Abstract: A pulsed doppler radar system having an improved detection probability, comprising an antenna unit, a transmitter for transmitting a signal through the antenna unit, a receiver for receiving a signal reflected by a target through the antenna unit to provide a reception signal. A processing unit which receives the reception signal from the receiver determines, in accordance with a range of the target and a signal-to-noise ratio and bandwidth of the reception signal, an optimum integration number which maximizes the detection probability and performs coherent integration on the reception signal by the number of times equal to the determined optimum integration number thereby outputting a signal having a predetermined level. Such a signal is fed to a display and an image of the target is displayed on a display.

Abstract: A double heterojunction semiconductor laser according to the invention includes first and third cladding layers sandwiching an active layer. The third cladding layer includes a mesa opposite a light emitting region of the active layer. The mesa is confined by a current blocking layer. A cap layer that is part of the mesa is used as a dopant diffusion source to dope a light emitting region of the active layer heavily. A second cladding layer may be present between the active layer and third cladding layer having the same conductivity type as the third cladding layer adjacent the light emitting region but the opposite conductivity type elsewhere. A semiconductor laser according to the invention may also include a stripe groove structure.

Abstract: A semiconductor laser includes, serially disposed, a semiconductor substrate of a first conductivity type, a semiconductor current blocking layer of a second conductivity type opposite the first conductivity tyupe, a first semiconductor cladding layer of the first conductivity type, an active semiconductor layer, a second semiconductor cladding layer of the second conductivity type, and a semiconductor contacting layer of the second conductivity type, and a structure for laterally confining the transverse flow of electrical current through the layers, the structure including a portion of the first cladding layer being disposed in a longitudinal groove extending through the current blocking layer into the substrate and high resistance longitudinal stripes disposed adjacent the groove between the second cladding layer and the current blocking layer, the high resistance stripes forming discontinuities in the active semiconductor layer.

Abstract: A semiconductor laser includes, serially disposed, a semiconductor substrate of a first conductivity type, a semiconductor current blocking layer of a second conductivity type opposite the first conductivity type, a first semiconductor cladding layer of the first conductivity type, an active semiconductor layer, a second semiconductor cladding layer of the second conductivity type, and a semiconductor contacting layer of the second conductivity type, and a structure for laterally confining the transverse flow of electrical current through the layers, the structure including a portion of the first cladding layer being disposed in a longitudinal groove extending through the current blocking layer into the substrate and high resistance longitudinal stripes disposed adjacent the groove between the second cladding layer and the current blocking layer, the high resistance stripes forming discontinuities in the active semiconductor layer.

Abstract: A high-power AlGaAs/GaAs laser device comprises: a ridge formed on the top surface of a substrate from one end to the opposite end, thereof wherein the width of the ridge is made narrower in regions near both the ends and wider in a middle region; a depression is formed in the wider region of the ridge; a clad layer is grown epitaxially over the top surface of the substrate; and an active layer is grown epitaxially on the clad layer, wherein the thickness of the active layer is thinner in portions just above the narrower ridge regions and relatively thicker in a portion just above the wider ridge region.

Abstract: A high-power AlGaAs/GaAs laser device comprises: a ridge formed on the top surface of a substrate from one end thereof to the opposite end, wherein the width of the ridge is made narrower in regions near both the ends and wider in a middle region; a depression is formed in the wider region of the ridge; a clad layer is grown epitaxially over the top surface of the substrate; and an active layer is grown epitaxially on the clad layer, wherein the thickness of the active layer is thinner in portions just above the narrower ridge regions and relatively thicker in a portion just above the wider ridge region.