共查询到20条相似文献,搜索用时 15 毫秒
1.
Y. Li P. Lu N. Dai X. Wang Y. Wang B. Yu H. Long 《Applied physics. B, Lasers and optics》2007,88(2):227-230
Surface relief diffraction gratings were written at the entrance surface of a β-BaB2O4 (BBO) crystal under irradiation with femtosecond laser pulses. Probe–beam diffraction and atomic force microscopy (AFM) were
employed to characterize the diffraction properties and the microstructures of the gratings. The maximal first-order diffraction
efficiency of these gratings is approximately 63%. The surface periodic structure of the material induces noncollinear propagation
of the fundamental input beam in the crystal. Using this diffractive optical element, efficient generation of multiple second-harmonic
beams was achieved.
PACS 42.79.Dj; 42.40.Lx; 42.65.–k 相似文献
2.
We presented a microfabrication process for optical volume vortex grating inside glass by femtosecond laser pulses. The self-trapped filament of femtosecond laser pulses can induce hundreds μm-long region refractive-index changes in glass. We realized the restructured optical vortex beams using a collimated He–Ne laser beam. The maximum first-order diffraction efficiency was about 19.6%. The volume vortex grating structure fabricated in glass is polarization dependent. 相似文献
3.
Stuart BC Perry MD Miller J Tietbohl G Herman S Britten JA Brown C Pennington D Yanovsky V Wharton K 《Optics letters》1997,22(4):242-244
We have demonstrated a Ti:sapphire/Nd:glass laser system that produces up to 51 J of energy in 395-fs pulses (125TW). Focusing at f/3 to a 2.5-times diffraction-limited spot results in a peak irradiance greater than 10(20) W/cm(2) . Our 40-cm-diameter gold diffraction gratings have a damage threshold of 0.42 J/cm(2) for 320-fs pulses. 相似文献
4.
Tiled-grating compression of multiterawatt laser pulses 总被引:1,自引:0,他引:1
High-energy petawatt lasers require large diffraction gratings for pulse compression. As an alternative to meter-sized gratings, we demonstrate the capability of a tiled-grating system to compress multiterawatt subpicosecond laser pulses. Using a 100 TW-class Nd:glass chirped-pulse amplification laser facility, we report on the performance of a two-grating mosaic to compress high-energy pulses to 2.5 J, 450 fs (5.5 TW) in air with a beam size of 50 mm and energy transmission of 63%. Stability of the grating mosaic alignment was realized by use of an accurate nanopositioning optomechanical system. The output Gaussian spectrum was preserved from grating-gap spectral clipping and was free of modulation. 相似文献
5.
K. Kawamura T. Ogawa N. Sarukura M. Hirano H. Hosono 《Applied physics. B, Lasers and optics》2000,71(1):119-121
Fabrication of surface relief-type gratings in transparent dielectrics, which are hard to machine, has been achieved by a
holographic technique using two infrared femtosecond (fs) pulses from a mode-locked Ti:sapphire laser. The present method
can be applied for a variety of transparent dielectrics, Al2O3 (sapphire), TiO2, ZrO2, LiNbO3, SiC, ZnO, CdF2, MgO, CaF2 crystals, and SiO2 glass. It is found that the grating formation is due primarily to laser ablation processes. Planar surface relief gratings
can be fabricated by colliding two fs laser pulses on the surface of substrates which move at a constant speed, synchronized
with the laser repetition rate.
Received: 1 March 2000 / Published online: 7 June 2000 相似文献
6.
A novel and rapid laser ablation method for the fabrication of phase diffractive gratings in low-cost glass substrates is presented. The structures are characterized in terms of their shape and physical parameters by confocal microscopy and SEM microscopy. The first-order diffraction efficiency at normal incidence under 632.8 nm wavelength is shown. The influence of the overlap factor on the period grating is studied. 相似文献
7.
