Abstract: High power edge emitting semiconductor lasers are formed to emit with very narrow spectral width at precisely selected wavelengths. An epitaxial structure is grown on a semiconductor substrate, e.g., GaAs, and includes an active region at which light emission occurs, upper and lower confinement layers and upper and lower cladding layers. A distributed feedback grating is formed in an aluminum free section of the upper confinement layer to act upon the light generated in the active region to produce lasing action and emission of light from an edge face of the semiconductor laser. Such devices are well suited to being formed to provide a wide stripe, e.g., in the range of 50 to 100 &mgr;m or more, and high power, in the 1 watt range, at wavelengths including visible wavelengths.

Abstract: A semiconductor structure for use as a laser or amplifier has a multilayer structure including a substrate, an active region, optical confinement and cladding layers on each side of the active region to surround the active region. The structure includes at least one core element at which light emission occurs and interelement regions laterally adjacent to the core element with the effective refractive index of the interelement regions higher than that of the core element to provide antiguiding of light emitted in the core element. The optical confinement and cladding layers on opposite sides of the active region have different indexes of refraction to provide an optical waveguiding structure in the transverse direction in the core element which is asymmetrical and which favors lasing only in the fundamental transverse mode.

Abstract: An intersubband quantum box laser structure includes an active structure having a two dimensional array of quantum boxes separated from one another in a semiconductor matrix. The quantum boxes are formed to suppress phonon-assisted transitions, and thus the transitions become primarily of the radiative type. Each quantum box has a multilayer structure including an electron injector, an active region with a quantum well, and an electron mirror. Electrons injected from the injector into the active region at a high energy level relax to a lower energy level with the emission of a photon at, for example, mid-infrared wavelengths. The mirror reflects electrons at the higher energy level at which they were injected and transmits electrons at the lower energy level after emission of a photon. Multiple layers of semiconductor are formed on each side of the active structure to provide conduction across the multiple layer structure and to provide optical confinement of the photons emitted.

Abstract: Semiconductor diode lasers include an aluminum free active region including at least one active layer having a general composition In.sub.(1-x) Ga.sub.x As.sub.y P.sub.(1-y) where 0.ltoreq.y.ltoreq.1; two confinement layers bounding the active region and having a general composition In.sub.(1-x) (Ga.sub.(1-z) Al.sub.z)x P wherein aluminum content z may be zero; and a lower cladding layer, and at least one upper cladding layer adjacent the confinement layers. The cladding layers have the same general composition as the adjacent confinement layer, but always have a finite aluminum content. The aluminum content of the cladding layers is selected such that the cladding layers have a energy bandgap greater than the energy bandgap of the confinement layers.

Abstract: A high power monolithic surface emitting semiconductor laser provides a single lobe far-field radiation profile which is emitted normal to the plane of a surface of the semiconductor laser structure. The semiconductor laser includes an active region layer at which light is emitted and a complex-coupled distributed feedback grating positioned to act upon light from the active region. The adjacent elements of the distributed feedback grating differ from one another in both refractive index and gain/loss. The grating period, or the combined width of the two adjacent grating elements, is selected to be equal to a full wavelength in the semiconductor structure of the light emitted from the active region.

Abstract: A semiconductor laser is formed with an array of a small number (two to ten) antiguide elements each containing a portion of the active region of the semiconductor laser. Interelement structures between the antiguide elements are formed to have a relatively high interelement loss coefficient (at least 100 cm.sup.-1), providing excellent discrimination between the resonant in-phase mode and the unwanted nonresonant modes. Lateral reflectors may be utilized at the edge of the array to reflect light back to the array, but are not necessary when the antiguide elements are sufficiently wide and the effective index step between the antiguide elements and interelement structures is sufficiently large. Because only a relatively small number (10 or less) of antiguide elements are utilized, fabrication tolerances are relatively large and practical devices may be produced with satisfactory yields.

