Abstract: An electrically tunable interference filter comprises a semiconductor body which has a plurality of semiconductor layers. Each semiconductor layer comprises first and second sublayers which together define a heterojunction and first and second portions which together define a pn junction located at or closely adjacent to the heterojunction. Electrical contacts are provided for biasing the pn junctions. Application of a forward bias to some of the pn junctions causes injection of carriers from the second sublayers across the heterojunctions into the first sublayers to modify the refractive index of the first sublayers. Application of a reverse bias to other of the pn junctions enhances an inherent electric field at the pn junctions to modify the refractive indices of regions adjacent to the pn junctions. The applied reverse bias also depletes carriers from regions of the first and second sublayers to modify the refractive indices of those regions.

Abstract: A surface-emitting, light emitting device has a columnar active region of one direct bandgap semiconductor and an adjacent confining region of higher bandgap semiconductor. Contacts are made to the active and confining regions and a window is formed in the device in vertical alignment with the active region to permit light emission from the device. The semiconductors are doped to establish a pn junction within a carrier diffusion length of the heterojunction between the active and confining regions, the pn junction extending the length of the active region. In use, laser light is emitted along the axis of the columnar active region in response to current passing across the pn junction. The active region is epitaxially grown with a compositional and refractive index periodicity causing Bragg distributed feedback (DFB) laser operation, the bandgap of the material of the confining region being higher than that of all the layers in the active region.

Abstract: A surface-emitting, light emitting device has a columnar active region of one direct bandgap semiconductor and an adjacent confining region of higher bandgap semiconductor. Contacts are made to the active and confining regions and a window is formed in the device in vertical alignment with the active region to permit light emission from the device. The semiconductors are doped to establish a pn junction within a carrier diffusion length of the heterojunction between the active and confining regions, the pn junction extending the length of the active region. In use, laser light is emitted along the axis of the columnar active region in response to current passing across the pn junction. The confining region is epitaxially grown with a compositional and refractive index periodicity causing Bragg distributed feedback (DFB) laser operation.

Abstract: A surface-emitting, light emitting device has a columnar active region of one direct bandgap semiconductor and a surrounding confining region of a higher bandgap semiconductor. Contacts are made to the active and confining regions and a window is formed in the device in alignment with the active region to permit light emission from the device. The semiconductors are doped to establish a pn junction within a carrier diffusion length of the heterojunction between the active and confining regions, the pn junction extending the length of the active region. In use, light is emitted along the axis of the columnar active region in response to current passing radially across the pn junction.

Abstract: An improved melt dispensing liquid phase epitaxy (LPE) boat is disclosed. It comprises two separable compartments. A supply-melt reservoir and a growth-melt bin separable by means of a separation slider for separating the two compartments prior to the actual process of epitaxial growth. In a further improvement, the substrate holder has a melt collection bin for receiving used growth-melt.