Abstract: An optical image correlator includes a photorefractive medium for recording an interference pattern that corresponds to the Fourier transform of an input image or the multiplicative product of the Fourier transforms of two respective input images. In contrast to correlators of the prior art, the correlator described here includes a semi-insulating, multiple quantum well device as the photorefractive medium.

Abstract: A spatial light modulator includes a multiple quantum well (MQW) device. Unlike MQWs of the prior art, this MQW is made semi-insulating. As a result, individual picture elements can be defined entirely by the placement of electrodes in an array on a surface of the device. Them is no need to etch trenches for electrical isolation of the picture elements.

Abstract: Absorption properties of an optically active medium can be changed drastically by a Fabry-Perot microcavity. Optically active medium of the cavity includes a host material which is not optically active and at least one rare earth ion which provides optical activity to the medium. The Fabry-Perot cavity is designed to be resonant with excitation wavelength of an absorption band of the host material. The excitation is provided by a source of radiation positioned such that the radiation impinges on the cavity at an angle within a range of from zero to less than 90 degrees from the normal to the top surface of the cavity. In one embodiment Er-implanted SiO.sub.2 is used as the optically active medium. SiO.sub.2 :Er has an absorption band at 980 nm and an emission band at 1.55 .mu.m due to 4f intra-atomic transitions of Er.sup.3+ ions. The Fabry-Perot cavity is designed to be resonant with the 980 nm absorption band of SiO.sub.2 :Er.

Abstract: The use of alternating n and p type regions asymmetrically spaced in a semiconductor material yields extremely advantageous properties. In particular, by controlling the doping level and the spatial configuration of the doped region both the device response and its optical properties are controllable. Therefore, in applications such as those involving optical switches LEDs, lasers and long wavelength detectors, both the speed of device and its optical properties are controllable. As a result, greater fabrication flexibility than previously available is possible.

Abstract: An electro-optic medium, useful for image processing, is formed by creating a distribution of deep impurity levels over essentially all the lateral extent of a multilayer heterostructure. This treatment renders the heterostructure semi-insulating, and as a consequence, individual image-resolution elements are isolated. Described is an optical system comprising such an electro-optic medium.

Abstract: The use of alternating n and p type regions asymmetrically spaced in a semiconductor material yields extremely advantageous properties. In particular, by controlling the doping level and the spatial configuration of the doped region both the device response and its optical properties are controllable. Therefore, in applications such as those involving optical switches LEDs, lasers and long wavelength detectors, both the speed of device and its optical properties are controllable. As a result, greater fabrication flexibility than previously available is possible.

Abstract: Semi-insulating wafers such as semi-insulating gallium arsenide wafers are commonly utilized in the fabrication of semiconductor devices, e.g., lasers and optical detectors. The quality of wafer electrical properties is determined before device processing by an optical technique. In this technique a refractive index change is induced with incident light and the rate of decay of this refractive index change upon change of incident light intensity is monitored with a second beam. The rate of decay is directly related to electrical properties such as resistivity. Subsequent processing is then based on this measurement.

Abstract: An integrated optical device is disclosed which includes an integral photodetector exhibiting picosecond response times and quantum efficiences greater than about 30 percent. The photodetector includes a region of substantially amorphous semiconductor material interposed between two electrodes, with the electrode spacing being comparable to the average electron trapping length in the material between the electrodes. Preferably, at least one of the electrodes is a microstrip transmission line.

Abstract: An optical processor is formed by utilizing a doped electrooptic semiconductor material. By making information in the form of light incident on the crystal, a refractive index change is effected. This information, in the form of a refractive index change, is then read utilizing a second light source.

Abstract: A photoelectrochemical etching process is described for producing gratings in various semiconductors. Because this is a direct, single step process, extreme uniformity is obtained over a wide area. The procedure is particularly useful for mode reflection in distributed feedback lasers.

Abstract: A photodetector, and a method for detecting electromagnetic radiation, is disclosed. The photodetector includes a body which undergoes a detectable, internal physical or chemical change when exposed to electromagnetic radiation, as well as means for detecting this change. The photodetector also includes a substantially periodic surface which increases the efficiency with which incident electromagnetic radiation is coupled onto the photodetector.

Abstract: A photodetector, and a method for detecting electromagnetic radiation, is disclosed. The photodetector includes a body which undergoes a detectable, internal physical or chemical change when exposed to electromagnetic radiation, as well as means for detecting this change. The photodetector also includes a substantially periodic surface which increases the efficiency with which incident electromagnetic radiation is coupled onto the photodetector.

Abstract: A means for aligning components of an optical system without the use of conventional optical equipment is disclosed. This means includes the use of a pair of electrodes in proximity with the light guiding portion of a pyroelectric system element. The absorption of light in the waveguide produces a current in the pyroelectric material tht is monitored at the electrodes. Alignment of the system components is achieved by adjusting their relative position to increase the monitored signal.

Abstract: A means for aligning components of an optical system without the use of conventional optical equipment is disclosed. This means includes the use of a pair of electrodes in proximity with the light guiding portion of a pyroelectric system element. The absorption of light in the waveguide produces a current in the pyroelectric material that is monitored at the electrodes. Alignment of the system components is achieved by adjusting their relative position to increase the monitored signal.

Abstract: Amorphous niobates and tantalates of the alkali metals lithium, potassium, and sodium which may be off-stoichiometric with regard to the related octahedrally coordinated crystalline compositions manifest high values of dielectric constant and ionic conductivity. Electrode bearing devices may be utilized, inter alia, as capacitors, electrolytic cells, and bolometers.