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Performance-limiting asymmetric distortion is observed in the spectra of fundamental pulses transmitted through GaAs-Al(0.9)Ga(0.1)As multilayer waveguides designed for surface-emitted second-harmonic generation. This behavior is attributed to refractive-index changes resulting from the accumulation of free carriers created by two-photon absorption in the GaAs layers. Numerical simulations of the intensity-dependent spectra by use of the separately measured two-photon absorption coefficient are shown to be in good agreement with the observed spectra.

Normal-incidence planar-optical waveguide-imbedded phase gratings of finite aperture width and length are analyzed with Svidzinskii's (Sov. J. Quantum Electron. 10, 1103 (1980)] two-dimensional Braggdiffraction theory. Svidzinskii's characteristic-grating equations are adapted for the rectangulargrating case, and an overlap integral is used to extend the theory to account for the mode structure of the waveguide. The combined theory is used to optimize the throughput of a system composed of an input grating coupler, a waveguide, and an output grating coupler for both the highly multimode (thickwaveguide) and the few-mode (thin-waveguide) cases.

The traditional design procedure for the waveguide Fresnel lens was carried over from those of bulk optics and micro-optics. In this design it is assumed that the lens thickness is negligibly small with respect to the focal length. This criterion does not hold for many integrated optic devices, in particular those with small mode-index modulations and long wavelengths. Under these conditions, the focal properties of the lens become unpredictable and the lens efficiency is reduced, both of which severely limit the usefulness of the lens as a waveguide-to-fiber coupler. To correct for this shortcoming, the standard Fresnel lens design procedure was modified to acocunt for the thickness of the lens explicitly. Both the standard and the modified Fresnel lens designs are outlined. A comparison of the limitations of the two lenses predicts better performance for the modified Fresnel lens. This is supported through computersimulation results for a pair of test lenses.

A model for analyzing the effects of material shrinkage on volume holograms is presented. This model is based on the fringe-plane rotation model used for describing the effects of plane-wave grating holograms that undergo shrinkage. A computer was used to exercise the model for a simple input object typical of those used in digital holographic memory applications and stored as a Fourier-transform hologram. The theoretical formulation of the model is presented as well as the results of the numerical analysis.

Two computer models are presented that can be used to determine the image formed by a 4-∱ Fourier imaging system with an aperture in the Fourier-transform plane of the system. These models were designed to aid in the selection of system parameters in a Fourier-transform hologram recording system (namely, object size, feature ratio, focal length, and storage area) required to obtain a retransformed image of a given quality. The results of the simulations are verified in the laboratory.

We present simulation results on the influence of grating shapes on diffracted beam profiles for right-angle diffraction. The first-order two-dimensional coupled-mode equations are solved numerically by using the finite-difference method for As(2)S(3) waveguide surface-relief gratings on titanium-indiffused planar waveguides. The simulation results show that square or rectangular gratings result in a distorted profile for the diffracted beam and that truncated grating shapes significantly improve the output beam quality.

A method for measuring the mode-index ratio n of two regions of a planar waveguide with an accuracy of better than 2 in 10(5) is presented. Simple and reliable techniques were utilized to produce two contiguous waveguides, with different refractive indices, on a common substrate. The two waveguiding regions were fabricated both in LiNbO(3) and in BK-7 glass by using titanium indiffusion followed by a proton-exchange (TIPE) process and a two-step Ag(+)/Na(+) ion-exchange technique, respectively. The measured mode-index ratios obtained by our method agreed well with values obtained with the conventional prism-coupling technique.

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.

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.

A multimode integrated optical bistable switch using a LiNbO(3) phase modulator in a noncavity configuration was constructed and tested. Bistability and discriminator operation were observed in this device using a He-Ne laser.