Abstract: An LED in which the recombination region is comprised of a first layer which is degenerately doped (.apprxeq.10.sup.19 /cm.sup.3) and a second layer which is less degenerately doped (.apprxeq.3.times.10.sup.18 /cm.sup.3). The reduced doping of the second layer provides a depletion region which is wider than the depletion region of conventional LED's whereby carrier tunneling (and non-radiative recombination from such tunneling) is reduced. The second layer is only as thick as necessary (.apprxeq.150A) to reduce tunneling (excess current) significantly which permits substantial radiation by improved carrier injection into the first (heavily doped) portion. The heavy doping of the first layer allows the LED to respond very quickly to switching signals whereby improved light output is achieved with a great reduction in non-radiative recombination due to tunneling.

Abstract: A heterojunction laser in which single longitudinal mode operation is achieved by heavily doping the active region of the laser. The dopent density should be approximately 10.sup.19 /cm.sup.3 when the dopent is zinc. A doping density as heavy as possible should be used when the dopent is germanium or any other acceptor impurity. The heavy doping density of the active region excludes the injection of holes into the active region and that exclusion results in single longitudinal mode operation.

Abstract: A diode laser having an active region which has a section in the shape of a closed loop or ring, with the path length of the loop or ring causing a light wave traveling completely around the loop or ring section from a coupler section of the active region to undergo a phase shift of 180.degree. relative to its starting phase whereby the two waves interfere destructively, and thus provide optical feedback.

Abstract: A semiconductor device which utilizes interferometric principles and electrical control to provide either light reflection or light transmission or partial light reflection/transmission. In a preferred embodiment, the device includes an input waveguide which divides into branch waveguides, with the branch waveguides being reunited at an output waveguide. When the optical path lengths of the branched waveguides varies by an integer multiple of the light wavelength in the guides, the light waves interfere constructively at the output waveguide causing light to be transmitted into the output waveguide. When the light wave in one branch waveguide undergoes a single pass phase shift of 180.degree. relative to the light wave in the other branch waveguide, the light waves interfere at the output waveguide and are caused to return to the input waveguide through the branch waveguides. The returning light wave in the one branch waveguide once again experiences a single pass 180.degree.

Abstract: A method of making a diode laser in which a pump current confining channel is formed on the substrate side of a diode laser prior to growth of the active or recombination region of the diode laser. The current confining channel is formed by providing, by diffusion, a rectifying junction on a substrate surface and then forming, by etching, a narrow channel completely through a central portion of the diffused layer and the rectifying junction. The remaining layers of the diode laser are then successively grown. The portions of the rectifying junction on both sides of the channel are reverse biased when the primary junction of the diode laser is forward biased whereby pump current flow is confined to a path through the channel.

Abstract: A heterojunction diode laser which achieves transverse mode control by providing adjacent to the active region layer of the laser a layer having a thickness substantially less than the thickness of the active region layer and of a material having a bandgap higher than the bandgap of the material of the active region layer. All transverse modes have increased penetration into a lossy substrate via the thin layer with the loss being least for the lowest order mode such that only the lowest order mode can be made to lase at low pumping current levels.

Abstract: A heterojunction diode laser which utilizes leaky wave coupling through a thin confining layer or a pair of thin confining layers to produce a high powered, highly collimated output beam with high external differential quantum efficiency, and relative freedom from facet damage resulting from high optical density.

Abstract: An electrically pumped distributed feedback grating coupled diode laser having an optical cavity containing two closely spaced layers, a first of the layers is electrically pumped and the second of the layers is corrugated. Optical wavelength radiation and amplification of said radiation is generated in the first layer by carrier recombination with the radiation spreading to the second layer for coherent reflection by the corrugation and for low loss transmission. Carrier confinement in the first layer and optical confinement in the optical cavity are achieved by surrounding each of these layers by materials having a higher bandgap and lower index of refraction than the materials of the first and the second layers. The corrugation of the second layer can extend over only a portion of the length of the second layer such that the uncorrugated portion of the second layer provides a low loss waveguide.

Abstract: A method of making a buried-heterostructure (BH) diode injection laser capable of operating at low room temperature thresholds and in the lowest order TE, TM, or TEM modes. Following formation of a pump current confining layer in a substrate, an elongated groove or channel is formed in the substrate with the groove extending through the pump current confining layer. A first light guiding and carrier confining layer, an active layer, and a second light guiding and carrier confining layer are then grown successively on the grooved surface of the substrate with the active layer material having both a higher index of refraction and lower bandgap than the material(s) of the light guiding and carrier confining layers.

