Abstract: A single-stage dielectric band elimination filter has a dielectric block with its outer surfaces mostly covered by an outer conductor and two mutually coupled resonant lines formed therein. Each resonant line has an open end insulated from the outer conductor and a shorted end connected thereto, the open and shorted ends of the two resonant lines being oppositely oriented. A multi-stage dielectric filter has a plurality of such single-stage band elimination filters formed inside a dielectric block, each mutually adjacent pair of the single-stage band elimination filters being interdigitally coupled or combline-coupled to each other with phase shift of II/2 therebetween. The open end of a resonant line may be formed at one of the end surfaces of the dielectric block, being connected to an electrode insulated from the outer conductor, or at an annular conductor-free area formed on the inner surface of the corresponding throughhole.

Abstract: A dielectric filter has a stepped resonator hole and straight resonator holes. A portion of a short-circuited end surface of the dielectric block, corresponding to a resonator formed in the stepped resonator hole, is removed, so that the short-circuited end surface has a stepped shape defined by a step surface. Thus the stepped resonator is shorter than the straight resonators. It is thus possible to provide a filter in which the respective resonant frequencies of the resonators are substantially the same, and inner conductor-free portions in the stepped hole and straight holes may be formed at substantially the same distances from an open-circuited end surface, while still obtaining firm coupling between the resonators.

Abstract: Resonator holes are formed extending one to the other of a pair of opposing end surfaces of a dielectric block, and inner conductors are formed on inner peripheral surfaces of resonator holes respectively. On an outer surface of dielectric block, a pair of input/output electrodes and one antennal electrode are formed, and expect these regions, an outer conductor is formed. By the coupling of two resonators corresponding to the resonator holes, a transmitting filter is provided, and by two resonators corresponding to resonator holes, a receiving filter is formed.

Abstract: In a semiconductor laser module wherein a semiconductor laser chip having a light emitting facet and an optical fiber having a fiber facet are mounted on a module substrate so that the light emitting facet faces the fiber facet, the semiconductor laser chip includes semiconductor layers disposed on a semiconductor substrate and including a light emitting region, and the semiconductor substrate has a portion protruding beyond the light emitting facet. The optical fiber includes a core extending in the optical waveguide direction and a cladding part surrounding the core. In this module, positioning of the optical fiber in the optical axis direction is performed by abutting a portion of the cladding part at the fiber facet against the protruding portion of the substrate of the semiconductor laser chip.

Abstract: A method of fabricating an integrated semiconductor laser device includes preparing a polygonal heat sink having side surfaces, and die-bonding semiconductor laser chips to the side surfaces of the heat sink. Therefore, the semiconductor laser chips are accurately arranged at such positions that laser beams emitted from these laser chips are parallel to each other and partially overlap each other. In addition, the semiconductor laser chips are integrated without unwanted contact of a conductive material used for the die-bonding to an active layer exposed at a facet of each laser chip. Further, since the complicated process of die-bonding a laser chip on another laser chip is dispensed with, the fabricating method is easily automated.

Abstract: A compact dielectric band elimination filter, which is composed of fewer components and can be produced in fewer production steps, uses a resonator apparatus having a dielectric block with a plurality of throughholes each containing an inner conductor and serving as a resonator. Capacitor electrodes are formed on a main surface of the block such that series-connected resonant capacitors are provided with the inner conductors inside the throughholes. The resonator apparatus is mounted on a substrate of a layered structure having an inductor thereon.

Abstract: A dielectric block having an external conductor on the outer surface and a plurality of holes with internal conductors formed therein; no internal conductors are provided near one end of each of the plurality of holes. Portions of the dielectric block and the external conductor are removed so as to obtain a dielectric resonator having desired resonator characteristics. In another embodiment, portions of the dielectric block are removed so as to bring the external conductor closer to the internal conductors thereby obtaining a dielectric resonator resonant with a desired frequency. The dielectric resonators limit leakage of electromagnetic field and do not require additional parts such as terminals and case.

Abstract: A dielectric resonator apparatus includes at least one dielectric coaxial resonator in a dielectric block of a dielectric material having first and second end surfaces, and a plurality of side surfaces. At least one cylindrical resonator hole is disposed so as to penetrate the dielectric block and an outer conductor is disposed on at least the first end surface and, the plurality of side surfaces. Further, at least one inner conductor is disposed in the resonator hole so that one end thereof located on the first end surface side is electrically insulated from the outer conductor, thereby constituting at least one dielectric coaxial resonator. A pair of input and output electrodes is disposed on at least one predetermined side surface of the dielectric block so as to be electrically insulated from the outer conductor and to be close to one end of the inner conductor located adjacent the first end surface.

Abstract: In a dielectric block, resonator holes have steps thereby providing a portion having a larger inner diameter and a portion having a smaller inner diameter, and the smaller inner diameter portion of each resonator hole is formed on the side of a short-circuited end surface. By forming the small inner diameter portions of the resonator holes relatively close to each other, the coupling between the two resonators becomes inductive coupling. By contrast, when small inner diameter portions are formed further apart from each other, the coupling between the two resonators becomes capacitive coupling. The coupling strength can be changed by adjusting the distance between the small inner diameter portions.

