共查询到20条相似文献,搜索用时 14 毫秒
1.
Based on some numerical techniques such as split-step Fourier transformation, fourth-order Runge-Kutta and successive iteration method, the fundamental field was calculated from the known third-harmonic (TH) field in the process of TH generation (THG) using one doubling and one mixing KDP crystals. The effects of the monochromatic initial fields on the iteration numbers and the calculation precision were discussed. The inverse solution of the broadband laser pulse with linear frequency chirp was also carried out. The results show that the method proposed in this paper is available and efficient, which gives a new way to design and optimize the process of THG. 相似文献
2.
Pulse compression during second-harmonic generation in aperiodic quasi-phase-matching gratings 总被引:2,自引:0,他引:2
We propose a simple means for compressing optical pulses with second-harmonic generation. Aperiodic quasi-phase-matching gratings impart a frequency-dependent phase shift on the second-harmonic pulse relative to the fundamental pulse and can be engineered to correct for arbitrary phase distortions. The mechanism is discussed, and a detailed analysis of the compression of quadratic phase (linear frequency) chirped pulses is presented. 相似文献
3.
We describe a pulse-shaping technique that uses second-harmonic generation with Fourier synthetic quasi-phase-matching gratings. We demonstrate both amplitude and phase tailoring by generating a picosecond squarelike pulse as well as trains of femtosecond pulses with a terahertz-range repetition rate from either a compressed or a chirped pump pulse. 相似文献
4.
Y. Sheng W. Wang K. Kalinowski K. Koynov W. Krolikowski 《Applied physics. B, Lasers and optics》2011,103(1):13-16
We study parametric frequency conversion in two-dimensional nonlinear photonic crystal with short-range ordered ferroelectric
domains. We demonstrate that the short-range order enables broadband third-harmonic generation via cascading of two second-order
quasi-phase matched nonlinear processes. We obtain conversion efficiencies that are much higher than those achieved from a
randomized medium, owing to the unique distribution of reciprocal lattice vectors in the short-range ordered structure. 相似文献
5.
We demonstrate generation of two synchronized picosecond pulses at different wavelengths near 778 nm by frequency doubling of a femtosecond pulse. We use nonlinear frequency filtering with quasi-phase-matching gratings, which allow us to obtain second-harmonic spectral intensities that are higher than the spectral intensities of the pump. 相似文献
6.
《Physics letters. A》2006,349(6):484-487
Quasi-phase-matching (QPM) is an alterative approach for nonlinear optical frequency conversion compared to conventional birefringent method in the bulk crystal. In this Letter, two-dimensional aperiodic optical superlattice (2DAOS) for achieving multi-QPM is proposed. A special optical superlattice structure containing pre-designed values of the reciprocal lattice vector G that can accomplish multi-QPM process is given by using stimulated annealing (SA) algorithm. 相似文献
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We demonstrate control of the nonlinear conversion across a beam profile by using periodically poled lithium niobate with a laterally nonuniform quasi-phase-matching grating. As a representative experiment, generation of a flat-top second-harmonic beam is demonstrated. 相似文献
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10.
We demonstrate the excitation of solitons in a parametric amplifier with enhanced signal content through the use of a chirped-period quasi-phase-matching grating. This technique affords a low soliton threshold at the input end of a parametric amplifier, and the subsequent transformation to a desired soliton that exists at nonzero wave-vector mismatch through the use of a linearly chirped quasi-phase-matching grating. This approach has an advantage over direct excitation of solitons at nonzero wave-vector mismatch in uniform nonlinear materials and holds potential for improving the efficiency and mode quality of high-gain parametric amplifiers. 相似文献
11.
