Ⅰ类非临界相位匹配LBO腔外倍频660nm效率的研究

报道了利用LBO晶体对Nd:YAG纳秒激光器进行腔外倍频实验的研究结果,实验中LBO晶体采用Ⅰ类非临界相位匹配(NCPM),温度调谐。实验证明,采用LBO温度调谐方式具有倍频效率高、稳定性好、易于调节等优点,当匹配温度为8.4℃、基频光功率为1.3J时,获得了855mJ的660nm倍频光输出,最高转换效率达到66%,倍频光能量稳定度小于±3%。     

BIBO晶体非临界相位匹配的研究

为了研究BIBO晶体的非临界相位匹配的特点及应用,采用MATLAB编程的精确计算方法,在BIBO的热光色散方程的基础上,以波长为532nm的绿光作为抽运光,计算了BIBO在非临界相位匹配下的温度调谐、有效非线性系数和允许参量。计算得出,当匹配角θ=90°时,信号光的温度调谐范围为0.65μm~3.0μm;当信号光波长为670nm时,BIBO的差频Ⅱ类(B)相位匹配的最佳匹配条件为:Tm=22.3℃,φ=35°,deff=1.904pm/V。结果表明,BIBO的非临界相位匹配有望应用于激光电视等可见波段激光产品。     

非临界相位匹配KTP光学参量振荡器的研究

利用1. 06μm激光脉冲泵浦非临界相位匹配(NCPM) KTP光学参量振荡器,获得中心波长1566nm的信号光输出。当泵浦光能量为100mJ时,输出信号光能量约为31. 9mJ ,相应的转换效率为30. 9% ,信号光脉冲宽度(10ns)比泵浦光脉冲宽度(30ns)小得多。当相位匹配角(内角)从90°到80°变化时,信号光调谐范围为1566～1596nm。     

GdYCOB的生长及非临界相位匹配三倍频性质

在大气气氛下生长了高光学质量的晶体Gd0.37Y0.63Ga4O(BO3)3(GdYCOB);测量了GdYCOB晶体的非晶界相位匹配三倍频转换效率,分析了GdYCOB晶体中色心等缺陷对三倍频转换效率的影响并提出了消除色心的途径。     

基于腔相位匹配差频产生太赫兹的研究

研究了基于GaAs晶体的腔相位匹配(CPM)差频产生太赫兹的过程,得出太赫兹波长与最优腔长之间的关系,并结合温度对太赫兹波长的影响,可实现太赫兹波段范围内的连续调谐输出。当泵浦光在微腔中往返20次时,腔相位匹配产生太赫兹的功率转换效率可达1.33%,在效率相同的情况下,CPM腔长为581.41 μm时相当于准相位匹配(QPM)条件下的晶体长度约23 mm。可以预见由腔相位匹配原理制备的太赫兹源将具有广阔的应用前景,该结果对相关实验具有一定的参考价值。     

基于差频产生太赫兹的中远红外非线性光学晶体

文章介绍了ZnGeP2,GaSe,CdSe,GaAs,GaP,DAST等几种用于太赫兹辐射的中远红外非线性光学晶体的非线性性能,总结了利用它们通过非线性光学差频产生太赫兹方面的最近进展.最后给出了获得较高转换效率和能量的太赫兹波输出的非线性光学晶体应具备的条件.     

近非临界相位匹配温度调谐MgO：LiNbO3OPO

通过对MgO:LiNbO3参量过程温度相位匹配及走离角，允许参量等运转参数的理论计算与分析，确定了晶体的切割角度θ=82℃，以近非临界相位匹配（NCPM）取代NCPM，将温度调节范围控制在较低的温度上，研制了532nm泵浦的MgO:LiNbO3温度调谐脉冲光学参数振荡器（OPO），在800～1700nm波段实现连续调谐输出。参量泵浦功率密度阈值为57.3MW/cm^2，泵浦能量约2倍阈值处，单谐振（SRO）参量转换效率为11%以上。     

高掺镁铌酸锂晶体的临界和非临界相位匹配条件

基于掺5%克分子MgO的LiNbO3晶体主折射率及温度系数的精确测量,计算了这种晶体的临界和非临界相位匹配条件,计算结果经实验验证,二者相当一致。     

临界相位匹配砷酸钛氧钾光参量振荡器研究

为得到3~5 μm的中红外输出,对非共线泵浦砷酸钛氧钾（KTA）的临界相位匹配（θ=41.4°,φ=0°）光参量振荡器（OPO）进行了理论分析及实验研究。当以电光调Q的Nd∶YAG激光器泵浦KTA-OPO时,对应输出为3.75 μm的中红外激光,重复频率为1~25 Hz,最高输出单脉冲闲频光能量≥4.5 mJ。     

高效率非临界相位匹配KTP光学参量振荡器

利用Nd∶YAG激光器1．064μm基频光抽运非临界相位匹配KTP（θ＝90°,＝0°）光学参量振荡器（OPO）,获得1．57μm相干光和高达64％的能量转换效率,分析了非临界相位匹配方式对KTP晶体定离效应和接收角的影响,并对OPO的阈值、效率、输出的光束质量进行了讨论。     

Difference-frequency generation in a butt-join diode laser

The intracavity difference-frequency generation in the middle-infrared region in the GaAs/InGaAs/InGaP butt-join diode lasers with quantum wells is experimentally studied.     

