Abstract: A program transmitting/receiving system has a center device and a terminal device connected through a communication device to the center device. The center device has a program information memory, a program information transmitter, a broadcasting device, and a request program transmitter. The terminal device has a program information receiver, a program receiver, an image information generator, a program request signal transmitter, and a request program receiver. The memory stores a program information. The program information transmitter transmits the program information to the terminal device. The broadcasting device broadcasts the program to the terminal device in accordance with a schedule, and stores the program. The request program transmitter receives a request signal of the program from the terminal device, and transmits the program corresponding to the request signal to the terminal device. Then, the program information receiver receives the program information.

Abstract: Terminal equipment has a master terminal (1) and a slave terminal (2), the master terminal (1) includes a first tuner (TA) receiving the cablecast signal for television programming delivered from the cable television station, and applying an image signal produced from the cablecast signal to a first television receiver (3); a second tuner (TB) receiving a cablecast signal, and applying an image signal produced from the cablecast signal; and a transmitter/receiver (RT) radio-transmitting the image signal output from the second tuner section, the slave terminal (2) includes a radio-receiving section for receiving the image signal transmitted from the transmitter/receiver (RT) of the master terminal (1), and applying the image signal, received by the radio-receiving section, to a second television receiver (5).

Abstract: A CATV station 1 for broadcasting a television program is connected to an internet network B. The CATV station 1 is connected to a terminal device 2. The terminal device includes a tuner section T for receiving a broadcasting signal for the television program transmitted from the CATV station, an interface section S for making transmission/reception of a telephone signal for the internet network B and a switching circuit 5 which is connected to the interface section, a telephone set 3 and a public switched phone network C. The switching circuit 5 selectively connects the telephone set 3 to the interface section S or the public switched phone network. In this configuration, the internet telephone can be used without doing troublesome operations, and the public switched phone network or internet network can be selected according to the facility of the internet terminal device on the side of a called party so that telephone call can be executed easily.

Abstract: An object of the present invention is to provide a semiconductor laser device which is capable of selectively emitting two kinds of laser light of light emitting characteristics differing in wavelength, light emission point, beam shape, light emission power, longitudinal mode and so on, by switching the direction of the voltage applied to the device. There is provided the semiconductor laser device including first and second laser units, each unit having a ridge type structure and each unit comprising a multilayer structure body made of at least an n-type semiconductor layer, an active layer and a p-type semiconductor layer deposited in this order, and a p-side electrode and an n-side electrode, wherein the p-side electrode and the n-side electrode of the first laser unit and the n-side electrode and the p-side electrode of the second laser unit are electrically connected, respectively.

Abstract: A nitride semiconductor light emitting device having preferable light emitting characteristics even if dense threading dislocations extend through single crystal layers. The nitride semiconductor light emitting device includes an active layer obtained by depositing group-3 nitride semiconductors, and a barrier layer disposed adjacent to the active layer and having a greater bandgap than that of the active layer, the active layer having barrier portions which surround the threading dislocations and are defined by interfaces enclosing the threading dislocation and which are made of the same material as that of the barrier layer.

Abstract: A GaN based semiconductor laser device which can prevent guided mode light emitted from the active layer from leaking through the cladding layer to the underlying layer without making the cladding layer excessively thick is provided. The device is characterized in that if an n-type cladding layer, a waveguide layer and a p-type cladding layer are collectively defined as a first three-layer waveguide path and a substrate, an underlying layer and an n-type cladding layer are collectively defined as a second three-layer waveguide path, then effective refractive indices of light propagating through the first and second three-layer waveguide paths are set different from each other.

Abstract: A semiconductor laser having the characteristic of a stable lateral transverse mode and the fabricating method therefor. The method for fabricating a GaN-based semiconductor laser is characterized by comprising the steps of forming a first mask on a first conductive layer composed of an n-type semiconductor, depositing a second conductive layer of a thickness not exceeding the thickness of the first mask, removing the first mask, depositing an n-type cladding layer, depositing optical waveguide layers including at least an active layer, and depositing a p-type cladding layer.

Abstract: A nitride semiconductor light emitting device having preferable light emitting characteristics even if a threading dislocation extends through single crystal layers.

Abstract: A nitride semiconductor light emitting device having preferable light emitting characteristics even if dense threading dislocations extend through single crystal layers. The nitride semiconductor light emitting device includes an active layer obtained by depositing group-3 nitride semiconductors, and a barrier layer disposed adjacent to the active layer and having a greater bandgap than that of the active layer, the active layer having barrier portions which surround the threading dislocations and are defined by interfaces enclosing the threading dislocation and which are made of the same material as that of the barrier layer.

Abstract: In the tracking control unit of an optical information reading apparatus to perform "Heterodyne Method", electric signals from the respective quadrant-separated subdetectors are inputted to a first adder to obtain a reference sum total signal whose phase is 0.degree.. Regarding phase difference, the sum total signal is compared with a first electric signal from an arbitrary one of the quadrant-separated subdetectors and a second electric signal from the other of the subdetectors located in the diagonal relationship with respect to the arbitrary subdetector, respectively, to produce a first and a second phase compared result signals which are added to each other by a second adder whereby a precise tracking control can be attained irrespective of the existence of any scratch or stain.