L.A. Golovan L.P. Kuznetsova A.B. Fedotov S.O. Konorov D.A. Sidorov-Biryukov V.Y. Timoshenko A.M. Zheltikov P.K. Kashkarov 《Applied physics. B, Lasers and optics》2003,76(4):429-433
Third-harmonic generation (THG) in reflection geometry was studied in nanostructured silicon layers grown by electrochemical
porosifying of p-type (110) silicon substrates. An order of magnitude enhancement of the THG efficiency compared to crystalline
silicon (c-Si) was observed for the samples prepared on a highly doped substrate, whereas for the samples grown on a low-doped
substrate the THG was much less efficient than for c-Si. The finding is discussed in terms of fluctuations of the electric
field of the pump-laser irradiation in the layers of anisotropically distributed silicon nanocrystals.
Received: 26 July 2002 / Revised version: 9 January 2003 / Published online: 3 April 2003
RID="*"
ID="*"Corresponding author. Fax: +7-95/939-1566, E-mail: leo@vega.phys.msu.su 相似文献
12.
Various dyes are investigated for their capability of generating 3rd harmonic of Nd-laser light. The feasibility of achieving phase matching is demonstrated by direct measurements of the index
of refraction. Third-harmonic conversion of hexamethylindocarbocyanine iodide, diethyloxacarbocyanine iodide and fuchsin red
are compared. The highest conversion is obtained for hexamethylindocarbocyanine iodide (80 times higher than in fuchsin red).
A further enhancement of the third harmonic by a factor of 70 is expected for the fundamental laser light at 1.15 μm. 相似文献
13.
It is shown that two-photon-resonant tripling of the ruby laser frequency in cesium vapor is limited by ionization. The laser induced Stark shift is found to be favorable to the process in that it counteracts saturation of the resonant transition. 相似文献
14.
The third-harmonic generation of picosecond light pulses in a calcite crystal is studied experimentally and theoretically. A passively mode-locked Nd: phosphate glass laser is used in the experiments. The third-order nonlinear susceptibility components and the effective third-order nonlinear susceptibility of type II phase-matched (ooee) thirdharmodic generation are determined.On leave from Shanghai Institute of Optics and Fine Mechanics, Academia Sinica, Shanghai, P.R. China 相似文献
15.
We characterize experimentally the influence of sample structure and beam focusing on signal level in third-harmonic generation (THG) microscopy. In the case of a homogeneous spherical sample, the dependence of the signal on the size of the sphere can be controlled by modifying the Rayleigh length of the excitation beam. More generally, the influence of excitation focusing on the signal depends on sample geometry, allowing one to highlight certain structures within a complex system. We illustrate this point by focusing-based contrast modulation in THG images of Drosophila embryos. 相似文献
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We demonstrate the generation of sub-6-fs pulses centered at 405 nm by frequency doubling of 8.6-fs Ti:sapphire laser pulses. The frequency doubling is carried out in a nonlinearly chirped quasi-phase-matching grating fabricated in a lithium tantalate substrate. This device simultaneously provides frequency conversion and pulse compression of the positively prechirped fundamental pulses. The second-harmonic pulses are characterized in a cross-correlation setup, and their pulse shapes are retrieved by two iterative phase-reconstruction algorithms. The generated second-harmonic spectrum spans a bandwidth of 220 THz. To our knowledge, these are the shortest pulses ever generated in the blue spectral region. 相似文献
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19.
Phase-matched third-harmonic generation is demonstrated in a germanium-doped optical fiber. Green light at 514.4 nm is generated in an LP(03) mode when a pump field at ~1543.3 nm is launched into the fiber in the fundamental LP(01) mode. The phase matching is achieved for a particular combination of the germanium doping concentration and the fiber core diameter. 相似文献
20.
A method for measuring resonances using a combination of third-harmonic generation and frequency-domain interferometry is described and demonstrated in an index-matched dielectric material. The phase of the third-harmonic spectrum of a pulse generated from a resonant NdAlO(3) thin film and a temporally displaced sapphire substrate pulse was measured by analyzing the spectral interference pattern. The appropriate combination of substrate and film signals was obtained by translating the sample through the laser focus while observing the third-harmonic intensity. 相似文献