共查询到20条相似文献,搜索用时 109 毫秒
1.
从实验上证实Hg0.695Cd0.305Te 光电二极管空间电荷区中存在双光子吸收的Franz-Keldysh效应.利用一个皮秒Nd:YAG激光器抽运的光学参量产生器和差频产生器作为激发光源,测量了入射波长为λ0=7.92μm的脉冲激光所激发的光响应随入射光强的变化关系.脉冲光响应峰值强度随入射光强的增大呈现二次幂函数增强趋势.采用等效RC电路模型将脉冲光伏信号峰值与入射光强相关联,得到空间电荷区中强电场下单光束 相似文献
2.
以半经典密度矩阵理论和分子振动弛豫理论为基础,研究添加适当比例缓冲气体与适当减小波导芯径对光抽运太赫兹激光器输出光强的影响.计算结果表明,加入适当比例缓冲气体或适当减小波导的芯径均能提高太赫兹激光的输出光强;同时优化两个参数能进一步提高抽运激光能量转化为太赫兹激光能量的效率,延长工作腔中的有效激活区,延缓抽运饱和效应的出现,提高太赫兹激光输出光强.该研究对提高光抽运太赫兹激光器的能量转化效率、提高光抽运太赫兹激光器的输出功率及实现光抽运太赫兹激光器的小型化有重要的指导意义. 相似文献
3.
4.
为了获得较窄增益带宽、较大光强的太赫兹辐射,尝试了利用TEA CO2激光器对6 W可调谐连续波CO2种子激光实行双程光放大实验,以期望获得长脉冲、高峰值功率的抽运光.通过实验,获得了大约30倍的放大系数,放大光输出功率随种子光注入功率的增加而增加,其中10 P (20)支线表现更加突出,并且被放大的激光支线半峰全宽在14 μs左右.基于这种长脉冲抽运源,建立了一种产生脉冲太赫兹的动力学模型,给出了产生太赫兹辐射的饱和抽运光强表达式,确定了抽运光的光强范围.另外,
关键词:
激光物理
长脉冲
动力学模型
太赫兹激光 相似文献
5.
6.
7.
8.
利用半经典理论,对脉冲光学抽运重水气体产生THz激光信号过程进行分析,对其中抽运光强度与输出THz信号光之间的关系进行了数值计算和求解,结果表明,THz信号出射光强度跟抽运源入射光强度之间不满足简单的线性关系,而是呈现高阶的非线性关系.在工作介质腔长、气压和工作温度一定的条件下,存在最佳抽运光强度,在一定的抽运光强范围内,THz信号出射光强度与抽运源入射光强度的关系呈现近似线性的增长关系,抽运光能量和信号光能量之间的转换效率相对较高,当抽运光强超过一定值时,由于瓶颈效应的发生会导致THz输出信号的逐步减弱,并产生一定的频率调谐范围. 相似文献
9.
利用激光与等离子体相互作用产生超强太赫兹辐射的研究成为国内外研究的热点。基于Smith提出的线形天线辐射理论,对超强超短激光脉冲驱动天线靶产生太赫兹的辐射特性进行研究,建立了完备的辐射空间分布和频谱空间分布表达式。利用激光脉冲长度与天线长度的比值对辐射场分布的影响,讨论了固定天线长度时的最佳激光脉冲长度,以及固定激光条件时,天线长度对辐射场的频谱和空间分布的调制作用。理论分析结果表明,激光脉冲长度决定了辐射频率范围,激光脉冲长度与天线长度的比值决定了辐射场峰值的方向和频谱分布,为设计合理实验方案提供理论依据。 相似文献
10.
搭建了飞秒时间分辨受激拉曼光谱(FSRS)装置,并用于研究全反式β-胡萝卜素单重电子激发态超快内转换和振动弛豫过程.基于三脉冲“抽运-探测”方案搭建的时间分辨受激拉曼光谱装置同时实现了150fs的时间分辨率和23.7cm-1的光谱分辨率,光谱检测范围为300—4000cm-1.对全反式β-胡萝卜素电子激发态的飞秒时间分辨拉曼光谱研究表明,β-胡萝卜素被激发到S2态后,经由寿命约为0.3ps的中间态SX态实 相似文献
11.
采用中频感应提拉法生长了高质量的Tm:Y2SiO5(Tm:YSO)晶体,测定了晶体的晶格常数和分凝系数.运用劳厄照相法确定了单斜晶系Tm:YSO晶体的三个偏振轴〈010〉,D1和D2,在室温下测量了三个偏振轴方向的吸收光谱、荧光光谱和荧光寿命,计算了晶体吸收峰的吸收线宽和吸收截面.研究发现,相对于其他两个偏振轴方向,D1方向在790nm处出现较强的吸收峰,
关键词:
2SiO5')" href="#">Tm:Y2SiO5
单斜晶系
吸收光谱
荧光光谱 相似文献
12.
We report the preparation of D2 molecules in v=2 level in molecular beam condition. A single longitudinal mode laser system was used for excitation of D2 from (v=0, j=0) to (v=2, j=0) with the scheme of stimulated Raman pumping. An excitation efficiency of 25.2% has been achieved, which was determined by the scheme of resonance-enhanced multiphoton ionization. Dependence of relative excitation efficiency on laser energy has been measured. We found that the increasing rate of excitation efficiency became slower as pulse energy of Stokes laser increase, while the excitation efficiency still increases approximately linearly with pump pulse energies up to 60 mJ. The spectral line shapes of Raman transition was also measured at different laser energies and considerable dynamical Stark effect was observed. A single peak was found on the three dimension surface of relative excitation efficiency, indicating the process occurred in the present study is a process of stimulated Raman pumping instead of stimulated adiabatic Raman passage. 相似文献
13.
