LD泵浦Nd:YVO4/LBO临界相位匹配腔内倍频瓦级绿光激光器

报道了一种光纤耦合LD泵浦Nd:YVO₄晶体、腔内Ⅰ类临界相位匹配(角度匹配)LBO倍频、瓦级输出的全固态绿光激光器的设计方法和实验结果.采用短三镜折叠腔结构,通过对热透镜焦距的估算及计算机优化设计选取合适的谐振腔参量,在8 W的泵浦功率下,获得了1.6 W绿光基模输出,光-光转换效率达20%.经测量,绿光的偏振比超过400:1,4 h功率稳定度为±1.6%.     

串联双环光微谐振器的滤波特性

详细研究了串联双环光微谐振器的光带通滤波特性，给出了其通带带宽的公式，分析了出／入环光耦合系数和环间光耦合系数对通带特性的影响，计算并特别强调了滤波通带的结构特点，也分析了微环中存在的光损耗对串联双环光微谐振器的滤波特性的影响。     

基于NbN，AIN技术的体声波器件研究

体声波滤波器由于其低插损、小尺寸、高带外抑制等特性，随着第三代移动通信以及蓝牙技术的发展而得到广泛研究，而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能．我们以单晶MgO作为器件衬底，MgO/NbN多层结构作为AIN薄膜体声波器件的反射器，NBN／AIN／NbN三层结构为谐振器．在这样的多层结构的设计中由于各种材料之间的晶格失配小，可以获得从几十纳米到几百纳米厚度不等的单晶AIN薄膜．通过控制AIN薄膜和NbN薄膜的不同厚度，可以获得不同频段范围的谐振器．压电薄膜的质量，以及体声波在多层结构界面上的能量损耗，直接影响到谐振器电学性能．基于AIN材料的压电性能，设计了NBN／AIN／NBN三层结构的谐振器，并进行了数值模拟．     

1064nm纳秒激光脉冲激发的外腔式PbWO4拉曼激光器

研究了外腔式PbWO4拉曼激光器在纳秒脉冲抽运下的输出特性。利用主动调Q的Nd:YAG激光器产生的脉冲宽度为31.4ns,最大输出能量为200mJ的1064nm激光作为抽运源。拉曼激光谐振腔采用的是平凹腔设计。测量了输出的拉曼光脉宽与抽运能量的关系,分析了输出的拉曼光脉冲波形图和光谱图,测量了输出的拉曼光脉冲能量与抽运能量的关系,计算了转换效率与抽运能量的关系。当注入抽运光能量达到42mJ时,得到了一阶斯托克斯光脉冲的最大能量和转换效率分别为10mJ和24%,获得外腔式PbWO4拉曼激光器的一阶斯托克斯光脉冲波长为1177.6nm,典型的一阶斯托克斯光脉冲脉宽为20ns。     

One-Step Generation of Multi-Qubit GHZ and W States in Superconducting Transmon Qubit System

We propose a one-step method to prepare multi-qubit GHZ and W states with transmon qubits capacitively coupled to a superconducting transmission line resonator(TLR).Compared with the scheme firstly introduced by Wang et al.[Phys.Rev.B 81(2010) 104524],our schemes have longer dephasing time and much shorter operation time because the transmon qubits we used are not only more robust to the decoherence and the unavoidable parameter variations,but also have much stronger coupling constant with TLR.Based on the favourable properties of transmons and TLR,our method is more feasible in experiment.     

Multi-qubit controlled-NOT gates and Greenberger–Horne–Zeilinger state generation using one qubit simultaneously controlling n qubits

Based on superconducting flux qubits coupled to a superconducting resonator. We propose a scheme for implementing multi-qubit controlled-NOT (C-NOT) gates and Greenberger–Horne–Zeilinger (GHZ) state with one flux qubit simultaneously controlling on n qubits. It is shown that the resonator mode is initially in the vacuum state, a high fidelity for operation procedure can be obtained. In addition, the gate operation time is independent of the number of the qubits, and can be controlled by adjusting detuning and coupling strengths. We also analyze the experimental feasibility that the conditions of the large detuning can be achieved by adjusting frequencies of the resonator and pulses.     

Improvement of the MEMS bionic vector hydrophone

A kind of MEMS vector hydrophone with bionics structure was introduced in 2007. As the acoustic-electric transducer structure and the acoustic package of hydrophone have been optimized, the performance of the hydrophone has been greatly improved compared with the previous. This hydrophone calibration was completed in the National Defense Underwater Acoustics Calibration Laboratory of China. According to the test results, the sensitivity of the hydrophone is −165 dB (including pre-amplification 20 dB), the frequency response ranges from 20 Hz to 2 kHz (±5 dB), and this hydrophone has a good directional pattern in the form of “8”-shape.     

一种新的平面回音壁模蓝宝石谐振器模型

基于环状谐振器传输线法(Transmission-line ring resonator)分析建立了单端口和双端口回音壁模平面蓝宝石介质谐振器模型,分别得到了对应的传输公式。并设计制作了一个单端口蓝宝石谐振器,采用新模型可以对原先模型一直无法解释的实验现象作出合理的解释,验证了该模型的有效性。     

Precision Resonator Microwave Spectroscopy in Millimeter and Submillimeter Range

By the use of Fabry–Perot resonator with quality factor 600 000 and fast precision (down to one Hertz) frequency control of coherent millimeterwave radiation source the 20 Hz accuracy in measurements of the width of resonance curve is obtained. This accuracy corresponds to the detection of 1.8 × 10^–3 dB/km absorption in the sample filling the resonator and exceeds the before known sensitivity more than by an order of magnitude. The example of precise measurement of 60 GHz oxygen absorption band in the real atmosphere is presented. The new possibilities of application of precision resonator microwave spectroscopy to the atmospheric problems as well as to the ultra-low absorptions measurements in dielectrics and metal surfaces up to Terahertz frequencies are discussed.     

Astigmatism of the radiation of semiconductor stripe-geometry lasers

The effect of injection current on the intensity and angular distribution of radiation in TE- and TM-polarized modes of diode lasers with a stripe geometry and double GaAs-AlGaAs-based heterostructure is investigated. The analysis of the angular distribution of radiation revealed the nonmonotonic behavior of its astigmatism with increase in the current. The coefficient of astigmatism in the mode of lasing is substantially higher for the TE-mode than for the TM-mode. An increase in radiation astigmatism is accompanied by a decrease in the differential effectiveness and polarization degree. These specific features are explained by the interaction of the defocusing action of distribution of the refractive index n(x) in the plane of the p-n-transition with a minimum under the center of the stripe contract (at x=0) with the focusing action of the gain coefficient distribution. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 461–464, July–August, 2000.