共查询到19条相似文献,搜索用时 109 毫秒
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光折变自适应光外差探测系统理论研究 总被引:4,自引:1,他引:3
首次对光折变自适当光外差探测系统的工作状态进行了较全面分析。给出了系统的最小可探测信号功率和可提供的参考光功率,指出了影响系统特性的关键参数。 相似文献
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光折变效应和带输运模型 总被引:1,自引:0,他引:1
由于光折变效应的光学非线性与光强无关,因而在低功率激光作用下也会产生显著的光学非线性效应.同时光折变效应具有非局域响应性,这导致光耦合的光能不可逆转移.这为通过非线性作用放大信号光提供了一种新途径.由于这些特性,自1966年发现光折变效应以来,它一直是非线光学领域内较为后跃和引人注目的研究课题,其应用也十分广泛.本文介绍了描述光折变效应的Kukhtarev带输运模型,并从Kakhtarev方程出发讨论了在稳态条件下的光折变性质,说明光折变效应的起因. 相似文献
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对光折变晶体事的光互联进行了研究,提出了一种利用桥式互泵浦位相共轭器在同一种光路下实现光开关,广播式,合成式及点点式光互联的方法,同时研究了利用光折变两波耦合进行了光互联的强度和时间特性。 相似文献
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The dynamics of semiconductor lasers with photorefractive phase conjugate optical feedback are experimentally studied. Photorefractive fringes considered here are rather static compared with time fluctuations of laser output power. Therefore, it is expected that a semiconductor laser with photorefractive feedback shows similar dynamics to those with conventional optical feedback. We examine relaxation oscillation and external cavity modes of laser output power in the presence of photorefractive phase conjugate feedback. It is proved that the dynamics of photorefractive phase conjugate feedback are fundamentally the same as those of conventional optical feedback. 相似文献
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提出一种利用CO2激光热固定的层状光折变体相位全息在一块晶体内实现一个固态微小化光学系统的方法理论分析证明利用双面线状激光加热的方案可以形成适合热固定的层状温度分布,初步实验中,在一块LiNbO3光折变晶体中建立了单级的修正的gamma网络,由此表明把一个复杂的光学系统微小化组装在单块的晶体中是可行的。 相似文献
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In this paper, we review recent progress of research on the photorefractive effect of ferroelectric liquid crystals. The photorefractive effect is a phenomenon that forms a dynamic hologram in a material. The interference of two laser beams in a photorefractive material establishes a refractive index grating. This phenomenon is applicable to a wide range of devices related to diffraction optics including 3D displays, optical amplification, optical tomography, novelty filters, and phase conjugate wave generators. Ferroelectric liquid crystals are considered as a candidate for practical photorefractive materials. A refractive index grating formation time of 8–10 ms and a large gain coefficient are easily obtained in photorefractive ferroelectric liquid crystals. 相似文献
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We report on the formation of spatial optical solitons in photorefractive media using picosecond laser pulses. Solitons are
generated with laser pulses in the visible and infrared wavelength region using photorefractive strontium barium niobate.
The dynamics of the soliton formation and the region of existence is studied in detail. 相似文献
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Narrowband tuning of a pulsed optical parametric oscillator (OPO) is achieved with a self-adaptive injection-seeded optical cavity employing a phase-conjugate reflector. This approach is used in a novel OPO system based on periodically poled KTiOPO4 and pumped at 532 nm by a pulsed Nd:YAG laser. The OPO is injection seeded at 835-855 nm by a continuous-wave tunable diode laser, which also enables a Rh:BaTiO3 photorefractive crystal to act as a wavelength-selective phase-conjugate reflector, with no need for active control of cavity length. The single-longitudinal-mode tunability and operational simplicity of this OPO system are demonstrated experimentally. 相似文献
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For a nonlinear medium, a given incident laser beam may produce different transmitted light waves. This phenomenon (the so-called optical bistability) corresponds to multiple solutions of the boundary value problems of the nonlinear Helmholtz equation. Optical bistability can be useful in the design of optical switches. Devices that display this behavior could potentially play a major role in the development of optical communication systems and computing. In this article we present experimental results concerning the optical bistability in photorefractive BaTiO3:Fe crystal. Two laser beams were used to interact with the photorefractive crystal which resulted in the bistability of the intensity of transmitted wave. This was achieved without the application of any optical resonator. High contrast optical bistability is found experimentally in the pump-ratio dependence of the output intensity. 相似文献
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A method of tomographic imaging is proposed in which two-wave mixing in a photorefractive crystal is used with wavelength scanning of a laser diode and phase modulation of the pump beam. This method provides full optical processing and is effective for weak light from objects because of the use of two-wave mixing. The depth resolution of the method was ~1 cm when the wavelength-scanning width was ~0.02 nm . 相似文献
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We demonstrate a photorefractive incoherent-to-coherent optical converter driven by ultraviolet light that provides a 35-mus response time and an optical resolution of 124 line pairs/mm. The device, implemented in KNbO(3) , operates with a modulating intensity of 85 mW/cm(2) , which corresponds to an optical switching energy per bit of 0.5 pJ. A conversion rate of the order of 90 Gbits/(s cm(2)) is achieved. The conversion between the ultraviolet light and the visible laser beam at lambda=532 nm occurs through anisotropic Bragg diffraction at a modulated interband photorefractive grating. Our device has a better optical resolution and conversion rate than optically addressed solid-state spatial light modulators based on the photorefractive effect and multiple quantum wells, and it is also faster than devices based on liquid crystals. 相似文献
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Encrypted optical memory system using three-dimensional keys in the Fresnel domain 总被引:11,自引:0,他引:11
An encrypted optical memory system using double random phase codes in the Fresnel domain is proposed. In this system, two random phase codes and their positions form three-dimensional keys for encryption of images and are used as keys to recover the original data. The third dimension is the positions of the codes, which can have as many as three degrees of freedom. Original images encrypted by use of the two phase codes located in the Fresnel domain are stored holographically in a photorefractive material. We demonstrate in preliminary experiments encryption and decryption of optical memory in a LiNbO(3) :Fe photorefractive crystal by use of angular multiplexing. 相似文献