Abstract:
A phase modulator for a microwave band having a desirable modulation characteristic by maintaining the impedance thereof constant, includes two PIN diodes 2 and 3 connected to a merchant balun 1 and a bias circuit 18 which supplies bias voltages to the PIN diodes 2 and 3 such that the sum of the bias voltages applied to the diodes 2 and 3 is constant. The bias voltages are selected so as to have the input and output impedances to be in the most stable state when a modulation signal is equal to zero.
Abstract:
A method for producing a semiconductor laser device includes the steps of: forming window layers on either one of a top surface of an internal structure or a reverse surface of a substrate and on light-emitting end facets of the internal structure; forming a reflection film on the light-emitting end facets; removing the window layer formed on either one of the top surface or the reverse surface by using an etchant which hardly etches the reflection film; and forming electrodes on the surface from which the window layer is removed by etching and on the other surface. Another method for producing a semiconductor laser device includes the steps of: forming window layers on light-emitting end facets of the bars; inserting the bars into an apparatus having openings for forming electrodes and a supporting portion for preventing a positional shift between the bars and the openings, and forming the electrodes on the top surfaces and the reverse surfaces of the bars; and cutting the bars into the chips.
Abstract:
A radio transmitter suitable for a frequency hopping communication system which transmits a phase modulated signal with a minimum of spurious signals and phase noise. A direct digital frequency synthesizer (DDS) generates a frequency hopping signal lying in the VHF band. A first phase locked oscillator reduces the spurious components of the frequency hopping signal to produce a corresponding signal lying in the UHF band. This UHF band signal is used as a reference signal for a second phase locked oscillator which sends the phase modulated signal via a voltage controlled oscillator (VCO) built therein. The second phase locked oscillator includes a modulator for further modulating the phase of the phase modulated signal or a frequency divided version thereof by a modulating signal. The output of the modulator is used as a signal to be compared by a phase comparator or a source of signal to be compared. Since the second phase locked oscillator has a phase locked loop band sufficiently broader than the signal band of the modulating signal, it not only generates the phase modulated signal capable of sufficiently following the modulating signal, but also suppresses phase noise of the phase modulated signal ascribable to the VCO.
Abstract:
A surface electrode on a surface of a LED has a pad, and further, at least first-order branches linearly extending from the pad, second-order branches diverged and linearly extending from the first-order branches, and third-order branches diverged and linearly extending from the second-order branches. The pad out of the surface electrode is not in electrical contact with a underlying semiconductor layer, whereas the surface electrode and the semiconductor layer are in electrical contact with each other at ends of the highest-order branches. Also, the semiconductor layer is provided along a pattern of the surface electrode in a mesa shape. Thus, ineffective light emission underneath the surface electrode is relatively reduced so that external quantum efficiency can be improved, and moreover even shorter-wavelength light can be allowed to go out at high efficiency by omitting a current diffusion layer.
Abstract:
Drive wheel slip control system for a vehicle includes means for setting a reference value for slippage of a drive wheel providing an appropriate slip condition, means for reducing the drive wheel torque when the slippage exceeds the reference value, means for detecting the opening degree of an accelerator of a prime mover which drives the drive wheel, and means for correcting the reference value dependent on signals from the detecting means. The vehicle responds to accelerator operation even during control of the drive wheel slip, enabling a sporty travel.
Abstract:
There is provided a method for the production of a semiconductor laser device which emits laser light from an end facet thereof. This method comprises the steps of: forming a multi-layered structure including an active layer for laser oscillation on a semiconductor substrate; etching the semiconductor substrate and the multi-layered structure to form a pluralilty of striped grooves parallel to each other in such a manner that a plurality of projections are formed on the side face of the multi-layered structure in the striped grooves; separating the projections from the multi-layered structure to form a pair of cleavage planes each functioning as a resonator facet; forming a large-band-gap layer on at least one of the cleavage planes on the light-emitting side, the large-band-gap layer having a larger band gap than that of the active layer; forming a reflecting film on the large-band-gap layer; and finally cleaving the semiconductor substrate and the multi-layered structure to obtain a plurality of semiconductor laser devices.
Abstract:
A light wavelength converter which includes a light source for emitting fundamental waves having a desired wavelength, a first loop-shaped optical waveguide for converting the fundemental waves into harmonics, and a second optical waveguide for receiving the light from the source, wherein the two waveguides are coupled by an optical directional coupler.
Abstract:
A light wavelength converter comprising a substrate that is made of a material with a non-linear optical effect, and a loop-shaped optical waveguide that is formed on the substrate, whereby a second harmonic wave or a sum wave emanates from a fundamental wave that has been propagated in a specific area of the optical waveguide and part of the fundamental wave that has not been converted to the second harmonic wave or the sum wave is returned to the specific area of the optical waveguide, so that a fundamental wave with a relatively low output can be efficiently converted to a second harmonic wave and a high-output second harmonic wave can be obtained.
Abstract:
A steering wheel turning angle detector for a vehicle, includes a steering wheel turning angle sensor attached to a steering wheel for detecting a steering wheel turning angle, a yaw rate detector for detecting a yaw rate of the vehicle, a steering wheel turning angle prediction circuit, receiving an output from the yaw rate detecting means for predicting the steering wheel turning angle in response to the detected yaw rate, and a steering wheel turning angle correcting circuit, receiving output signals from the steering wheel turning angle sensor and the steering wheel angle prediction circuit, for correcting an output value of the steering wheel turning angle sensor in response to an error between outputs from the steering wheel turning angle sensor and the steering wheel turning angle prediction circuit.
Abstract:
An external resonator type semiconductor laser apparatus comprising a semiconductor laser device, a reflector positioned behind said laser device in a manner to face the light-emitting rear facet of said laser device, and a photodetector, for detecting the optical output of said laser device, positioned backward of said reflector, wherein a part of the laser light from said light-emitting rear facet is reflected by said reflector and the reflected light is then incident to said photodetector.