Xiao Huang Xizhang Luo Xun Zhang 《International Journal of Infrared and Millimeter Waves》2001,22(1):31-39
By means of solving the density matrix equations, base on the mechanism model of buffer gas, the output intensity of FIR and the FIR signal gain coefficient Gs and IR pumping signal absorption coefficient Gp were calculated, energy exchanged process of superradiant OPFIRL with buffer gas was analyzed. It was found that after adding buffer gas into the laser medium, the FIR output could be increased, and the active region of a FIR laser was lengthened. 相似文献
14.
Lijie Geng Zhifeng Zhang Yusheng Zhai Yuling Su Fanghua Zhou Kuan Zhu Yanchen Qu Weijiang Zhao 《Journal of Russian Laser Research》2017,38(4):392-397
We report on the mid-infrared (MIR) and terahertz (THz) wave spectra of D2O gas pumped using a fundamental transverse mode transversely excited atmospheric CO2 laser with an emission wavelength of 9.26 μm. We obtain MIR emission lines at center wavelengths of 9.262, 9.491, and 9.752 μm, which correspond to the vibrational-energy-level-transition lines of D2O. We observe an intense THz stimulated Raman emission line of 385 μm and a weak cascade-transition line of 359 μm for transitions from rotational levels 422 to 413 and 413 to 404 in the first-excited vibration state of the D2O molecule gas. We establish a four-energy-level system for modeling the laser kinetics of the dual-wavelength (385 and 359 μm) superradiation THz laser. For the optically pumped D2O gas 385 μm THz laser, in considering the cavity effect and insertion loss of a THz cavity oscillator, an approximation treatment of the THz laser kinetics can be made based on a three-energy-level system. 相似文献
15.
16.
Xiao Huang Yanxiang Bao Xizhang Luo 《International Journal of Infrared and Millimeter Waves》2004,25(2):247-256
In an optically pumped far-infrared laser (OPFIRL) system, the infrared (IR) pumping laser with collision broadening which was closer to the practice was considered. A more precise mathematical model was set up. When the IR pumping laser line had the Lorentz function structure, by solving the semi-classic density matrix equations, the generalized form of FIR signal gain Gs and IR pumping signal absorption coefficient Gp were obtained. 相似文献
17.
Koo Hendrik Kurniawan 《应用光谱学评论》2013,48(2):99-130
Abstract Hydrogen emission in laser plasma has been studied by focusing a TEA CO2 laser and Nd‐YAG lasers on various types of samples, such as glass, quartz, and zircaloy pipes doped with hydrogen. It was found that Hα emission with a narrow spectral width occurs with high efficiency when the laser plasma is produced in low‐pressure host gas. In contrast, the conventional well‐known laser‐induced breakdown spectroscopy (LIBS), which operates at atmospheric air pressure, cannot be applied for the analysis of hydrogen as impurity. The specific characteristic of hydrogen emission in low‐pressure plasma is interpreted on the basis of our shock wave model, taking account of the fact that the hydrogen mass is extremely light compared to that of the host target. Another experimental study on gas analysis was conducted using an Nd‐YAG laser and helium host gas at atmospheric pressure on a sample of mixed water (H2O) and heavy water (D2O) in vapor form. It was shown that completely resolved hydrogen (Hα) and deuterium (Dα) emission lines that are separated by only 0.179 nm could be obtained at a properly delayed detection time when the charged particles responsible for the strong Stark broadening effect in the plasma have mostly disappeared. It is argued that a helium metastable excited state plays the important role in the hydrogen excitation process. 相似文献
18.
T. Okada S. Inoue T. Ohga K. Muraoka M. Akazaki 《International Journal of Infrared and Millimeter Waves》1985,6(9):883-892
A D2O laser has been developed for collective Thomson scattering measurements of ion temperature in high temperature plasmas. A pulse duration and a spectral width of a high power D2O laser has been successfully controlled for this purpose, by using a TEA CO2 laser injection-locked by an etalon-tuned TEA CO2 laser as a pump source. 相似文献
19.
K. Sasaki O. Takahashi N. Takada M. Nagatsu T. Tsukishima T. Okada S. Okajima Y. Tsunawaki S. Sudo K. N. Sato et al. 《International Journal of Infrared and Millimeter Waves》1995,16(12):2133-2146
Spectrally narrow, pulsed outputs consisting of almost a single mode have been obtained from an optically-pumped high-power (200kW) D2O laser by adopting the injection seeding method, where single-mode radiation (seed pulse) from a low-power, compact D2O laser has been injected into the main D2O laser. Spectrally narrow outputs with high power having spectral widths as narrow as 5 MHz have been obtained, when the seed pulses with frequency tuned to one longitudinal mode of the main D2O laser have been injected at a time sufficiently before the lasing of the main laser took place. The experimental results have been compared with those of numerical simulation modified to include the injection field with varying injection times. 相似文献
20.
Various criteria for designing high power convective cooled CO2 lasers have been discussed. Considering the saturation intensity, optical damage threshold of the optical resonator components
and the small-signal gain, the scaling laws for designing high power CW CO2 lasers have been established. In transverse flow CO2 lasers having discharge of square cross-section, the discharge lengthL and its widthW for a specific laser powerP (Watt) and gas flow velocityV (cm/s) can be given byL = 1.4 x 104
p
1/2
V
-1 cms andW = 0.04P
1/2 cms.
The optimum transmitivity of the output coupler is found to be almost constant (about 60%), independent of the small signal
gain and laser power. In fast axial flow CO2 lasers the gas flow should be divided into several discharge tubes to maintain the flow velocity within sonic limit. The
discharge length in this type of laser does not depend explicitly on the laser power, instead it depends on the input power
density in the discharge and the gas flow velocity. Various considerations for ensuring better laser beam quality are also
discussed. 相似文献