参考光旋转—步法大视角彩虹全息术

本文分析了全息图视角受限制的主要原因，其原因是再现衍射光方向受到限制。针对这个原因，作者提出了同步旋转参考光、物体和干板，采用分时记录物体的信息，使全息图再现时形成多方向的衍射光波，从而达到扩大视角之目的。文章中给出了理论分析和实验装置及结果。     

半导体垂直腔面发射激光器的微腔效应

应用腔量子电动力学和半导体物理学讨论了半导体垂直腔面发射激光器的微腔效应,得到了实际腔结构和注入载流子下的半导体生趣腔面发射激光器的自发发射谱,计算结果表明,半导体分布布拉格反射垂直腔激光器的单方向自发发射可以境强约２００倍。     

纳米氧化锌的紫外自发辐射与受激辐射

纳米结构的氧化锌兼备了宽直接带隙(E_g=3.34eV)、强激子束缚能(60meV)的优良特性,同时又具备了纳米材料独特的微结构与光电功能,可望成为高效率紫外发光二极管以及低阈值紫外半导体激光器的良好材料。以我们的工作为基础,利用不同结构的ZnO作增益介质,概述了低维ZnO纳米材料中的自发辐射与受激辐射过程,观察到了放大的自发辐射(ASE)与受激振荡现象,并讨论了自发辐射、ASE及受激辐射的产生机制。     

Spectrum control and shaping of optical pulses in optical fibre interferometers

This paper discusses the use of single-mode fibre ring interferometers for injection laser line narrowing and for enhancement of optical emission power. The efficient launching into fibre ring interferometers of multi-frequency external cavity injection laser emission, in both the c.w. and mode-locking regime, has been achieved. Matching the optical lengths of the external cavity and fibre interferometer allowed the measurement of mode width of such a laser. A method is proposed for shaping optical pulses in fibre ring interferometers from constant intensity frequency modulated emission. The mode-locking regime of all-fibre external cavity injection lasers has been achieved.     

Scheme for Concentration of the <Emphasis Type="Italic">W</Emphasis> Class State via Cavity Decay

We propose a concentration scheme of the W class state via cavity QED technique. In our scheme the influences of cavity decay and atomic spontaneous emission have been considered. Furthermore, the atomic spontaneous emission has been suppressed by using non-radiative transitions in atoms with three-level structure, and the photonic qubit is used as flying qubit and atomic qubit as stationary qubit. Therefore our scheme is comparatively easy to realize within techniques presently available.     

Optical gain by simultaneous photon and phonon confinement in indirect bandgap semiconductor acousto-optical cavities

Optical gain that could ultimately lead to light emission from silicon is a goal that has been pursued for a long time by the scientific community. The reason is that a silicon laser would allow for the development of low-cost, high-volume monolithic photonic integrated circuits created using conventional CMOS technologies. However, the silicon indirect bandgap—requiring the participation of a proper phonon in the process of light emission—is a roadblock that has not been overcome so far. A high-Q optical cavity allowing a very high density of states at the desired frequencies has been proposed as a possible way to get optical gain. However, recent theoretical studies have shown that the free-carrier absorption is much higher than the optical gain at ambient temperature in an indirect bandgap semiconductor, even if a high-Q optical cavity is formed. In this work, we consider a particular case in which the semiconductor material is engineered to form an acousto-optical cavity where the photon and phonon modes involved in the emission process are simultaneously confined. The acousto-optical cavity confinement effect on the light emission properties is characterized by a compound Purcell factor which includes both the optical as well as the acoustic Purcell factor (APF). A theoretical expression for the APF is also introduced. Our theoretical results suggest that creating an acousto-optical cavity the optical gain can overcome the photon loss due to free carriers as a consequence of the localization of phonons even at room temperature, paving the way towards the pursued silicon laser.     

StimulatedC'-emission of Ag−-centers in KI,RbBr, and CsBr

Stimulated emission around 335 nm in theC' emission band of Ag^– centers in KI, RbBr, and CsBr has been observed at low temperatures and the gain coefficient in the band maximum has been determined. Laser action has been demonstrated using a simple broad band cavity.     

Investigation of the Purcell effect in photonic crystal cavities with a 3D Finite Element Maxwell Solver

Photonic crystal cavities facilitate novel applications demanding the efficient emission of incoherent light. This unique property arises when combining a relatively high quality factor of the cavity modes with a tight spatial constriction of the modes. While spontaneous emission is desired in these applications the stimulated emission must be kept low. A measure for the spontaneous emission enhancement is the local density of optical states (LDOS). Due to the complicated three dimensional geometry of photonic crystal cavities the LDOS quantity has to be computed numerically. In this work, we present the computation of the LDOS by means of a 3D Finite Element (FE) Maxwell Solver. The solver applies a sophisticated symmetry handling to reduce the problem size and provides perfectly matched layers to simulate open boundaries. Different photonic crystal cavity designs have been investigated for their spontaneous emission enhancement by means of this FE solver. The simulation results have been compared to photoluminescence characterizations of fabricated cavities. The excellent agreement of simulations and characterizations results confirms the performance and the accuracy of the 3D FE Maxwell Solver.     

Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA

Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient.     

Observation of Mode Patterns for High Purity Mode Operation in the Submillimeter Wave Gyrotron FU VA

Operation tests of a cavity designed for high purity mode operation of the submillimeter wave gyrotron FU VA has been carried out successfully. The observed emission patterns of several cavity modes appear very pure and are compared with calculated results. High purity mode operation has the advantage of making the conversion to Gaussian-like beams more efficient.     