High-efficiency fused-silica transmission gratings 总被引:2,自引:0,他引:2
We describe the design, fabrication, and performance of high-efficiency transmission gratings fabricated in bulk fused silica for use in high-power ultraviolet laser systems. The gratings exhibit a diffraction efficiency of 94% in order m=-1 and a damage threshold greater than 13>J/cm( 2) for 3-ns pulses at 351 nm. Model calculations and experimental measurements are in good agreement. 相似文献
8.
利用波长为351 nm的半导体抽运全固态脉冲激光器,采用双光束干涉方法,对金属镍板表面直接刻蚀形成微光栅结构的方法进行了实验研究.通过改变激光功率和激光脉冲数等实验参量,研究其对制备的微光栅结构槽形和一级衍射效率的影响.利用扫描电镜和原子力显微镜测量光栅槽形,测得光栅周期为1.25 μm,光栅槽深为10~280 nm,并测量了相应的衍射效率.发现当采用激光单脉冲能量为1.2 mJ,采用10个脉冲加工时,测得槽深为280 nm,一级衍射效率最高(18%)的微光栅结构.利用光栅的衍射理论对衍射效率变化进行了分析.该研究拓展了纳秒激光在加工微结构方面的应用,为在金属材料表面制作纳米压印模版提供了一种新方法. 相似文献
9.
Holographic gratings were thermally fixed in iron-doped photorefractive LiNbO(3) crystals and developed with frequency-doubled Q -switched pulses of a Nd:YAG laser (light wavelength, 532 nm; pulse duration, 3 ns). The saturation values of the diffraction efficiency increased with increasing pulse light intensity. Compared with development with cw light, high-intensity laser pulse development resulted in an enlargement of the diffraction efficiency of a factor of ~2 . A contribution of the intrinsic defect Nb on Li site to the charge transport is most probably the origin of this effect. The results are useful, e.g., for improvements of volume holographic memories and wavelength filters. 相似文献
10.
The parameters of diffraction gratings that can be used to compress high-power femtosecond pulses of neodymium glass lasers
are analyzed based on numerical calculations. The parameters of gratings of different types are compared to evaluate prospects
for their use. 相似文献
11.
We introduce a new structural cutoff beyond which subwavelength gratings cease to behave as homogeneous media and discuss its effects on the proper selection of the sampling periods of subwavelength diffractive elements. According to this analysis, a 3lambda-period blazed binary grating composed of square pillars is designed for He-Ne operation and is fabricated by etching of a TiO>(2) layer deposited upon a glass substrate. Its first-order measured diffraction efficiency is 12% larger than the theoretical efficiency of an ideal blazed échelette grating in glass with the same period. 相似文献
12.
通过讨论超快飞秒激光脉冲和长脉冲宽度的激光脉冲紧导致宽能隙透明电介质的损伤机理和比较超短激光脉冲与长激光脉冲对宽能隙透明电介质的损伤程度,得出超短激光脉冲是一种可对透明宽带电介质进行加工的有效工具的结论。当波长为800nm,脉冲宽度为150fs的激光脉冲紧聚焦到不同的宽能隙透明电介质(K9玻璃和ZK6玻璃)体内时,可制作不同光栅常数的光栅,并在波长为635nm的He-Ne连续激光的垂直照射下,对光栅的远场相对衍射效率和光栅的衍射效率进行了测量。 相似文献
13.
Flexible gratings embedded in poly-dimethlysiloxane (PDMS) were fabricated using femtosecond laser pulses. Photo-induced gratings in a flexible PDMS plate were directly written by a high-intensity femtosecond (130 fs) Ti: Sapphire laser (λp=800 nm). Refractive index modifications with 4 μm diameters were photo-induced after irradiation of the femtosecond pulses with peak intensities of more than 1×1011 W/cm2. The graded refractive index profile was fabricated to be symmetric around the center of the focal point. The diffraction efficiency of the grating samples is measured by an He-Ne laser. The maximum value of refractive index change (Δn) in the laser-modified regions was estimated to be approximately 3.17×10−3. 相似文献
14.
