A zinc oxide (ZnO) single crystal microtube fabricated by using an encapsulated microwave-heating growth
method has been reported. This microtube has a highly symmetrical hexagonal tubular structure, and exhibits
strong near-band-edge emission, highly selective UV light response, and excellent electron field emission. In this
paper, we study the converse piezoelectric properties of the microtube by using a sensitive modified Michelson
laser interferometer. The experimental results demonstrate that this hexagonal hollow structure has very
interesting piezoelectric properties compared with bulk ZnO crystals.
In this paper, a new speckle based hologram multiplexing recording technique is proposed and tested. In
this method, a multi-mode LiNbO3 single crystal fiber is employed to generate speckle patterns which are
used as reference beams in hologram recording process. The speckle pattern generation can be precisely
controlled by external E-field. Theoretically, this technique can generate thousands of decorrelated
reference beams at given practical constraints. Its storage capacity can be scaled up as material properties
are improved, making it well adapted to new material development. A theoretical analysis and numerical
simulation of speckle pattern generation are also presented in this paper.
A new method of phase-coded multiplexing is proposed and tested. The construction of this multiplexing scheme combines a rotating cylindrical-collimating lens system (RCCLS) with a random phase transparent mask. It is verified that such a system is capable
of storing over 1000 images in a doped LiNbO3 crystal. Experimental results and theoretical analyses presented in this paper demonstrate that a compact, all optical, secure and high capacity volume holographic memory system can be implemented with further exploitation
of the method.
In electro-optic (EO) modulator devices ferroelectric crystals of strontium barium niobate (SBN) are attractive due to exceptional high EO coefficients and low half wave voltage. SBN single crystals grown by laser heated pedestal growth are investigated to explore frequency dependent EO property at low frequency and near resonant frequency range. The mechanism of its frequency dependence is discussed briefly.
In this research Electronic Fiber Speckle Pattern Interferometry (EFSPI) is proposed to investigate the area of directional sensing. Modal phasing caused speckle field phase variation was discussed and the sensor architecture based on electronic fiber speckle pattern interferometry (EFSPI) is proposed. The concept of vector sensing with EFSPI was analyzed and experimentally verified with fiber speckle interferogram results, signaling a great potential for directional sensing.
Optical spectrographic processing systems have been shown to be the most widely used techniques for time-varying signals that usually contain very distinct characteristics in spectral distributions and are difficult to categorize in time (spatial) domain. In this paper, an optical architecture for spectrograph generation, by which time-varying signal processing can be performed, is proposed and its implementation is described in detail. Some potential applications using optical spectrographic processing system in phonetics, linguistics, speech identification are investigated. Simulation results are also presented to demonstrate the effectiveness of the optical spectrographic processing system in those application areas. Other applications of the optical spectrographic analysis system in identifying individuals through "voice prints" or in detecting mechanical fatigue through abnormal noise are also indicated.
Thermal electron dynamics at the interfaces of thin gold film/ferroelectric lithium niobate (LiNbO3) is studied by using step-function type laser irradiation. Our measurements reveal an anomalous transient optical transmission fluctuation caused by thermal electron dynamics at the interfaces. To our knowledge, such phenomenon and its theoretical explanation haven't been reported.
In this paper we report the design and implementation of a multimode fiber sensing technique for displacement sensing. To exploit the spatial information contents for sensing, a multimode fiber specklegram sensor with a hetero-core fiber structure is used. The sensor utilizes the inner product of multimode fiber speckle fields, which is highly sensitive on the geometrical shape change of the sensing section. The sensitivity and the dynamic range of the displacement sensing are investigated for hetero-core structure fiber specklegram sensor and straight multimode fiber specklegram sensor. It’s found that the sensitivity of the hetero-core FSS offers sensitivity as high as 0.1 μm, with a dynamic range of about 3 μm, which is superior to straight structure multimode fiber FSS. Dynamic response of the hetero-core FSS for displacement sensing was also studied.
Optical windows have been widely used in optical spectrographic processing system. In this paper, various window profiles, such as rectangular, triangular, Hamming, Hanning, and Blackman etc., have been investigated in detail, regarding their effect on the generated spectrograms, such as joint time-frequency resolution ΔtΔw, the sidelobe amplitude attenuation etc.. All of these windows can be synthesized in a photorefractive crystal by angular multiplexing holographic technique, which renders the system more adaptive. Experimental results are provided.
KEYWORDS: Multiplexing, Holograms, Wavefronts, Crystals, Volume holography, Beam splitters, 3D image reconstruction, Holography, Laser crystals, Signal to noise ratio
We propose a phase-coded multiplexing method that employs the rotation of a crossed cylindrical-collimating lens system to encode the reference beam of each multiplexed hologram for volume hologram storage. This phase coding scheme is compared with that based on random phase-coded multiplexing. Our experimental results demonstrate that the method can simplify the procedures of recording and reading in hologram storage.
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