Abstract: A quantum well is formed in the active region of a superluminescent diode by limiting the active region to a thickness on the order of the carrier deBroglie wavelength. Increased efficiency of recombination of electrons and holes due to the existence of the quantum well allows operation at threshold currents which are substantially proportional to cavity length. Variation in threshold current with temperature is also reduced.

Abstract: A quantum well is formed in the active region of a superluminescent diode by limiting the active region to a thickness on the order of the carrier deBroglie wavelength. Increased efficiency of recombination of electrons and holes due to the existence of the quantum well allows operation at threshold currents which are substantially proportional to cavity length. Variation in threshold current with temperature is also reduced.

Abstract: A semiconductor light-emitting device structured similarly to an index-guided laser, but having waveguide channels that are formed at a selected small angle of inclination with respect to a direction normal to cleaved facets formed in the structure. The angle of inclination should be at least half the critical beam angle above which total internal reflection will not occur within the waveguide channels. The angled condition of the waveguide channels ensures that effective mirror losses at the facets exceed the modal gain of the device, so that lasing will not occur, even when the current and power are increased to high levels. The device produces up to 30 mW or more of output power at a large spectral bandwidth and small coherence length.

Abstract: A superluminescent light-emitting diode in which the spectral width of the output increases with increasing optical output power, thereby allowing the generation of high optical output powers with a broad frequency spectrum that is desirable for some applications of the superluminescent diodes. This desirable characteristic is obtained by structuring the diode to produce a non-uniform gain profile across its active layer. Alternative approaches for achieving the non-uniform gain profile include varying the thickness of the active layer, and varying the current density by employing an asymmetrical channel configuration or an asymmetrical electrical contact strip.

Abstract: A semiconductor laser diode structure operable at high power and brightness levels and having a relatively low threshold current, high efficiency, good mode stability, and reduced temperature sensitivity. The disclosed embodiments have twin parallel channels formed in a p type substrate, and employ an n type blocking layer to confine current to a region between and including the channels. The structure includes first and second inactive cladding layers, and an active layer forming a diode junction. The first or lower inactive layer is thinner in the region between the channels, and this results in a higher forward-bias voltage at the center of the active layer, thereby focusing the current near the central position. This current focusing mechanism, which is enhanced by the optional use of a curved active layer, results in the improved characteristics of the structure.

Abstract: A semiconductor laser array structure operable at relatively high powers and high brightness levels compared with prior laser arrays. At least two principal lasing regions are formed in a single active layer of the structure, and are closely coupled by an intermediate region in which there is optical gain. Preferably, the dimensions of the structure are selected to provide single-filament lasing in the principal lasing regions and in the intermediate region, resulting in a composite output that is apparently phase-locked and has a high-brightness, single-lobe far-field radiation distribution pattern with a low divergence angle. The disclosed structure uses gallium arsenide and gallium aluminum arsenide materials and is fabricated using liquid-phase epitaxy. Longitudinal mode selection in the device may be accomplished by configuring the two channels to produce different sets of longitudinal modes, the close coupling of the two regions resulting in the output of only those modes common to both regions.

Abstract: Alternate vanes on the valve of a rotary feeder for feeding particulate material effect clearances with the surrounding feeder housing surface to effect desired, controlled flow of the particulate material. The clearances between the alternate vanes and the housing may comprise a variety of forms such as notches disposed in the alternate vane distal edges. Also, the radial length of the alternate vanes may be shortened to effect the desired clearances. Such clearances also greatly increase the permissible feeding rates.