Abstract: An optical amplifier comprising a substrate of a semiconductor material having a pair of opposed surfaces and a body of semiconductor material on one of the surfaces. The body includes a pair of clad layers of opposite conductivity types having an intermediate quantum wall region therebetween. The clad layers are of a semiconductor material which form a heterojunction with the material of the quantum well region. The clad layers and quantum well region forms a waveguide which extends along the body. A gain section is in the body along the waveguide. The gain section includes a capping layer over the outermost clad layer, a contact on the capping layer and a contact on the other surface of the substrate to allow a voltage to be applied across the gain section. The gain section is adapted to generate light in the active region when a voltage is applied thereacross. A light input section having a grating extending across the body is at one end of the gain section.

Abstract: An optical fiber has a beveled end surface and a Bragg reflector grating formed on the end surface to form a single mode reflector for a semiconductor laser. A transmission fiber with a beveled end is fused to the beveled grating to form a continuous transmission line having an internal reflective grating.

Abstract: A phase-locked semiconductor laser array is dephased-locked by forming at least two p-type contacts electrically isolated from one another coupled to one side of the active region and a single contact layer coupled to the other side of the active region. The same current is applied to two p-type contacts to form a single phase-locked far-field lobe. A different current is applied to one of the two p-type contacts to drive one contact harder than the other to form a dephased multiple lobe beam. An effective aperture at the receiver receives the in-phase single lobe and blocks the multiple lobes to produce a modulation effect at the receiver.

Abstract: Semiconductor devices such as lasers which include a substrate with a channel therein with a clad layer overlying the substrate and filling the channel exhibit irregularities such as terraces in the surface of the clad layer which are detrimental to device performance. These irregularities are substantially eliminated by forming the channel in a surface of a buffer layer greater than about 4 micrometers thick on the substrate and forming the clad layer over the buffer layer and the channel. CW lasers incorporating the principles of the invention exhibit the highest output power in a single spatial mode and maximum output power which have been observed to date.

Abstract: A photodetector includes a cap layer over an absorptive layer with the P-N junction formed in the absorptive layer by diffusion of conductivity modifiers from the cap layer. If this diffusion extends too far into the absorptive layer, the detector is rendered useless. The invention includes a photodetector with a buffer layer between the absorptive and cap layers. The concentration of conductivity modifiers is substantially constant in the cap layer, decreases with distance in the buffer layer from the cap layer and extends into the absorptive layer. The invention also includes a method of making this device which includes the steps of forming a buffer layer over the absorptive layer, forming a cap layer over the buffer layer and diffusing the opposite type conductivity modifiers from the cap layer into the buffer and absorptive layers.

Abstract: The invention comprises an improved optical recording medium and information record wherein the light sensitive layer comprises a tracking layer having one or more openings extending therethrough and an absorber layer overlying the tracking layer and the openings therein thereby forming first and second regions of the light sensitive layer having different reflectivities which can be used to provide radial tracking information.The method of the invention includes the steps of depositing a tracking layer onto a light reflective layer, forming one or more openings through the tracking layer and depositing an absorber layer over the tracking layer and into the openings therein.

Abstract: The invention is an improved buried heterostructure laser wherein the improvement comprises a cladding layer which is interposed between the mesa and the burying region and has a refractive index less than that of the burying region and the effective refractive index of the fundamental transverse mode. The discrimination against higher order modes of propagation provided by the structure permits the use of a wider active layer and thus a larger emitting area.

Abstract: An improved overcoated optical recording medium comprises a light absorptive layer and an overcoat overlying the absorptive layer wherein the overcoat has a plurality of indentations in the surface which contacts the absorptive layer thereby forming a first region of the recording medium wherein the overcoat layer does not contact the absorptive layer and a second region wherein the overcoat layer does contact the absorptive layer. The recording sensitivity in the first region is greater since the heat loss to the overcoat layer in these regions is reduced and the mechanical constraints on the formation of deformations in the absorptive layer are relaxed. The invention also includes an improved information record having information recorded in a portion of the first region as a change in the local optical properties.

Abstract: A thin plate of III-V direct-bandgap semiconductor, preferably with anti-reflective coatings, operates as superior optical filter for light having a wavelength which exceeds a given wavelength in the visible or infra-red spectrum. Such a filter is particularly suitable for use in a duplex optical communication system employing a fiber-optic transmission line.

Abstract: In an optical memory device, such as an optical video disk, an injection laser is used as the source of the light, as the detector of the light reflected from the memory element and as the detector for controlling the proper focus of the light on the memory element. The light reflected from the memory element is fed back into the injection laser and variations in certain characteristics of the injection laser, such as the optical output at constant current, the electrical current through the laser at constant voltage and the voltage drop across the laser at constant current, are used to read the memory device and to maintain the focus.

