共查询到20条相似文献,搜索用时 15 毫秒
1.
Tunable cw infrared radiation has been generated by non-collinear difference-frequency mixing in LiJO3, using the intracavity radiation of a Nd:YAG laser and the output of a Rhodamine 6G dye laser. Infrared powers of ∽35 μW tunable from 1.28 μm to 1.62 μm have been obtained. 相似文献
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XiaoChun Mei 《中国科学G辑(英文版)》2008,51(3):282-298
It has been proved that when the retarded effect (or multiple moment effect) of radiation fields is taken into account, the
high order stimulated radiation and stimulated absorption probabilities of light are not the same so that time reversal symmetry
would be violated, though the Hamiltonian of electromagnetic interaction is still unchanged under time reversal. The reason
to cause time reversal symmetry violation is that certain filial or partial transition processes of bound atoms are forbidden
or cannot be achieved due to the law of energy conservation and the special states of atoms themselves. These restrictions
would cause the symmetry violation of time reversal of other filial or partial transition processes which can be actualized
really. The symmetry violation is also relative to the asymmetry of initial states of bound atoms before and after time reversal.
For the electromagnetic interaction between non-bound atoms and radiation field, there is no such kind of symmetry violation
of time reversal. In this way, the current formula on the parameters of stimulated radiation and absorption of light with
time reversal symmetry should be revised. A more reliable foundation can be established for the theories of laser and nonlinear
optics in which non-equilibrium processes are involved. 相似文献
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U. Chatterjee P. Kumbhakar A.K. Chaudhary G.C. Bhar 《Applied physics. B, Lasers and optics》2001,72(4):407-409
Non-collinear difference frequency mixing is reported for the first time in a lithium tetraborate (Li2B4O7) crystal, and is used to generate near-infrared radiation in the range 1700–2300 nm.
Received: 13 July 2000 / Published online: 10 January 2001 相似文献
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G. G. Denisov A. V. Smorgonsky V. P. Gubanov S. D. Korovin V. V. Rostov M. I. Yalandin 《International Journal of Infrared and Millimeter Waves》1984,5(10):1389-1403
The stimulated scattering of electromagnetic waves in microwave generators, in which a high-current electron beam excites either a backward wave (BWO) or a quasi-critical frequency wave (orotron) is investigated experimentally. The scattering occurs at the same electron beam and the high-frequency feedback is provided by the inhomogeneities of the electrodynamic system of the microwave generator itself. A power of several tens of megawatts has been achieved in the 3-mm range. The mode selection permitted to obtain single-mode scattering. 相似文献
6.
We observed tunable UV radiation down to 175 nm by SRS of the output of a frequency-doubled dye laser in H2. The high power output of the 4th anti-Stokes to 5th Stokes line generated by the frequency doubled dye laser and the 8th
anti-Stokes to 3rd Stokes line generated by the undoubled dye laser represents a broadly tunable coherent radiation source
between 189 nm and 2064 nm. 相似文献
7.
We report on the generation of tunable, narrow-band picosecond laser pulses in the mid-IR at 1 kHz repetition rate. An optical parametric oscillator (OPO) seeded optical parametric amplifier (OPA) delivers signal and idler pulses with energies of several hundred microjoule tunable between 1.56 and 3.24 m. Difference frequency mixing of the OPA signal and idler waves permits the generation of mid-IR radiation between 3 and 24 m. The laser system therefore permits full coverage of the wavelength range between 1.6 and 24 m. Conversion efficiencies greater than 50% and pulse energies up to 40 J are obtained with GaSe. PACS 42.65.Re; 42.65.Yj; 42.72.Ai 相似文献
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O. Arimoto M. Watanabe T. Tsujibayashi J. Azuma M. Kamada S. Nakanishi H. Itoh M. Itoh 《Radiation measurements》2010,45(3-6):356-358
Production of radiation defects in a widely used scintillation material BaF2 has been studied by means of a combination spectroscopy of synchrotron radiation (SR) and laser, in which defects produced by SR irradiation are sensitively detected by observing the luminescence stimulated by laser light. The photostimulated luminescence arises from the recombination of self-trapped holes (VK centers) with electrons released from trapped centers by laser light. The obtained result reveals that the production efficiency of radiation defects is drastically dependent on the excitation photon energy of valence or core excitons. 相似文献
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Extending our work on the enhancement of photon antibunching we investigate the photon statistics after interference of a two-photon absorbed beam with a coherent one. The interference is calculated in the polarization picture but the equivalence to an interferometer is shown. We use the asymptotic behaviour during two-photon absorption and apply also approximate equations to study the system in the time domain before the asymptotic regime is reached. 相似文献
10.
