Resonantly pumped Q-switched Er:GdVO4 laser

We describe a Q-switched Er:GdVO₄ laser resonantly pumped by a MgO-doped periodically poled LiNbO₃ optical parametric oscillator （MgO: PPLN OPO） at 1536 nm. In continuous-wave lasing, the maximum output power is 1.14 W with an incident pump power of 4.7 W and a slope efficiency of 27%. In Q-switched operation, 1.1 mJ of output pulse energy is achieved at 200 Hz. The upper-state lifetime at different pulse repetition frequencies is also calculated.     

General coordinate invariance and conformal invariance in nonrelativistic physics: Unitary Fermi gas

We show that the Lagrangian for interacting nonrelativistic particles can be coupled to an external gauge field and metric tensor in a way that exhibits a nonrelativistic version of general coordinate invariance. We explore the consequences of this invariance on the example of the degenerate Fermi gas at infinite scattering length, where conformal invariance also plays an important role. We find the most general effective Lagrangian consistent with both general coordinate and conformal invariance to leading and next-to-leading orders in the momentum expansion. At the leading order the Lagrangian contains one phenomenological constant and reproduces the results of the Thomas-Fermi theory and superfluid hydrodynamics. At the next-to-leading order there are two additional constants. We express various physical quantities through these constants.     

Polarization-dependent carrier dynamics in a passive InAs/InP quantum dot waveguide

We investigate carrier dynamics in a passive InAs/InP quantum dot (QD) waveguide using 255 fs optical pulses at a central wavelength of 1568 nm. We observe strong anisotropy of absorption saturation for different polarizations. Pump-probe measurements indicate the presence of carrier relaxation dynamics on a timescale in the order of tens of picoseconds due to cascaded relaxation of carriers generated by two-photon absorption (TPA) from the bulk region to the QDs via the wetting layer. These relaxation timescales are much longer than in QD amplifiers. Our observations are supported by a rate-equation model which includes TPA, showing good agreement with the pump-probe measurements.     

Generic Bell inequalities for multipartite arbitrary dimensional systems

We present generic Bell inequalities for multipartite arbitrary dimensional systems. The inequalities that any local realistic theory must obey are violated by quantum mechanics for even dimensional systems. A large set of variants are shown to naturally emerge from the generic Bell inequalities. We discuss particular variants of Bell inequalities that are violated for all the systems including odd dimensional systems.     

非线性光学及其若干新进展

扼要介绍了非线性光学的基本概念及其最近10年来在飞秒激光，半导体材料，光纤通信和光信息存储等若干方面的研究进展。     

动态场空间分布实时测量装置的研究

描述了一套多路动态场空间分布实时测量系统，该系统是一套以微要为中心的数字化系统，可实现多路动态场空间分面睥精神病时测量。系统由微机、TMS320C50板、开关电路、检波器、传感器、放大器等设备构成硬件系统，并通过编制C50板嵌入式软件和微机主控程序实现系统功能。     

空间光学遥感器主镜加工过程中疲劳寿命研究

针对空间光学遥感器主镜镜面加工过程中,磨盘与主镜间磨削动作往复运行引起的主镜柔性支撑结构疲劳寿命问题,通过建立主镜组件的有限元模型,利用MSC.Fatigue软件按应力-寿命(S-N)法对主镜组件进行了疲劳寿命分析,确定了支撑结构的薄弱部位,并对仿真过程进行了误差分析,讨论了影响仿真结果的各个因素.对比热真空试验和动力学试验前后主镜镜面面型数据,验证了支撑结构加工、设计参量的合理性.通过疲劳寿命仿真分析,可以有效预示光学结构在加工过程中的疲劳情况,为空间光学遥感器结构的设计、加工提供理论依据和参考.     

Continuous-wave and Q-switched Operation of a Tm,Ho:YAP ring laser

We demonstrated continuous-wave (CW) and Q-switched operation of a Tm,Ho:YAP ring laser at 77 K. The maximum CW output power of 2 W at 2130.7 nm was obtained under the incident pump power of 12 W, corresponding to a slope efficiency of 23% and an optical-to-optical efficiency of 16.7%. For the Q-switched regime the maximum output energy of 5 mJ with the pulse width of 160 ns at the repetition rate of 100 Hz was achieved, corresponding to a peak power of 31.25 kW.     

Photoluminescence properties of color-tunable SrMgAl10O17:Eu2+,Mn2+ phosphors for UV LEDs

Aluminate phosphors SrMgAl₁₀O₁₇ codoped with Eu²⁺ and Mn²⁺ ions were prepared by solid-state reaction. The phase structure and photoluminescence properties of the as-prepared phosphors were characterized by powder X-ray diffraction, photoluminescence excitation and emission spectra. Upon excitation of UV light, two broad emission bands centered at 470 and 515 nm were observed, and they were assigned to Eu²⁺ and Mn²⁺ emissions, respectively. The emission color of the phosphors can be tuned from blue to cyan and finally to green by adjusting the concentration ratios of Eu²⁺ and Mn²⁺. Effective energy transfer occurs from Eu²⁺ to Mn²⁺ in the host due to the spectral overlap between the emission band of Eu²⁺ and the excitation bands of Mn²⁺. The energy transfer mechanism was demonstrated to be electric dipole–quadrupole interaction. The energy transfer efficiency and critical distance were also calculated. The phosphors exhibit strong absorption in near UV spectral region and therefore they are potentially useful as UV-convertible phosphors for white LEDs.