Abstract: This invention discloses a semiconductor laser incorporating a plurality of resonant optical waveguide array cells. In each of the resonant optical waveguide array cells, leaky waveguide elements are coupled together such that radiation leaked from one antiguide element is coupled with radiation propagating along another antiguide element across an interelement region. As the radiation propagates through the array it is reflected at each end of the array until it builds up enough optical gain to reach lasing threshold. Then, radiation is leaked from the sides of each array such that this radiation can impinge other resonant optical waveguide arrays and be coupled with these arrays in phase to develop a laser beam having a higher intensity than can be achieved with a single array semiconductor laser.

Abstract: A high-power semiconductor laser diode that employs a lateral antiresonant reflecting optical waveguide for generating a single-mode laser beam having an aperture spot size on the order of 4 to 8 microns. The lateral antiresonant reflecting optical waveguide is a negative-index waveguide or antiguide that operates in an antiresonance condition for the fundamental lateral mode, but not for the higher-order lateral modes. Consequently, the fundamental lateral mode is reflected by the lateral waveguide while the higher-order lateral modes are allowed to leak out. This provides strong discrimination between the fundamental lateral mode and the higher-order lateral modes in order to generate a single-mode laser beam having a large aperture spot size. The lateral waveguide also provides good lateral mode stability due to the large negative step in the waveguide index of refraction.

Abstract: Device coherency and optical-mode stability are obtained in light sources having large apertures and output powers, by using an important property of arrays of antiguides or negative-index waveguides. One embodiment of the invention is a power amplifier into which a light beam is input from a master oscillator. The input beam is introduced into one or more waveguides of an array, and leaks into successive adjacent waveguides, forming a fan-out pattern as it progresses along the array. The antiguides have an interelement spacing that is selected to produce a resonance effect, as a result of which light is coherently coupled to all waveguides in the array. The structure also provides lateral mode control and assures mode stability of the output. In the amplifier embodiment of the invention, the end faces of the array are antireflective coated and light makes only a single pass through the structure.

Abstract: A semiconductor laser array of antiguides having a large number of antiguide elements to provide relatively high optical power output with a high degree of coherence and array mode discrimination. The antiguide elements are grouped into array cells that are separated by interarray regions having a width and refractive index selected to produce a resonance condition in the 0.degree.-phase-shift array mode. Each array cell is also designed to operate in the resonant condition, and losses in the interarray regions discriminate against modes other than the 0.degree.-phase-shift mode. The entire group of cells operates as a high-power, coherent ensemble, without the degradation of mode discrimination and beam quality usually associated with large numbers of waveguide elements.

Abstract: An array of semiconductor laser diodes having parallel waveguide elements, of which each adjacent pair is coupled together by an X-shaped waveguide junction having a connecting waveguide in which lateral modes are formed as a result of merging of the pair of waveguide elements. The waveguide elements diverge again from the connecting waveguide at an angle great enough to ensure that there are high scattering and radiation losses near the point of divergence of the waveguide elements, for the fundamental mode in the connecting waveguide. If an adjacent pair of waveguide elements operate in phase, this excites the fundamental mode in the connecting waveguide, which is effectively suppressed by the losses that occur near the point of divergence from the connecting waveguide. The structure thereby discriminates against connecting waveguide in an in-phase mode, resulting in operation in the 180.degree.

Abstract: A semiconductor diode laser device, and a related method for its fabrication, the laser being of the type from which light is emitted in a direction perpendicular to planar layers forming the device. The laser includes an active layer and cladding layers formed on a supporting substrate, and a highly reflective semiconductor stack reflector formed on one of the cladding layers. The semiconductor stack reflector may be placed in contact with a heat sink and performs the multiple functions of electrical current conduction, heat removal and light reflection. A current confinement layer is formed laterally surrounding the semiconductor stack reflector, to provide one element of a back-biased junction that confines the current to the reflector region. A dielectric stack reflector is formed in a well in the substrate, and provides for light emission from the device.

