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Presents a study which examined the use of the photorefractive effect in the design of optical limiters. Discussion of fanning limiters; Experiment; Details of oscillator limiters.

Deals with grafting competition for charge carriers in photorefractive bismuth silicon oxide. Effects of competition between multiple gratings for charge carriers on degenerate four-wave mixing; Analysis of the destructive interference between two phase conjugates; Examination of grating competition dynamics without pre-existing gratings in the medium.

In this paper, we report on gold nanoparticle (GNP) doped silk films as an implantable and degradable heating element activated by light, which can be potentially used for wireless powering of implanted microdevices. Proof-of-concept experiments have been conducted by casting a GNP doped silk film on a miniature thermal-power chip, which generates ∼20 mW when illuminated by a green laser with an output power of 450 mW/mm2 at 532 nm. [ABSTRACT FROM AUTHOR]

We investigate numerically and experimentally all-optical control of particles inside water filled, silica, hollow-core photonic crystal fiber (HC-PCF). We use an optical trapping beam focused outside the fiber, through its microstructure, perpendicular to the HC-PCF and independent of the guided fiber core mode. Finite difference time domain simulations model trapping through HC-PCF microstructure: trapping along the length of the HC-PCF is well maintained despite the significant effects due to scattering of the HC-PCF core structure. Trapped silica microspheres inside a HC-PCF is demonstrated experimentally as a reversible, reliable technique to control particles in fiber independent of the guided fiber mode. We observe a broadband attenuation of the HC-PCF transmission upon loading a silica microsphere into the fiber core. [ABSTRACT FROM AUTHOR]

This article presents a simple and novel method for the fabrication of cylindrical microchannels in polymer or biopolymer substrates. This process results in highly regular, cylindrical microchannels, suitable both to the transport of liquid and the transmission of light. This method eliminates issues associated with positioning tolerances characteristic of conventional fabrication techniques, such as soft lithography. Such devices hold great promise in the field of biomedical engineering by providing a true cylindrical profile for microflow studies and vascular modeling, as well as the ability to optically analyze injected biological samples. An evaluation of these devices is performed by real time optical imaging of blood flow. [ABSTRACT FROM AUTHOR]

Cantilevers are commonly used in microelectromechanical systems for sensing and optical switching applications. The authors demonstrate the use of optical tweezers for all optical actuation of a tapered optical fiber used as a cantilever and to drive it as a micromechanical oscillator. A fiber optic confocal detection system is used to monitor backscattered trapping light to sense the position and oscillation characteristics of the cantilever. Potential applications include optical switching and dynamic reconfigurability of photonic circuits. [ABSTRACT FROM AUTHOR]

We introduce a class of highly compact refractometers integrated onto a planar microfluidic geometry that demonstrates high resolution refractive index measurements in 50 μm fluid channels utilizing a Fabry–Perot cavity formed between resonant Bragg grating reflectors. This cavity forms a resonant peak in the transmission spectrum which is dependent upon the refractive index of the fluid in the microfluidic channel. We demonstrate this class of refractometer using optical fiber Bragg gratings; to provide high resolution, intracavity losses are minimized using integrated collimating optics. The refractometer can resolve refractive index changes of 0.2% and is simulated using coupled mode theory. [ABSTRACT FROM AUTHOR]

Studies the structural and quadratic electro-optic properties in lead magnesium niobate titanate thin films as a function of the fraction x of lead titanate. Morphotropic phase boundary compositions; Growth of the films on sapphire substrates; Total lead content in each composition using energy dispersion spectrum analysis.

