Absorption Related to Electrochromism in Cubic Boron Nitride Single Crystals

A unusual electrochromism is observed in amber cubic boron nitride （cBN） single crystals when breakdown possibly related to impurities and defects occurs. The electrochromism induces an abrupt increase in the absorption coefficient of the cBN crystals within the visible and infrared region. The change of the absorption coefficient of cBN crystal can be increased linearly by raising the current after the electrochromism occurs, whereas it is irrelevant to the polarization of the incident light. The absorption related to the electrochromism in the cBN single crystal has potential applications in designing and manufacturing electro-optical modulators, optical switches, and other optoelectric devices.     

雄激素非依赖前列腺癌细胞系代谢组学的初步研究

探讨雄激素依赖性前列腺癌LNCaP细胞系向雄激素非依赖性前列腺癌细胞系(LNCaP-AI和LNCaP-AI+F)转变过程的代谢组学变化,寻找前列腺癌发生雄激素耐药的可能发生机制.利用超高效液相色谱-四极杆-飞行时间质谱,在电喷雾电离源在正离子模式下,采用60%(V/V)甲醇-0.85%(w/V)NH4HCO3溶液在-4...     

Quadratic nonlinear response to 1.56-μm continuous wave laser in semi-insulating GaAs

The nonlinear photoresponse to a 1.56μm infrared continuous wave laser in semi-insulating （SI） galliu- marsenide （GaAs） is examined. The double-frequency absorption （DFA） is responsible for the nonlinear photoresponse based on the quadratic dependence of the photocurrent separately on the coupled optical power and bias voltage. The electric field-induced DFA remarkably affects the native DFA in SI GaAs. The surface electric field or the surface band-bending of SI GaAs significantly affects the magnitude variation of the Dhotocurrent and dark current     

Experimentally distinguishing electro-optic effects in silicon

Different electro-optic effects, such as Kerr effect, Pockels effect induced by the electric field or strain, and plasma dispersion effect exist in silicon. Experimentally distinguishing these effects is necessary for designing silicon-based electro-optic devices. According to their different polarization dependencies and frequency responses, these effects are measured and distinguished successfully via a transverse electro-optic modulation experiment based on the near-intrinsic silicon sample. The results indicate that Pockels effect induced by the electric field or strain is primary among these effects in the near-intrinsic silicon sample.     

Measurement of third-order nonlinear optical susceptibility of synthetic diamonds

Diamonds are wide-gap semiconductors possessing excellent physical and chemical properties;thus,they are regarded as very appropriate materials for optoelectronic devices.Based on the Kerr effect,we introduce a simple and feasible method for measuring the third-order nonlinear optical susceptibility of synthetic diamonds.In the experiments,synthetic type I diamond samples and transverse electro-optic modulation systems are utilized.As for the laser with the wavelength of 650 nm,the third-order susceptibility and Kerr coefficient of the diamond samples are obtained at χ(3)1212= 2.17 × 10-23 m2/V2 and S44 = 1.93 × 10-23 m2/V2,respectively.     

Physical mechanism of two-photon response in semi-insulating GaAs

The physical mechanism of two-photon response （TPR） in semi-insulating GaAs is studied. The measured photocurrent generated from the fabricated hemispherical GaAs sample responding to 1.3μm continuous wave laser shows a quadratic dependence on the coupled optical power and no saturation with the bias. The angular dependence of the photocurrent on the azimuth is in agreement with the anisotropy of double-frequency absorption （DFA） in GaAs single crystals. These results demonstrate DFA is the dominant mechanism of TPR in GaAs.     

亚微米外部电光检测技术

将固浸透镜技术与电光检测技术相结合，建立了具有亚微米空间分辨率的外部电光检测系统，通过使用GaAs半球作外部电光探头，用数值孔径为0.3的显微物镜对波长为1.3μm的探测光束进行聚焦，得到了半峰全宽直径为0.7μm的聚焦光斑，成功测量了微带线上10kHz的正弦波信号，验证了系统的线性响应特性，并得到了6mV/√Hz的电压灵敏度。     

Measurement of the linear electro-optic tensor of cubic boron nitride single crystals

The transverse electro-optic(EO)modulation system is built based on cubic boron nitride(cBN)single crystals unintentionally doped and synthesized at a high pressure and high temperature.The photoelectric output of the system includes two parts that can be measured respectively and the value of elements in the linear EO tensor of the cBN crystal can be obtained.This method does not need to measure the absolute light intensity.All of the surfaces of the tiny cBN crystals whose hardness is next to the hardest diamonds are{111}planes.The rectangular parallelepiped cBN samples are obtained by cleaving along{110}planes and subsequently grinding and polishing{112}planes of the tiny octahedral cBN flakes.Three identical non-zero elements of the EO tensor of the cBN crystal are measured via two sample configurations,and the measured results are very close,about 3.68 and 3.95 pm/V,respectively,which are larger than the linear EO coefficients of the general III-V compounds.     

硅材料的场致线性电光效应

从经典的极化理论出发,分析了直流电场、低频调制电场和光波电场共同存在时硅材料折射率的变化,从理论上揭示了场致线性电光效应的物理实质.以近本征硅材料为样品,采用金属-绝缘体-半导体样品结构,搭建了由塞纳蒙(Senarmont)补偿器改进成的横向电光调制系统.在硅材料空间电荷区内观测到显著的线性电光调制效应,系统的半波电压小于170 V,从实验上直接证实了硅材料中内建电场诱导的场致线性电光效应的存在.此外还观测到由克尔效应引起的二次电光凋制信号.以及由场致光整流效应引起的、随线偏振光的方位角的二倍余弦变化的电信号.实验结果与经典极化理论的预期完全一致,也间接证实了硅材料中场致线性电光效应的存在.     

硅光电二极管的双光子响应

报道用连续光1.3μmInGaAsP半导体激光器探测硅光电二极管中的双光子响应(我们把倍频效应和双光子吸收统称为双光子响应).通过实验,证明在硅光电二极管中必然有倍频吸收引起的光电流存在.