Pierre J. Talbot

Self-defocusing, self-focusing, and speckle in LiNbO 3 and LiNbO 3 :Fe crystals

The characteristics of light-induced scattering in LiNbO(3) and LiNbO(3):Fe crystals are studied. The experimental and theoretical results show that the light-induced scattering for an extraordinary illumination beam consists of self-defocusing, self-focusing, and speckle. They are caused by the light-induced lensing and fluctuation of the refractive index in the crystals.

Polarization sensitivity of birefringent photorefractive holograms and its applications to binary switching

The effect of polarization sensitivity on the intensity and the resolution of the diffracted beams from a birefringent photorefractive hologram is investigated. In addition, an optical switching technique based on the sensitivity is demonstrated. The method is capable of implementing a large number of 2 x 2 switching channels with only four holograms. The on/off ratio of the switches can easily reach 100:1. This switching methodology is applicable to either synchronous or asynchronous interconnection with a variety of photorefractive materials.

PLZT Based High-efficiency Electro-optic Grating for Optical Switching

Abstract A high diffraction efficiency electro-optic phase grating is fabricated by depositing transparent interdigital electrodes on a lanthanum-modified lead zirconate titanate ceramic wafer. The diffraction efficiency is controlled by an applied d.c. voltage. The zero-order light is completely shut off when the first-order diffraction reaches its maximum, with a voltage of 140 V. The device can be used as a voltage-controlled switch in optical interconnects.

Optical switching with photorefractive polarization holograms

A switching technique that uses the polarization sensitivity of photorefractive holograms in crystals is experimentally demonstrated. The design is capable of handling a large number of 2 x 2 switching channels with only four holograms. The concept is applicable to either synchronous or asynchronous switching and also to a variety of photorefractive materials.

Anisotropic light-induced scattering and position dispersion in KNbO3:Fe crystal

Abstract The characteristics of polarization-anisotropic scattering and “position dispersion” of KNbO 3 :Fe crystal are investigated. Different from the previously reported scattering mechanism in LiNbO 3 and LiTaO 3 , in which the scattering arises from the amplification of weak beams scattered by bulk and surface inhomogeneities, the scattering from KNbO 3 :Fe is shown to be mainly due to the light-induced lensing.

MATRIX-VECTOR MULTIPLICATION BY USING PINHOLE HOLOGRAMS

Optical matrix-vector multiplication by using pinhole holograms fixed in a photorefractive crystal is experimentally demonstrated. This method offers the advantages of large holographic storage capacity and high-speed programmability. It can be useful in some expert systems that require only a finite number of large matrices to be updated quickly for high-speed matrix-vector multiplication.

Design and simulation of PLZT-based scanning grating lobe optical array generators

Abstract The unique properties of quadratic lead lanthanum zirconate titanate (PLZT) compositions make feasible the development of scanning grating lobe optical array generators. Scanning optical array generators would facilitate the alignment of optical interconnect architectures and could provide a critical technology for the implementation of parallel addressing schemes in threedimensional optical memories. A three-port implementation of a PLZT-based scanning optical array generator is presented. The three-port implementation offers a significant reduction in the maximum electrode voltage required to effect a specific scan angle.

PLZT/ITO grating for optical switching and reconfigurable optical interconnect applications

A 2D optoelectronic diffraction grating based on PLZT ceramic material for optical switching and reconfigurable optical interconnect applications is demonstrated. Integrable chips are fabricated consisting of numerous fine interleaved transparent indium-tin oxide electrodes on a polycrystalline PLZT ceramic substrate. The chips measure one centimeter square. Electrode features are scales and measure from 12.5 micrometers to 100 micrometers . Reported here are chip material and fabrication details.

Design and analysis of an optical interface processor for signal processing applications

A preliminary design is presented for an Optical Interface Message Processor (OPTIMP) which exploits the high bandwidth, parallelism, multidimensional capability, and high storage density offered by optics. In the proposed system, the time-consuming operations in parallel processing networks, such as switching and routing, are fully implemented in optics. The design is free from optical/electrical conversion bottlenecks and can perform switching and routing in the Gigabits/s range. The design can be adapted for interconnection networks for massively parallel computers.

Holographic optical switching with photorefractive crystals

A switching technique using the polarization sensitivity of photorefractive holograms in crystals is experimentally demonstrated. The design is capable of handling a large number of 2 X 2 switching channels with only four holograms. The concept is applicable to either synchronous or asynchronous switching and also to a variety of photorefractive materials.