Statistics of discrete photodetection of resonance fluorescence in the Mollow sidebands

A method is proposed for generating conditional single-photon states with a high degree of purity in a single-mode cavity by successive discrete photodetection. The cavity is pumped by resonance fluorescence emission from a source atom driven by a classical field. The cavity is tuned to a Mollow sideband. A relation between detector parameters is found that makes it possible to interpret the detection of a probe atom in the excited state as unambiguous evidence that a pure single-photon state has been prepared in the cavity. An expression is derived for the prior probability of such an event, and dependence of the one-photon state population of the cavity field on detuning, relaxation rate, and time is examined.     

Spontaneous emission in cavities: How much more classical can you get?

Cavity-induced changes in atomic spontaneous emission rates are often interpreted in terms of quantum electrodynamical zero-point field fluctuations. A completely classical method of computing this effect in terms of the unquantized normal mode structure of the cavity is presented here. Upon applying the result to a classical dipole radiating between parallel mirrors, we obtain the same cavity correction as that for atomic spontaneous emission in such a cavity. The theory is then compared with a recent experiment in the radio-frequency domain.It is a pleasure and an honor to dedicate this paper to Professor Asim O. Barut, who, as my teacher, advisor, and friend, has been a great inspiration to me as well as many, many others.Work supported by the National Research Council of the United States.     

Photo-pumped lasing from low density self-assembled InGaAs/GaAs quantum dots within a high-Q vertical cavity

A high-Q cavity containing three layers of self-assembled InGaAs/GaAs quantum dots has been prepared. Emission occurs in the wavelength range 1275–1285 nm over the wafer surface. We have observed lasing thresholds in the power-in-versus-power-out characteristics, with associated changes in the angular emission profile, when the structure is optically pumped CW at 300 K. At high pump powers spectrally resolved lateral modes are seen in the emission spectra of a planar cavity and this is discussed in terms of the index change induced by the pump laser.     

周视彩虹全息术

本文一改以往平板彩虹全息图垂直于全息图面观察的形式,给出一种几乎平行于全息图面观察的周视彩虹全息图的制作技术,这种全息图观察范围为360°最后给出了实验结果,并作了讨论.     

Steady-State Orbitron Emissions

The Orbitron maser has been operated at a pressure of 2 × 10-6 in the steady state. Electrons are supplied to the device by an oxide-coated tungsten cathode placed inside the cylindrical cavity. The plasma-free emission corresponded to harmonically related steady-state narrow lines. The fundamental (lowest frequency) line corresponds to a resonance in the cavity system, which could be observed with a grid-dip meter.     

‘神光Ⅱ’上冲击波法测量黑腔辐射温度

 在“神光Ⅱ”三倍频装置上,由黑腔产生的辐射驱动铝台阶样品产生冲击波,采用光学条纹相机测量冲击波速度,利用冲击波速度与黑腔辐射温度的定标关系,获得了与软X光能谱仪测量相一致的辐射温度;采用热波关系和能量守恒原理对辐射温度进行了分析,计算结果与实验结果一致。     

Concentration of Unknown Atomic Entangled States via Entanglement Swapping through Raman Interaction

We show that entanglement concentration of unknown atomic entangled states is achieved via the implementation of entanglement swapping based on Raman interaction in cavity QED. A maximally entangled state is obtained from a pair of partially entangled states probabilistically. Due to Raman interaction of two atoms with a cavity mode and an external driving field, the influence of atomic spontaneous emission has been eliminated. Because of the virtual excitation of the cavity mode, the decoherence of cavity decay and thermal field is neglected.     

Inhibition and enhancement of the spontaneous emission of quantum dots in structured microresonators

Spontaneous emission of quantum dot systems in laterally structured microcavities that exhibit photon confinement in all three directions has been studied by time-resolved photoluminescence spectroscopy. For on-resonance conditions, we find that the dot emission rate is increased substantially over that of the unstructured planar cavity. For off-resonance conditions, we are able to suppress the emission rate by an order of magnitude by using cavities with metal coatings, which we attribute to the suppression of leaky optical modes in these structures.     

A Decoherence-Reduction Scheme by Waveguides in Quantum Information Processing

Based on the result of cavity quantum electrodynamics, we suggest a method, in which the Fabry-Perot cavity or the confocal cavity is replaced by a waveguide with the size comparable to the wavelength of the photon, to reduce decoherence caused by spontaneous emission in quantum information processing, especially in the realization of quantum computation. Since a waveguide has a lowest cutoff frequency while a Fabry-Perot cavity or a confocal cavity has none, the spontaneous emission of excited atoms will be forbidden in an ideal waveguide with an appropriate size. To avoid the influence of the non-ideal conducting walls on the atom in a realistic waveguide, which will lead to decoherence, we suggest that the waveguide should be coated by a thin film of transparent insulating medium. In our method, the quantum information is represented by a multi-level atom or molecule; any two of its levels can be used to represent a qubit in principle. Our method greatly extends the choice of the material to be used in the realization of quantum computation, and it can be used in most schemes to reduce the decoherence caused by spontaneous emission.     

Two-dimensional liquid crystal laser array

A two-dimensional liquid crystal (LC) laser array has been demonstrated by photopumping a single LC sample using a lenslet array consisting of plano-convex microlenses. A 5 x 5 array of LC lasers (displaying evidence of mutual coherence) spaced by 1 mm inactive regions has been generated, which could be combined to yield a single monomode output and allows an almost 50-fold increase in energy density in comparison to a single-focus LC cavity. Furthermore, we have demonstrated how the individual and recombined emission spectra vary with different sample topologies and how polydomain samples can be used to generate a multiwavelength laser emission.