Abstract: A light emitting diode includes a substrate having a body of single crystalline semiconductor material, preferably a Group III-V compound or alloy thereof, on a surface of the substrate. The body includes a window layer directly on the substrate and one or more other layers on the window layer. The layers of the body are of appropriate conductivety types to form a recombination region in which light can be generated. The substrate has an opening therethrough to the window layer. The window layer is of a material which is substantially transparent to the light generated in the recombination region and is of a thickness, 15 to 30 microns, to provide rigidity to the diode.

Abstract: A thin plate of III-V direct-bandgap semiconductor, preferably with anti-reflective coatings, operates as superior optical filter for light having a wavelength which exceeds a given wavelength in the visible or infra-red spectrum. Such a filter is particularly suitable for use in a duplex optical communication system employing a fiber-optic transmission line.

Abstract: An injection laser diode is at one end of an optical fiber to direct modulated optical radiation into the fiber. At the other end of the fiber is a detector, such as a semiconductor photodetector, for the modulated radiation. Between the other end of the optical fiber and the detector is a reflecting shutter which is adapted to periodically reflect some of the radiation, at a lower frequency rate, back along the optical fiber to the injection laser. The radiation reflected back into the injection laser causes a variation in the characteristics of the laser so that the laser operates as a detector for the reflected radiation.

Abstract: A new low cost high efficiency gallium arsenide homojunction solar cell incorporating a passivating surface layer of indium gallium phosphide. The thickness of the indium gallium phosphide layer is selected so that it is transmissive to photons having wavelengths shorter than its bandgap energy.

Abstract: A body of semiconductor material of an injection laser device, capable of operating at a power level up to a few milliwatts per micrometer of emitting width, has two opposed facet surfaces. On at least one of the facet surfaces is a protection layer of an insulating material having an optical thickness equal to approximately one-half the vacuum wavelength of the optical radiation emitted by the device.

Abstract: A reflector of optical radiation is on at least one radiation emitting facet of an electroluminescent device. The reflector includes a plurality of contiguous layers of alternating composition. The layers are of silicon and a material selected from the group consisting of aluminum oxide, magnesium fluoride and silicon dioxide. Each of the layers is approximately .lambda./4n in thickness where ".lambda." is the free space wavelength of radiation emitted from the electroluminescent device, and "n" is the index of refraction of the layer. Two of the alternating contiguous layers provide a reflector which is partially reflecting, while six of the layers provide a reflector substantially reflecting to optical radiation.

Abstract: A thin layer of semiconductor material with an extremely smooth surface can be grown on a substrate by liquid phase epitaxy. When the growing solution contacts the surface of the substrate, the substrate is at a lower temperature than the solution. The temperature difference should be less than 1.degree. C and depends upon the desired degree of smoothness. Both the substrate and the solution are then cooled to permit deposition of the layer.

Abstract: A body of semiconductor material has opposed end surfaces, opposed side surfaces extending to the end surfaces and opposed first and second contact surfaces which are substantially perpendicular to the end and side surfaces. The body includes a substrate having on a surface thereof a mesa shaped active region which extends to the first contact surface. The active region has side surfaces which are spaced from the side surfaces of the body. Also on the substrate are passive regions which extend from the side surfaces of the active region to the first contact surface and side surfaces of the body. The active region has a P-N junction therein. The passive regions each include a plurality of contiguous passive layers having, P-N junctions therebetween. The P-N junctions of the passive regions extend from the first contact surface to the side surface of the body. Metallic electrodes are on each of the contact surfaces. The passive regions serve to restrict current flow to the active region.

Abstract: A body of single crystalline semiconductor material has a first region of one conductivity type spaced from a second region of an opposite conductivity type with a third region between and contiguous to each of the first and second regions. The junctions between the third and each of the first and second regions are heterojunctions. At the peak emission wavelength of the third region the index of refraction of each of the first and second regions is at least 3% less than the index of refraction of the third region. Furthermore, each of the first and second regions has an energy band gap greater than that of the third region, with the difference in the energy band gap being greater than 0.1 eV. The thickness of the third region between heterojunctions is less than 0.125 microns.

Abstract: A substrate of single crystalline gallium arsenide has on a surface thereof a layer of single crystalline indium gallium phosphide. A layer of single crystalline gallium arsenide is on the indium gallium phosphide layer and a work function reducing material is on the gallium arsenide layer. The substrate has an opening therethrough exposing a portion of the indium gallium phosphide layer.