Abstract: An electrically pumped, solid-state laser device having a grating or physical periodic structure in a region, or adjacent a region, of semiconductor material that functions as a light wave guide. The spacing of the perturbations of the periodic structure are selected to be an integer number of half wavelengths of the desired laser wavelength. The electrically pumped, solid-state laser device can be a single heterojunction device or a double heterojunction device. Both devices are formed by a process which provides for formation of the periodic structure prior to formation of the light guiding layer or region. Due to this process a periodic structure having a desired spacing and substantial depth is produced, which structure produces Bragg Scattering which couples and reinforces light traveling through the light guiding layer in both directions in a coherent manner such that reflections are in phase, thus allowing laser operation in the absence of discrete end reflectors.This is a division of application Ser.

Abstract: A heterojunction diode laser which produces a highly collimated, polarized light beam perpendicular to the plane of the PN junction of the laser rather than through cleaved end faces in the plane of the PN junction. The diode laser includes a periodic structure which is buried at a heterojunction interface and in contact with a light waveguide layer. The periodic structure acts to produce the feedback necessary for lasing. If the spacing of the teeth of the periodic structure are an integer number of wavelengths of the light photons produced in the laser, the light beam exits at an angle perpendicular to the plane of the PN junction. If a tooth spacing is chosen that is not equal to an integer number of wavelengths of the light photons produced in the laser, the light beam may emerge from the diode at an angle other than the normal with the specific angle determined by the particular tooth spacing.

Abstract: A laser having layers of a first material interleaved with layers of a second material with the first material having a different index of refraction and bandgap than those of the second material. The thicknesses of the layers of the first and second materials satisfy the relationship t = m .lambda./2n where m is the laser mode and n is the index of refraction of the material, such that the right and left going waves of the light produced by the layers of the first material when the laser is pumped are coupled and reinforced in a coherent manner by the layers of the second material such that reflections from the second material are in phase, thus allowing laser operation in the absence of discrete end mirrors.

Abstract: A buried-heterostructure (BH) diode injection laser capable of operating at low room temperature thresholds and in the lowest order TE, TM or TEM modes. The laser has an elongated groove in a substrate with the groove extending through a pump current confining layer with a central portion of the active layer substantially completely within the groove and substantially completely surrounded by light guiding and carrier confining layers of material having a lower index of refraction than the index of refraction of the material of the active layer. The light guiding and carrier confining layer in contact with the substrate has a central depression within the elongated groove and the central portion of the active layer is bowl-shaped and within the depression such that light waves produced by carrier recombination within the central portion of the active layer when the laser is forward biased are guided in the central portion of the active layer such that the laser produces a light beam having reduced width v.

Abstract: A distributed feedback, (DFB) electrically pumped diode laser in which the spacing of the periodic structure within the diode is selected to optimize the interaction between the periodic structure and the electromagnetic waves in the diode laser. The degree to which the waves interact with the periodic structure is described mathematically by a coupling constant K, with larger values of K corresponding to lower gains required to produce laser operation. It is shown that in DFB diode lasers higher order transverse modes have a higher coupling constant K with the periodic structure than does the lowest order transverse mode and thus the higher order transverse modes will lase more easily than the lowest order transverse mode.

Abstract: An electrically pumped, distributed feedback laser having all side surfaces of the active laser medium cleaved and a periodic structure at a 45.degree. angle to all of the cleaved surfaces. Current confining channels restrict pumping current to selected regions of the active laser medium to provide sufficient feedback such that two parallel filamentary areas of the active medium lase. By having multiple lasing filaments the divergence of the output beam in the direction of the width of the filaments is reduced by a factor proportional to the number of filamentary lasing areas.

Abstract: A structure for providing arrays or individual hemispherical diodes and methods of producing the diodes. When the diode array is to be part of a configuration utilizing a substrate, the substrate is selected to have radiation transparency, a lower refractive index, and lattice constant and lattice structure similar to that of a crystal layer grown in hemispheres formed in the substrate. When the diode array is to be removed from the substrate, a material that can be preferentially etched is grown between the hemispheres formed in the substrate and the grown crystal layer that is to have light emitting areas.