We report experimental demonstrations of the use of a photorefractive barium titanate ring passive phase conjugate mirror in the coherent coupling of two GaAlAs diode lasers. By cooling the crystal towards its tetragonal to orthorhombic phase transition, we were also able to achieve infrared photorefractive phase conjugation with gain. [ABSTRACT FROM AUTHOR]

Because the ring and semilinear passive phase conjugate mirrors use dynamic transmission holograms, they are insensitive to vibration and may be pumped with light of short coherence length or with picosecond mode-locked laser light. Experimental demonstrations of these modes of operation are described. [ABSTRACT FROM AUTHOR]

We report photorefractive passive phase conjugation of GaAlAs laser radiation at 815–865 nm and Ar+ laser radiation at 1090 nm. A ring passive phase conjugate mirror was used with BaTiO3 as the real-time holographic gain medium. With GaAlAs lasers phase conjugate reflectivities of up to 16% uncorrected for Fresnel losses were recorded. Effects of the strong associated feedback to the laser and attempts at mode locking are described. At 1090 nm the reflectivity remains approximately the same, but with a significantly longer time constant. [ABSTRACT FROM AUTHOR]

A self-pumped phase conjugating mirror in conjunction with a traveling-wave acousto-optic modulator can be used to derive a spatially undisplaced frequency translatable optical beam. One can also obtain a beam consisting of multiple optical frequencies spaced by twice the modulator drive frequency. We find that the appropriate measure of the phase conjugating mirror's ability to retroreflect a moving optical beam can be its response (writing) time, its memory time, or the ratio of the two, depending on how the beam is moving. [ABSTRACT FROM AUTHOR]

Bistability and hysteresis have been observed in a photorefractive passive phase conjugate mirror. A threshold basis for the effect is presented and the results of an experimental demonstration of the device are given. [ABSTRACT FROM AUTHOR]

Passive phase conjugation of up to six lines (457, 476, 488, 496, 501, and 514 nm) of the all lines output of an argon ion laser is reported. Imaging characteristics and reflectivity measurements are given. In general, multiline operation results in some loss in both reflectivity and image resolution. This work opens the possibility for passive phase conjugation of full color images. [ABSTRACT FROM AUTHOR]

The photorefractive effect is demonstrated for the first time in ferroelectric lead germanate crystal (Pb5Ge3O11). An intensity coupling constant of Γ=2.3 cm-1 was measured at wavelength λ=514.5 nm in two-beam coupling experiments. [ABSTRACT FROM AUTHOR]

A dynamically reprogrammable optical interconnect is demonstrated using temporally multiplexed writing beams in photorefractive double phase conjugation to achieve arbitrary fan-out and fan-in. Applications to neural networks and image transmission through thick distortions are discussed. [ABSTRACT FROM AUTHOR]

Highly (110)-oriented and (100) nearly epitaxial 0.7PMN-0.3PT thin films were deposited on (1012) sapphire and (100) LaAlO[sub 3] substrates, respectively, using a dip-coating method. Optical waveguide characterization and electro-optic effect measurements of the film on sapphire substrate were demonstrated. Low propagation loss of 4.1 dB/cm and high quadratic electro-optic coefficient of 0.75×10[sup -16] (m/V)[sup 2] were obtained at wavelength of 632.8 nm. Epitaxial PMN-PT thin films will be suitable for integrated optic devices. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We measure the spectral characteristics of an external cavity semiconductor laser which uses a phase conjugate mirror for its external reflection. This device has significant advantages over the conventional external cavity system owing to the self-aligning nature of the phase conjugate mirror. The fiber delay line self-heterodyne technique is used to measure the fundamental linewidth for single mode operation of this device. It shows the linewidth to be at least as narrow as the instrumental resolution of 100 kHz. [ABSTRACT FROM AUTHOR]

Frequency detuning effects in photorefractive oscillators are used in a new type of (passive) interferometry which converts optical path length changes to frequency shifts. Such an interferometer is potentially more accurate than conventional interferometers which convert optical path length changes to phase or intensity changes. [ABSTRACT FROM AUTHOR]

We report here for the first time the demonstration of self-pumped phase conjugation in photorefractive semiconductors using 1.32 μm light. Using an ac field technique to enhance the gain coefficient in InP:Fe and a single input pump beam, phase conjugate reflectivities of 11% were measured using an input beam intensity of less than 1 mW/mm2. These results open up many possibilities for using photorefractive semiconductors in applications with low-power infrared diode lasers. [ABSTRACT FROM AUTHOR]