Abstract: An optical demultiplexer comprises a clock regenerating circuit for regenerating a clock signal for each optical signal channel from an optical multiplexed signal. An optical switch separates each optical signal channel from the optical multiplexed signal in accordance with the clock signal regenerated by the clock regenerating circuit. An identification information extraction circuit extracts identification information contained in each optical signal channel separated by the optical switch. A control circuit changes output destinations so that each optical signal channel is output to a designated destination in accordance with the identification information extracted by the identification information extraction circuit. The identification information is appended as identification data to a data signal represented by the optical signal, and the identification information extraction circuit extracts the identification data contained in the data signal reconstructed from each optical signal channel.

Abstract: The invention provides a technique for optimizing transmission conditions to achieve large-capacity transmission, and also provides peripheral techniques for the practical implementation of optical multiplexing that makes large-capacity transmission possible. A transmission characteristic is measured in a transmission characteristic measuring section, and control of signal light wavelength in a tunable light source, control of the amount of prechirping, control of the amount of dispersion compensation, and/or control of optical power are performed to achieve the best transmission characteristic. Wavelength dispersion is deliberately introduced by a dispersion compensator, to reduce nonlinear effects. A tunable laser is used to optimize signal light wavelength for each optical amplification repeater section. Peripheral techniques, such as drift compensation, clock extraction, optical signal channel identification, clock phase stabilization, etc., are provided for the implementation of optical multiplexing.

Abstract: The invention provides a technique for optimizing transmission conditions to achieve large-capacity transmission, and also provides peripheral techniques for the practical implementation of optical multiplexing that makes large-capacity transmission possible. A transmission characteristic is measured in a transmission characteristic measuring section, and control of signal light wavelength in a tunable light source, control of the amount of prechirping, control of the amount of dispersion compensation, and/or control of optical power are performed to achieve the best transmission characteristic. Wavelength dispersion is deliberately introduced by a dispersion compensator, to reduce nonlinear effects. A tunable laser is used to optimize signal light wavelength for each optical amplification repeater section. Peripheral techniques, such as drift compensation, clock extraction, optical signal channel identification, clock phase stabilization, etc., are provided for the implementation of optical multiplexing.

Abstract: A waveguide-type optical device includes a substrate with an electro-optical effect, two adjacent optical waveguides, a signal electrode covering either of the optical waveguides and an earth electrode covering the other optical waveguide and having a segment of the same form as the signal electrode which lies close to the other optical waveguide.

Abstract: Disclosed is an optical control device which has a LiNbO3 or LiTaO3 crystalline substrate having electrooptic effect; a channel-type optical waveguide which is formed in the crystalline substrate by doping metal; an optically transparent film layer formed on the crystalline substrate; and electrodes formed on the optically transparent film layer; wherein the crystalline substrate has a surface except a region which waveguided-light through the channel-type optical waveguide propagates or an entire surface under which a layer doped by metal is formed.

Abstract: Disclosed is an optical control device which has a substrate with a pyroelectric effect; optical waveguides formed on the surface of the substrate; a pair of electrodes formed near the optical waveguides; a film layer formed between the substrate and the electrodes; and conductive film which covers near the electrodes and has a conductivity higher than that of the film layer; wherein the conductive film has a plurality of insulating portions between the electrodes.

Abstract: An optical control device has two waveguides close to each other formed in a main surface of a substrate of a dielectric and light-transparent material with an electrooptic effect, three electrodes formed on the main surface at an inside area and opposite outside areas of the waveguides, respectively, and a so-called buffer layer interposed between the main surface and the electrodes. In order to suppress the so-called DC drift and to reduce the driving voltage, the buffer layer is separated into three sections under the three electrodes and are spatially separated from one another. Each of two outside electrodes is partially in direct contact with the main surface by extending along a side surface of each of the outside buffer layer sections. Alternatively, the outside electrode is partially in direct contact with the main surface through a hole formed in the outside buffer layer sections.

Abstract: In an optical coupling device for optically coupling an optical fiber to an optical waveguide formed on a crystalline substrate, the optical fiber is placed in a V-shaped groove formed on the substrate by anisotropic etching. The V-shaped groove is not linearly continuous, but intermittent to intermittently support the optical fiber. The intermittence of the V-shaped groove decreases undesired width expansion of the V-shaped groove. For this structure, a light axis alignment between the optical fiber and the optical waveguide is enhanced.

Abstract: A cladding layer covers a part of a substrate and two core layers are formed in the cladding layer. The two core layers merge with each other and a head of a common part of the two core layers appears on a side wall of the cladding layer. A guide portion is located near the side wall. A reflective body having an end face coated with a reflective film is positioned by the guide portion so that the head of a common part of the two core layers adheres to the reflective film.

Abstract: An etching pattern for forming a groove to be mounted by an optical fiber, marks for positioning an optical semiconductor laser, a semiconductor photodetector, and an optical multiplexing and demultiplexing device, marks for aligning device, marks for aligning optical waveguides to the laser, the photodetector, and the multiplexing an demultiplexing device, and electric interconnections and pads for an electronic semiconductor device and the above described optical parts are defined on a semiconductor substrate prior to the formation of the optical waveguides.