Far-infrared radiation tunable over the range 85–105 cm-1 and at power levels of up to 10 μW has been generated by difference frequency mixing in InSb. The infra-red radiations which are mixed are a 10.6 μm TEA-CO2 laser line and the tunable Stokes radiation produced from it by spin-flip Raman-laser action, again in an InSb sample. It is argued that careful choice of the free-carrier concentrations in the crystals used for (a) the Stokes generation and (b) the mixing, or the application of an electric field across the mixing sample, should considerably improve the far-infrared power levels. 相似文献
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In this paper measurements of the frequency, linewidth and polarization of stimulated recombination radiation (SRR) fromp-type InSb are reported. The samples had low excess-carrier concentrations between 1014 and 1015 per cm3 and different lengths between 0.4 and 9 mm. They were held in magnetic fields up to 6T at temperatures of pumped liquid helium. The excitation was done optically by the radiation of a Q-switched CO-laser. We could observe a number of different stimulated processes:
- band-to-band recombination (tuning between 1875 and 1980 cm?1),
- band-to-acceptor recombination (tuning between 1840 and 1930 cm?1),
- stimulated spin-flip Raman scattering (SFR) of the SRR by excited electrons,
- SFR of the laser by excited electrons and its interaction with the SRR.
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A theory is presented for the induced decay of isomer levels for nuclei exposed to a laser field, which couples the initial isomer level to intermediate higher lying levels with short lifetimes. We took into account the electric dipole transitions between these levels in a one-photon approximation. The time-dependent Schrödinger equation with a periodic Hamiltonian is solved by the method of the composite Hilbert space. A simple expression for the broadening of the isomer level ΔΓ, caused by the laser radiation, is derived. As an example, we considered the decay of the isomer level 970.17 keV with the spin I π = 23/2? of 177Lu, coupled by the laser wave to the virtual level 1352.33 keV with I π = 21/2+. The ratio of the broadening ΔΓ to the natural width of the isomer level Γ is found to be about 40% for a 1017 W/cm2 laser. Any influence of the electronic environment is not taken into account. 相似文献
14.
为研究超高速碰撞产生闪光的辐射演化特征,利用建立的瞬态光纤高温计测量系统结合二级轻气炮加载系统,进行了4种实验条件下的超高速碰撞实验。每组实验使用一组光纤探头,基于实验所获原始数据结合标定,通过Matlab编程处理得到了给定实验条件及光纤探头安装方案条件下的闪光强度演化,利用比率法得到碰撞闪光的辐射温度演化特征。实验结果表明,在488~667 nm波长范围内超高速碰撞LY12铝靶产生的闪光强度与辐射温度峰值随碰撞角度(与靶板平面的夹角)的增大而减小。 相似文献
15.
P. Martin A. Belsky E. Constant E. Mevel A. Philippov V. Strelkov 《Applied physics. B, Lasers and optics》2004,78(7-8):1005-1008
The project of set-up for time resolved femtosecond VUV spectroscopy, which is based on a high harmonic generation source and a VUV monochromator is presented. We discuss the generation conditions of quasi-continuous VUV spectrum via HHG in Ar using the intense chirped IR fundamental pulse and the relatively weak second harmonic of IR fundamental. The desired narrow VUV spectral range is selected by time compensated double monochromator with concave spherical diffraction gratings. PACS 42.65.Ky; 42.79.Dj; 78.47.+p; 39.30.+w 相似文献
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The acoustic wave propagation from a two-dimensional subwavelength slit surrounded by metal plates decorated with Helmholtz resonators(HRs) is investigated both numerically and experimentally in this work. Owing to the presence of HRs, the effective impedance of metal surface boundary can be manipulated. By optimizing the distribution of HRs,the asymmetric effective impedance boundary will be obtained, which contributes to generating tunable acoustic radiation pattern such as directional acoustic beaming. These dipole-like radiation patterns have high radiation efficiency, no fingerprint of sidelobes, and a wide tunable range of the radiation pattern directivity angle which can be steered by the spatial displacements of HRs. 相似文献
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Transient stimulated Raman scattering (TSRS) of picosecond dye laser pulses in ethanol has been investigated experimentally. In particular some temporal features of TSRS from the C-H stretching mode (2928 cm-1) in ethanol have been studied with a Photochron II streak camera with subpicosecond time resolution. It is shown that the use of TSRS provides a simple method for producing picosecond pulses tunable over the spectral region ≈492–532 nm and 691–772 nm by tuning a passively mode-locked Rhodamine 6G dye laser from 575–630 nm. 相似文献