Recording of holographic gratings by 532-nm laser pulses in photochromic bulk aluminosilicate glass containing silver particles is demonstrated. A diffraction efficiency of 1.5% is achieved for readout at the same wavelength. The speed of grating formation as a function of pulse energy suggests that two-photon excitation is responsible for the recording. The light causes bleaching of an absorption peak near 417nm, which corresponds to the excitation of surface plasmons on the silver, and broad darkening throughout the visible to the near infrared. A likely mechanism for the photochromic effect is discussed. 相似文献
15.
N. A. Russo R. Duchowicz J. Mora J. L. Cruz M. V. Andrs 《Optics Communications》2002,210(3-6):361-366
In this work we analyze the behavior of an erbium-doped fiber laser which is based on a simple scheme. Excitation of the active medium is performed in the 980 nm pump band with a CW semiconductor laser source. Two fiber Bragg gratings acting as mirrors of the Fabry–Perot laser cavity were used. One of these gratings was mounted over a piezoelectric (PZT) element. By applying voltage pulses to the piezoelectric, the laser cavity was temporally modulated and Q-switched laser pulses up to 530 mW peak powers at 3 kHz were obtained. Typical laser emission of 2–3 μs temporal widths and 0.1 nm of optical bandwidth have been achieved when the system was operated at 18.5 kHz repetition rates. Different behaviors were observed depending on the pumping level of the active medium and on the amplitude and frequency of the signal applied on the PZT. Q-switched laser output, in the erbium spectral gain region, with high laser efficiency of energy conversion was generated. Pumping at 76 mW and operating the laser at 18.5 kHz, an efficiency of 26% was obtained. 相似文献
16.
M. V. Ivanov S. V. Alekseev N. G. Ivanov V. F. Losev N. A. Ratakhin A. G. Yastremskii 《Bulletin of the Russian Academy of Sciences: Physics》2017,81(9):1094-1098
The results from the generation and amplification of positively chirped pulses of 0.05 ns duration at a central wavelength of 475 nm in a THL-100 laser system are presented. It is found that the initial complex allows the generation of such radiation pulses with Gaussian intensity profiles and energies of up to 7 mJ. When such pulses with energies of 2–4 mJ are amplified in an XeF(C-A) amplifier, it is possible to achieve a saturation mode and obtain at the output laser beams with energies of up to 3.2 J. The possibility of compressing subnanosecond pulses at a wavelength of 475 nm in a compressor based on diffraction gratings is demonstrated. 相似文献
17.
18.
S. N. Maximovsky A. Yu. Stavtsev V. I. Nedelkin 《Bulletin of the Lebedev Physics Institute》2017,44(12):374-379
Abstract—The interaction of pulsed laser radiation with foil-clad polycarbonate containing diffraction gratings is studied. It is found that the laser beam reflected from diffraction gratings is selffocused in polycarbonate bulk and becomes a seed for changing the polycarbonate structure, which leads to the glass transition and growth of ordered structures with symmetry features, which gives rise to the light dispersion effect in composites. A probable formation mechanism of ordered structures in polycarbonate during irradiation is proposed. 相似文献
19.
Long-period fibre gratings inside standard single-mode optical communication fibres are successfully fabricated with infrared femtosecond laser pulses. The refractive index perturbations are well confined within the fibre core by choosing the proper laser focusing parameters and translation speed of the fibre during the direct laser writing process. With the self-focusing effect considered and at a constant average irradiation dose of 1.62 × 10^3 J/(cm^2μm), the threshold intensity for fabricating long-period gratings with infrared femtosecond laser pulses is determined to be 5.13 × 10^13 W/cm2. 相似文献
20.
Generation of transient gratings in weakly absorbing liquids with a high-power laser gives rise to changes in the fluid's index of refraction that are sufficiently large to produce both multiple diffraction of a probe laser beam and a time response anomaly. The coupled-wave approach to the solution of the volume diffraction problem is shown to predict the existence of high-order diffraction of the probe beam and the time dependence of the diffraction intensity of each order. In addition, criteria for the Raman-Nath and Bragg diffraction regimes are derived from the first-order, coupled-wave equations. 相似文献