We present a tunable, ultrafast, mid-infrared source based on difference frequency between 16?μm and 20?μm from an ultrafast, two-color Yb:fiber chirped-pulse amplifier. We have recorded an average power of 1.5?mW at ~18 μm. We have improved the output power after the pre-amplifier by one order of magnitude. We present the simulation and experimental results to the pre-amplifier. 相似文献
10.
Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses 总被引:1,自引:0,他引:1
Nejadmalayeri AH Herman PR Burghoff J Will M Nolte S Tünnermann A 《Optics letters》2005,30(9):964-966
For the first time to the authors' knowledge, optical waveguides have been inscribed in bulk crystalline silicon by ultrafast laser radiation. Femtosecond laser pulses of 40-nm spectral bandwidth, 1-kHz repetition rate, and 1.7-microJ on-target energy were applied at a mid-infrared wavelength of 2.4 microm to induce nonlinear absorption in the focal volume of the beam. By scanning the laser beam with respect to the sample, buried optical waveguides have been created that were single mode at 1550 and 1320 nm and guided light only with its polarization perpendicular to the sample's surface. Propagation losses with an upper limit of 1.2 dB/cm or less were observed throughout the optical telecommunications band. 相似文献
11.
Narrow bandwith tunable Q-switched operation of an alexandrite oscillator was used for injection-locking of a high-energy alexandrite slave ring laser. Pulses with up to 600 mJ in energy over a 600 cm–1 tuning range were obtained. 相似文献
12.
We have demonstrated a chirped-pulse-amplification system utilizing an air-spaced etalon inside a regenerative amplifier to produce two simultaneous 2.0-ps pulses, one centered at the gain peak of Nd:phosphate glass (1052 nm) and the other centered at the gain peak of Nd:silicate (1061 nm). Autocorrelations of the resulting beat wave demonstrate a beat frequency of 2.3 THz. We achieved wavelength tunability over a 10-nm range by electronically adjusting the etalon spacing and variable pulse width by changing the etalon rotation. 相似文献
13.
A two-propagation-axis solid-state laser is shown to provide a widely tunable optical microwave source. The spatial separation of the laser eigenstates is shown to enable an étalon to act as a coarse tuner, forcing oscillation in any nonadjacent cavity modes. The frequency difference between opposite helicoidal eigenstates operating in nonadjacent cavity modes can then be tuned continuously. The beat note from such a solid-state laser is shown to vary from dc to 26 GHz, i.e., 30 times the laser free-spectral range, and is limited only by the free-spectral range of the étalon. 相似文献
14.
A.S. Aleksandrovsky A.M. Vyunishev A.I. Zaitsev A.V. Zamkov 《Optics Communications》2009,282(11):2263-2266
Efficient tunable femtosecond phase-matched noncollinear second-harmonic generation in randomized nonlinear photonic crystal of strontium tetraborate is obtained. Spatial spectrum of nonlinear photonic structure is not flat but enables tuning of the harmonic frequency in the range from 355 to 460 nm. The narrowing of the bandwidth of second harmonic is found to be of order of 10-20%. 相似文献
15.
Chunmei Zhang Jianliang Wang Xiaowei Chen Yuxin Leng Ruxin Li Zhizhan Xu 《Laser Physics》2009,19(8):1793-1795
The seventh harmonic generation by tunable mid-infrared femtosecond pulses filamentation in air is observed first time. Pumped by a focused mid-infrared pulses, which pulse duration is ~50 fs and wavelength is tunable from 1300 to 2000 nm, the tunable region of the fifth and seventh harmonic generation can cover the near ultraviolet region from 180 to 400 nm. 相似文献
16.
Two continuous-wave single mode diode-lasers (Hitachi HL 7851G and Toshiba TOLD 9150) are applied as signal and pump sources for difference frequency generation (DFG) in an AgGaS2 crystal with a length of 30 mm. For 90° type I phase matching tunable mid-infrared laser radiation around 5 µm is obtained with an output power of up toP
DFG = 0.2 µW while the diode lasers are operated with powers of 30 and 50 mW at the center wavelengths 682 and 791 nm, respectively. The performance of the diode-laser-DFG system is shown as the absorption spectrum of CO for the P(28) rotational line around 2023 cm–1 is probed in a 10cm long cell and in the exhaust of an engine.This research was supported by the Technologiestiftung Schleswig-Holstein under contract 94-35i. 相似文献
17.
We report here on a diode-pumped pulsed mid-infrared laser source based on gas-filled hollow-core fibers(HCFs)towards an all-fiber structure by the tapering method. The pump laser is coupled into an acetylene-filled HCF through a tapered single-mode fiber. By precisely tuning the wavelength of the diode to match different absorption lines of acetylene near 1.5 μm, mid-infrared emission around 3.1–3.2 μm is generated. With 2 m HCFs and3 mbar acetylene gas, a maximum average power of 130 m W is obtained with a laser slope efficiency of ~24%.This work provides a potential scheme for all-fiber mid-infrared fiber gas lasers. 相似文献
18.
Second harmonic generation by femtosecond Yb-doped fiber laser source based on PPKTP waveguide fabricated by femtosecond laser direct writing 总被引:1,自引:0,他引:1
The frequency doubling of femtosecond pulses from an Yb-doped fiber laser source was demonstrated in a PPKTP waveguide fabricated by femtosecond laser direct writing. The PPKTP waveguide contains a fixed period of 8.9 μm and the feomtosecond fundamental pulses have a central wavelength of 1044 nm. A maximum SHG power of 406 mW was produced, yielding a conversion efficiency of 5.6%. Numerical simulations were carried out to investigate the property of frequency doubling for femtosecond pulses. The results show that the SHG process proceeds even the quasi-phase-matching (QPM) condition is not well satisfied, which is significantly different from that of “long” pulses or CW light and is accorded with the experimental results. 相似文献
19.
Spatial distribution of high-energy electron emission from water plasmas produced by femtosecond laser pulses 总被引:1,自引:0,他引:1
Li YT Zhang J Sheng ZM Teng H Liang TJ Peng XY Lu X Li YJ Tang XW 《Physical review letters》2003,90(16):165002
High energy electrons emitted by water plasmas produced by a single or a multiple laser pulse are investigated. The multipulse mode greatly enhances the generation and the temperature of hot electrons. Directional emission of high energy electrons over 25 keV is observed in two symmetric directions with respect to the laser axis and at 46 degrees from the directions of the laser electric field. Two-dimensional particle-in-cell simulations reproduce well the experimental results and indicate that the acceleration mechanism of the high energy electrons is due mainly to the resonance absorption at the edge of the spherical droplets formed by the leading pulse. 相似文献
20.
We report efficient generation of tunable femtosecond pulses in the ultraviolet (UV) by intracavity doubling of a visible femtosecond optical parametric oscillator (OPO). The OPO, based on a 400 microm BiB3O6 crystal and pumped at 415 nm in the blue, can provide visible femtosecond signal pulses across 500-710 nm. Using a 500 microm crystal of beta-BaB2O4 internal to the OPO cavity, efficient frequency doubling of the signal pulses into the UV is achieved, providing tunable femtosecond pulses across 250-355 nm with up to 225 mW of average power at 76 MHz. Cross-correlation measurements result in UV pulses with durations down to 132 fs for 180 fs blue pump pulses. 相似文献