All-optical transistor action by polarisation rotation duringtype-II phase-matched second harmonic generation

Intensity dependent polarisation rotation of the field at the fundamental wavelength in a type-II phase-matched frequency-doubling crystal is used for optical signal amplification. A gain of more than 21 dB was experimentally obtained using KTP for the nonlinear material     

Theory on phase-matched second-harmonic generation in biaxialplanar waveguides

A theoretical study on the optimization of second harmonic generation (SHG) in a planar waveguide in a biaxial nonlinear material is presented. Numerically computed curves show the dependence of the SHG efficiency on the condition of lateral focusing in the planar waveguide, of double refraction and of phase matching. The calculations take full account of double refraction and diffraction in the paraxial approximation in the planar guide. It is shown that in the absence of double refraction and under optimum focusing conditions the generated second harmonic power increases in proportion to L^3/2, where L is the length of the planar waveguide     

Efficient phase-matched second-harmonic generation and sum-frequency mixing in urea

The performance of urea as a new nonlinear optical crystal for phase-matched second-harmonic generation and sum-frequency mixing in the UV is reported. Tunable radiation down to 229 nm was obtained. In particular, efficient doubling at room temperature of CW argon laser lines from 488 to 528 nm was achieved. The nonlinear coefficient of urea was measured and found to be 2.5 times that of ADP. Angle tuning curves for type II SHG, several type II frequency mixing schemes, temperature tuning data, and comparison to other nonlinear materials are presented. More accurate Sellmeier constants were also obtained using the measured angle tuning curve for type I SHG.     

Second harmonic generation in 90º phase-matched KDP isomorphs

Experimentally determined 90° phase-matching temperatures, as a function of optical wavelength, for second harmonic generation in a number of KDP isomorphs are discussed. The data are applicable for SHG of tunable dye laser radiation to cover the UV spectral range of about 260-360 nm.     

Nearly noncritically phase-matched UV generation at 3547 Å in NaCHO2

Sodium formate (NaCHO2) has been found to be very nearly noncritically phase matchable for type-2 frequency mixing of the Nd:YAG laser fundamental and second-harmonic radiation at room temperature. The nonlinear optical constant was determined to be d32(NaCHO2) =(1.25 pm 0.25) times 10^{-9}ESU.     

A new detection technique of gas concentration with optical spectrum absorption at near-IR wavelength

Wavelength modulation technique(WMT) and active intracavity technique(ACIT) are first introduced in this paper,which are used to realize the concentration detection of methane and acetylene respectively.When ACIT is combined with wavelength sweep technique(WST),the detection sensitivity of acetylene can be enhanced sharply.When ACIT is combined with WST and WMT,the detection sensitivity of acetylene can be enhanced further.     

Picosecond ultraviolet optical parametric generation using atype-II phase-matched lithium triborate crystal for an injection seed ofVUV lasers

Output performance of a type-II phase-matched optical parametric generator using lithium triborate pumped at 266 nm is investigated. The optical parametric generator is designed to produce a narrow linewidth signal with good spatial quality at 326.7 nm for application to injection seeding of a vacuum ultraviolet (VUV) plasma laser. A linewidth of less than 0.1 nm and a beam divergence of 2× diffraction limit have been achieved without any diffractive optics     

Step-repeat pattern generation technique

A simple technique of generating step - repeat patterns of wide area fine geometry devices, e.g. S.A. W. Colour TVI.F. filter on the wafer by using the single pattern photomask is described. The various advantages of the technique are also pointed out.     

A simple instrument and technique for measuring columnar watervapor via near-IR differential solar transmission measurements

A simple two-channel solar radiometer and data retrieval technique is described for sensing the columnar content of atmospheric water vapor via differential solar transmission measurements in and adjacent to the 940-nm water vapor absorption band. The instrument features two parallel channels for simultaneous measurements in and out of the absorption band to eliminate temporal variability effects in the differential comparison of the data from the two channels. The water vapor transmittance is determined by a modified Langley plot analysis of the ratio of the two channel signals. A statistical band model which closely follows the square-root law is then used to extract the columnar water vapor amount from the water vapor band transmittance. Error analyses and experimental results indicate that the instrument/technique can be reasonably employed to retrieve water vapor amounts with an error of 10% or less