Abstract: This invention provides a cationic electrodepositable coating composition comprising:(A) 30 to 1% by weight of a high-molecular-weight polyurethane resin prepared by reacting (a) an organic polyisocyanate, (b) a high-molecular-weight polyol, and (c) a diol having at least one tertiary amino group, the high-molecular-weight polyurethane resin (A) having a SP value of 9.5 to 12.0 and a number average molecular weight of at least 15,000; and(B) 70 to 99% by weight of an epoxy-type cationic electrodepositable resin.

Abstract: In a waveguide-type optical device, two optical waveguides are formed in a substrate of LiNbO.sub.3 or LiTaO.sub.3. On the substrate and the two waveguides, a blocking layer is formed to block a diffusion of Li ions from the substrate. On the blocking layer, a buffer layer made from SiO.sub.2 is formed. Each of the electrodes, from which operation voltages are supplied, covers each coupling part of the two optical waveguides, respectively, via the blocking layer and the buffer layer.

Abstract: An optical waveguide having a small propagation loss and formed on an Si substrate having a large diameter has a lower cladding layer, a core and an upper cladding layer surrounding the core together with the lower cladding layer, each of the lower cladding layer, core and upper cladding layer being composed of a high-silica material. The upper cladding layer or each of the upper and lower cladding layers comprises three kind of dopants including germanium oxide (GeO.sub.2), phosphorus oxide (P.sub.2 O.sub.5) and boron oxide (B.sub.2 O.sub.3). Preferable amount of content of GeO.sub.2 in the upper cladding layer is more than 5 mole percent. The optical waveguide is suitable for a hybrid optical device including a functional device such as a semiconductor laser provided with metal patterns for electrodes and interconnections. The metal pattern can be formed before a thermal treatment of the upper cladding layer without causing a deficiency in the metal pattern during the thermal treatment.

Abstract: A supervisory and control signal transmitting system for use in an optically amplifying repeater system amplifies attenuated light and for transmitting data over a long distance between a transmitting station and a receiving station through a plurality of repeaters.

Abstract: Resin compositions of improved dispersibility and mechanical properties are obtained by polymerizing a polymerizable compound (A), insitu in a melted thermoplastic resin (B), in the presence of a dispersant (C) reactive or compatible with at least one of the resin (B) and polymerizate of (A).Suitable dispersants include those represented by the general formula (1) or (2)R.sub.1 --L(X--M--X--L).sub.n X--M--R.sub.2 (1)R.sub.1 --L(X--M--X--L).sub.n --R.sub.2 (2)wherein R.sub.1 and R.sub.2 are groups, such as hydrocarbyl acyl, alkoxy, hydroxyl, mercapto, amino, epoxy, isocyanate, carboxylic, carboxylic anhydride, carboxylic halide and aldehyde groups; L and M are residues of a polymer having a number average molecular weight of about 500-about 3,000,000, the difference in solubility parameter between the residue L or M and the resin (B) or polymerizate of (A) being not more than 0.

Abstract: An optical transmitter having a Mach-Zehnder optical modulator comprising a signal electrode fed with a driving signal for effecting modulation and a bias electrode for operating point control. Because the signal electrode and the bias electrode are independent of each other, a driving circuit and the signal electrode can be connected in a DC setup. This permits stable operating point control and improves waveform characteristics.

Abstract: An optical transmitter operates on the DPSH-IM (direct phase-shift and self-homodyne intensity modulation) principle. The optical transmitter slightly amplitude-modulates the modulation current of a laser diode using a low frequency signal and detects the modulated component from the optical output. These features stabilize the operating point and improve the transmission waveform.

Abstract: An optical control device such as an optical switch includes two waveguides formed in an electrooptical substrate. Two control electrodes are preferably formed respectively above the two waveguides through a buffer layer. The optical control device is further provided with additional electrodes formed where there is no waveguide therebelow. The additional electrodes are connected with either of the two control electrodes, so that there generates an electric field not only in the direction vertical to the surface of the substrate but in the direction parallel to the surface thereof.

Abstract: An optical, transmitter with a stabilized operating point for an optical transmitter, especially for that including a Mach-Zehnder optical modulator, is disclosed. An optical modulator is provided which modulates a light beam from a light source according to a driving voltage from a drive circuit. An operating point stabilizing circuit is provided which detects a drift in the characteristic curve from the optical modulator and controls the optical modulator to bring the operating point to a specified position. Deterioration in the waveform of the output optical signal due to the operating point drift is thereby prevented without depending on the input signal. Further, by performing an operating point shift under specific conditions, deterioration in the waveform due to wavelength dispersion can be effectively prevented, whether the sign of the wavelength dispersion is positive or negative.

Abstract: An optical waveguide circuit comprises intersections each including two optical waveguides which intersect with each other by a predetermined intersecting angle. The intersection includes an island region and a peripheral region surrounding the island region. The peripheral region has a refractive index which is lower than that of optical waveguides, so that an intersecting loss is lowered.