Abstract: A first dielectric wall and a second dielectric wall in which hollow alumina cylindrical columns are arranged in layers so that axial centers of the alumina cylindrical columns describe planar triangular lattice arrays, are opposed to each other, and are parallel to air interposed between them. Metal plates are opposed to each other and have end faces of the alumina cylindrical columns interposed between and connected to the metal plates. The first and second dielectric walls and the metal plates are bonded to one another, as a high-frequency waveguide with reduced radiation loss, and that is inexpensive and low in transmission loss.

Abstract: A first dielectric wall and a second dielectric wall in which hollow alumina cylindrical columns are arranged in a layered form so that the axial centers of the alumina cylindrical columns have planar triangular lattice arrays, are opposed to each other in parallel with air interposed therebetween. Metal plates are opposed to each other with both end faces of the alumina cylindrical columns constituting the first dielectric wall and the second dielectric wall being interposed therebetween. Further, the first and second dielectric walls and and the metal plates are bonded to one another, whereby a high-frequency waveguide is configured which is reduced in radiation loss, inexpensive and low in transmission loss.

Abstract: A semiconductor laser includes a semiconductor substrate of a first conductivity type, a gain guiding structure comprising of a first conductivity type, a lower cladding layer disposed on the substrate, an active layer disposed on the lower cladding layer and having a light emitting region, and an upper cladding layer of a second conductivity type, opposite the first conductivity type, disposed on the active layer, and a multiquantum barrier layer interposed between the upper cladding layer and the active layer excluding the light emitting region. In this structure, the multiquantum barrier layer reduces leakage current flowing outside of the light emitting region of the active layer and increases effective current flowing into the light emitting region, whereby the light output of the laser is significantly increased.

Abstract: In a semiconductor pulsation laser, an active layer includes a double quantum well structure including two quantum wells. Each of these quantum wells has a plurality of discrete energy levels in which the difference in energies between these energy levels is more than 10 nm when calculated as a wavelength equivalent. These two quantum wells are arranged close each other in the double quantum well structure so that each of the discrete energy levels is divided into two energy levels so that the difference in energies between these two energy levels is equivalent to a difference in energies that provides a frequency at which both electrons and holes are alternatingly present in the two quantum wells in a range from 100 MHz to 10 GHz. The gain at which laser oscillation occurs by recombination of electrons and holes is attained only when both electrons and holes are present in the same well at the same time.

Abstract: A semiconductor laser device having an active region with a wide and uniform width which supports propagation of fundamental and higher modes of oscillation includes a reflecting film coating having a reflectivity smaller than a reflectivity determined by the differences between the refractive index of the semiconductor that forms the active layer and air and having no spatial distribution of reflectivity in the direction of the width of the active region disposed on an emitting facet of the laser, and a reflecting film coating having a highest reflectivity at the center of the width of the active region, the reflectivity decreasing at the sides of the center, disposed on the facet opposite to the emitting facet. As a result, a semiconductor laser oscillating in the fundamental mode with high power light output is provided.

Abstract: A semiconductor laser apparatus in accordance with the present invention comprise: a semiconductor laser chip including a resonator with a couple of opposite end faces of which one is provided with an antireflective coating and the other with a highly reflective coating; a stem having a main surface to which the chip is attached with the end faces being vertical to the main surface; and a photoelectric conversion device, a major surface of which absorbs a part of a laser beam emitted from said one end face thereby to monitor intensity of the beam and reflects the remaining part of the beam for practical use.

Abstract: A semiconductor laser device is fabricated by forming a first semiconductor layer of N type GaAs to be a current narrowing layer on a P type GaAs semiconductor substrate, forming a second semiconductor layer of P type AlGaAs on the first semiconductor layer, removing said second semiconductor layer by etching except the proximity of the portion to be the end surface of a resonator, forming a striped groove which is deep enough to penetrate the first semiconductor layer and extends to that direction which crosses the surface to be the end surface of the resonator and, depositing a lower clad layer, an active layer, an upper layer and a contact layer in this order.

Abstract: A surface-emitting injection type laser device has a semiconductor wafer including a first and a second main face opposite to each other and an active layer located on the side of the first main face. A single mode optical fiber chip has a first and second end surface perpendicular to its optical axis and is disposed on the semiconductor wafer with the first end surface contacting the second main face through a reflection preventing film. A dielectric film is disposed on the second end surface of the optical fiber chip to increase the reflection power at the second end surface and forming a resonator with the first main face of the semiconductor wafer.