Abstract: A method for fabricating a semiconductor laser includes forming a double heterojunction structure on a first conductivity type semiconductor substrate; forming the double heterojunction structure into a stripe mesa shape by selective etching; successively growing a first conductivity type layer, a second conductivity type current blocking layer, and a first conductivity type current blocking layer on opposite sides of the mesa to embed the mesa; and adding an impurity from a surface of the first conductivity type current blocking layer to form impurity doped regions that electrically separate the second conductivity type current blocking layer from an upper part of the mesa at opposite sides of the mesa.

Abstract: A dielectric resonant component includes at least one dielectric multistage resonator including one dielectric block, a plurality of inner conductor formation holes formed in the one dielectric block, an inner conductor formed on an inner surface of each of the inner conductor formation holes, and an outer conductor covering a substantially entire outer surface of the one dielectric block, the dielectric multistage resonator constituting a plurality of dielectric resonators in the one dielectric block; and a mount substrate fixedly mounted on the dielectric multistage resonator, for transmitting a signal transmission between each of the dielectric resonators of the dielectric multistage resonator and an external circuit board, when the dielectric resonant component is mounted on the external circuit board.

Abstract: A compact dielectric resonator apparatus is comprised of a dielectric block having a plurality of mutually parallel throughholes formed therethrough with inner surfaces covered with a conductive film so as to provide coaxial resonators. The degree of coupling between a mutually adjacent pair of such dielectric resonators can be adjusted by forming grooves, a bottomed hole or a slit or burying a conductive plate therebetween in the dielectric block, and varying physical characteristics of such grooves, bottomed hole, slit and/or conductive plate, without changing the separations between the throughholes or the external dimensions of the dielectric block.

Abstract: A dielectric resonator apparatus comprising a plurality of dielectric coaxial resonators has a dielectric block with first and second surfaces and a plurality of side surfaces located therebetween, and a plurality of cylindrical resonator holes are formed in parallel to each other so as to penetrate the dielectric block, each of the resonator holes having an opening at the first surface and another opening at the second surface. Further, an outer conductor is formed on the first and second surfaces and a plurality of side surfaces, and a plurality of inner conductors is formed on the plurality of resonator holes, respectively.

Abstract: A semiconductor laser device including a semiconductor substrate; a plurality of semiconductor layers including an AlGaAs layer epitaxially grown on said semiconductor substrate; a ridge having a reverse mesa shape and opposed sides formed of said plurality of semiconductor layers; an Al.sub.x Ga.sub.1-x As low temperature buffer layer (0.ltoreq..times..ltoreq.1) disposed on said AlGaAs layer at opposite sides of said ridge; a first semiconductor layer epitaxially disposed on said low temperature buffer layer at opposite sides of said ridge; and a second semiconductor layer epitaxially disposed on said ridge and said first semiconductor layer.

Abstract: A semiconductor laser device element substrate includes a plurality of semiconductor laser device elements arranged in an array on a semiconductor substrate, the array including a plurality of rows and a plurality of columns, laser resonator facets being located at the boundaries between respective rows of the semiconductor laser device elements, and element separation guiding grooves, for guiding separation of the substrate into a plurality of divided semiconductor laser devices, the grooves being located at the boundaries between the semiconductor laser device elements of the respective columns, wherein the element separation guiding grooves are arranged at positions on different straight lines running in the column direction for each group at least two adjacent rows. Therefore, even if some forces are applied to the substrate, the forces are not concentrated on a point, whereby wafer cracking can be prevented.

Abstract: A semiconductor laser includes a first conductivity type semiconductor substrate; a double-heterojunction structure including a first conductivity type cladding layer, an active layer, and a second conductivity type cladding layer successively disposed on the semiconductor substrate; two parallel stripe grooves forming the double-heterojunction structure in a mesa shape; a first conductivity type mesa embedding layer, a second conductivity type current blocking layer, and a first conductivity type current blocking layer successively disposed on the semiconductor substrate and contacting opposite sides of the mesa; and impurity doped regions formed by adding an impurity through the surface of the first conductivity type current blocking layer. The impurity doped regions electrically separate an upper part of the mesa from the second conductivity type current blocking layer at opposite sides of the mesa.

Abstract: In a method for producing a semiconductor device, a first semiconductor layer is epitaxially grown on a semiconductor substrate, an insulating film pattern is formed on the first semiconductor layer, and portions of the first semiconductor layer are removed by wet etching using the insulating film pattern as a mask to leave a ridge having a reverse mesa shape and a width. Ends of the insulating film pattern are removed by etching to approximately the width of the ridge, a second semiconductor layer is epitaxially grown on opposite sides of the ridge, and a third semiconductor layer is epitaxially grown on the ridge and the second semiconductor layer. The second semiconductor layer is evenly grown without concave portions at opposite sides of the ridge. In addition, the third semiconductor layer is evenly grown on the ridge and the second semiconductor layer, and an electrode reliably connects the surface of the third semiconductor layer.

Abstract: A band-pass filter which includes a plurality of dielectric coaxial resonators which are arranged in a parallel relation and extending axially in the same direction, and have respective coupling terminals inserted therein, and a dielectric substrate formed, on its first surface, with a plurality of coupling electrodes for connecting the respective coupling terminals. The coupling electrodes on the first surface of the dielectric substrate have an inductance element between them for connecting at least two coupling electrodes to each other. Confronting electrodes facing the coupling electrodes are formed on the other surface of the dielectric substrate to from a capacitance bypass circuit. The inductance element may be a printed circuit on the dielectric substrate or an air-core coil. The air-core coil may be located either adjacent the first surface of the substrate, or away from the substrate between the resonators.