C. M. Verber

Correlator based on an integrated optical spatial light modulator

The fabrication and characterization of a 17.5-M bit/sec integrated optical correlator are described. The correlator makes use of a novel programmable electrooptic spatial light modulator in conjunction with a digitally modulated surface acoustic wave.

Focal properties of geodesic waveguide lenses

The focal properties of uncorrected geodesic lenses in ion‐exchanged glass waveguides are reported. A 13.8‐mm‐focal‐length lens resolved by beams with an angular separation of 27.6 mrad, while a 28‐mm‐focal‐length lens resolved beams with an angular separation of only 3.3 mrad. Intensity profiles of the focal region of the former lens revealed a 40‐μ spot size when the input aperture was 5 mm, and a spot size of 7.7 μ when the aperture was reduced to 1 mm. This value is close to the diffraction‐limited spot size of 5.7 μ.

27Al and 89Y nuclear magnetic resonance in yttrium-aluminum garnet

Abstract From the 27 Al resonances, the values of e 2 qQ / h were determined to be 0.632 ± 0.005 Mc/s and 6.017 ± 0.017 Mc/s in the trigonal and tetragonal sites respectively. Neither the 27 Al nor the 89 Y resonances are shifted significantly.

Two‐step excitation of fluorescence in iodine monochloride vapor

Two‐step sequential excitation of fluorescence was produced in ICl vapor using two synchronized tunable laser sources. The pumping scheme involved the E←A←X electronic transitions with subsequent E→A transitions being observed in fluorescence.

Holographic formation of gratings in optical waveguiding layers

Thick phase gratings were formed photorefractively (through optically induced refractive index changes) in planar optical waveguides by intersecting short−wavelength coherent guided beams. In multimode guides formed by effusing Li from LiNbO3, maximum diffraction efficiencies were 52% at the 0.488−μm write wavelength and 3.1% at 0.633 μm. In a two−mode LiTa1−xNbxO3 guide formed by diffusing Nb into LiTaO3 at 1100 °C, diffraction efficiencies were 65% and 28% at the same two wavelengths, respectively.

Large-angle optical switching in waveguides in LiNbO3

Abstract Optical waveguiding layers displaying great photorefractive sensitivity have been formed by diffusion of iron into LiNbO3. Thick phase gratings of greater than 50% diffraction efficiency have been formed within such waveguiding layers by intersecting guided beams of red light from a He-Ne laser. By writing the gratings in a sample heated to 160°C, fixed gratings of about 1% diffraction efficiency have been produced. Modulation of the diffracted beam by electro-optic deflection of the input beam has been demonstrated.

Stoichiometry dependence of lithium outdiffusion in LiNbO3

Measurements by Mach‐Zehnder interferometry of the refractive‐index changes near the surface of outdiffused LiNbO3 crystals indicate that, in agreement with recent results of Noda et al. [J. Appl. Phys. 51, 1379 (1980)], the rate of lithium outdiffusion is greater for more nearly stoichiometric crystals. The activation energy for diffusion of Li does not vary significantly with stoichiometry. The Li diffusion coefficient is also higher in the relatively Li‐depleted regions near the surface.

Hybrid incoherent optical pattern recognition system

A pattern recognition system that uses incoherent spatial filtering to recognize images directly from a narrowband phosphor television monitor is described. Images of real objects are captured with a television camera. These images are then edge-enhanced electronically and displayed on the TV monitor. The monitor output is used directly as the input to a holographic correlator. An optical multichannel analyzer at the correlation plane is used to analyze the shape of the correlation function and to determine the position of its peak. Experimental results agree well with theory. Concepts for handling rotation, aspect angle, and scale variations of the input are discussed.

Design and performance of an integrated optical digital correlator

We describe an integrated optical correlator capable of performing ordinary binary or bipolar correlations. The device consists of two surface-acoustic-wave (SAW) transducers and an electrooptic spatial light modulator in a planar Ti in-diffused LiNbO 3 waveguide. It is designed to correlate a 32-bit word at a 32-Mbit/s data rate.

Formation of integrated optics components by multiphoton photorefractive processes

Phase holograms have been formed in pure outdiffused LiNbO3 waveguides using the photorefractive effect initiated by two‐photon absorption. Efficient holograms were recorded with two guided waves, of less than 100 W peak power, and less than 10 μJ optical energy. This technique automatically compensates for wave front perturbations in the guide and allows the formation of various integrated components such as wavelength multiplexers and optical switches.