Abstract: A semiconductor laser array with features providing good beam quality at high powers, first by employing a laterally unguided diffraction region in which light from a set of waveguides is re-imaged in accordance with the Talbot effect and two arrays of waveguides may be used to provide a spatial filtering effect to select a desired array mode. This provides a laser array with increased power per unit solid angle, and with additional advantages of ability to scale the device up to larger arrays, ability to control the electrical excitation of the device for better optimization, and improved modal discrimination. A second aspect of the invention is the use of a resonance condition in an antiguide array, to produce a uniform near-field intensity pattern and improved coupling and device coherence.

Abstract: A semiconductor laser diode array structure in which interelement losses are deliberately included, to favor operation at higher-order array modes of operation, and thereby avoid the disadvantage of beam broadening that results when lower-order array modes of operation are used at very high drive currents. To provide a desirable far-field radiation pattern, the structure includes a wide-waveguide interferometric configuration to select only the lowest of the higher-order modes. The desired interelement losses are obtained in the illustrative embodiment by a buffer layer that provides antiguiding in a transverse direction, but only in the interelement regions. The buffer layer is transparent, for strong interelement coupling and stability of operation. The illustrative embodiment was operated at drive currents in excess of four times threshold current, and with beam broadening only slightly above the diffraction limit.

Abstract: A semiconductor laser diode array in which the lasing elements are formed as parallel negative-index waveguides, to provide operation at higher powers and in one of two stable array modes. Lasing in interelement regions, between the lasing elements, is suppressed by the inherently low transverse optical confinement factor provided by high-index semiconductor material in the interelement regions, and may be further suppressed by the use of an active layer that extends only through the lasing elements and not through the interelement regions. A desired array mode may be selected by the use of a structure favoring 0.degree.-phase-shift array modes, such as a wide-waveguide interferometric structure. Both liquid-phase epitaxy (LPE) and metalorganic chemical vapor deposition (MOCVD) processes may be used in fabrication of the device.

Abstract: A semiconductor laser array that discriminates in favor of a fundamental array mode of oscillation and provides a far-field radiation pattern that is single lobed and diffraction-limited. The array includes a first set of parallel waveguides, a wide-waveguide section and a second set of parallel waveguides. Oscillation in the fundamental or 0.degree.-phase-shift array mode is easily coupled from the first set of waveguides to the wide-waveguide section, and from the wide-waveguide section to the second set of waveguides. When adjacent waveguides oscillate out of phase, as in the 180.degree.-phase-shift array mode, easy coupling is not obtained because the waveguides of the second set are not colinear with those of the first set. The structure of the invention also avoids the large radiation losses inherent in Y-junction arrays.

Abstract: A phase-locked semiconductor laser array having a plurality of lasing regions includes phase-shifting means on the emitting surface thereof through which laser light is emitted. The phase-shifting means provide a phase shift for those laser beams passing therethrough so that the phases of all the emitted laser beams are substantially the same. The phase-shifting means include a coating on the emitting surface which has a spatially varying thickness in the lateral direction.

Abstract: A phase-locked laser array comprises a substrate with two spaced-apart pluralities of channels extending towards different reflecting surfaces of the array. The axes of symmetry of the channels of one plurality are offset from the axes of symmetry of the channels of the second plurality. Coupling of light propagating in the optical waveguides over one plurality of channels into the waveguides over the second plurality of channels induces a zero phase difference between the laser oscillations of adjacent channels.

Abstract: The present invention is a semiconductor diode laser array which favors oscillation in the zero degree phase shift mode. The array comprises first and second sets of waveguides which are interdigitated in a coupling region. Energy transfer between the first and second sets of waveguides by way of evanescent coupling is needed to define the feedback paths for sustaining laser oscillations in the waveguides. Such coupling is optimum and the threshold current for lasing lowest when all of the waveguides in both sets oscillate in phase.

Abstract: A phase-locked laser array comprises a body of semiconductor material having means for defining a plurality of substantially parallel lasing zones which are spaced an effective distance apart so that the modes of the adjacent lasing zones are phase-locked to one another. One of the array electrodes comprises a plurality of electrical contacts to the body between the lasing zones. These contacts provide an enhanced current density profile and thus an increase in the gain in the regions between the lasing zones so that zero degree phase-shift operation between adjacent lasing zones is achievable.