Abstract: It is a problem of disclosed technology to provide a polymer optical waveguide substrate having a V-groove for fiber alignment providing optical coupling with an optical fiber with low loss.

Abstract: A polymeric optical waveguide substrate comprises a first region provided thereon with a polymer optical waveguide and an optical waveguide-free second region, the first and second regions being present on the same substrate, wherein it comprises an adhesive layer between the lowermost polymer layer constituting the optical waveguide in the first region and the substrate, for improving the adhesion or adhesive properties of them and wherein it has a groove intruding into the substrate at the boundary between the first and second regions.

Abstract: An LD module capable of generating a good optical waveform at a high speed of about 10 Gbit/s or higher in which a damping resistor is disposed in parallel with a laser-diode device in the inside of a laser-diode module, the damping resistor being preferably disposed between the connection point of the high-frequency transmission line and the terminating resistor, and the ground.

Abstract: The invention provides an optical element comprising a substrate having provided thereon a coating of an organic zirconium compound, a coating of a fluorine-free polyimide resin and a coating of a fluorine-containing polyimide resin, in this order. The element has increased adhesive property with the substrate and reliability.

Abstract: The subject to be attained by the disclosed technique is to provide an optical unit less expensive than conventional like optical units and having a wavelength multiplexer and optical waveguides.

Abstract: An object of the disclosed technology is to realize, at low cost, an optical communication module capable of high-speed operation and having an excellent EMC property.

Abstract: The subject to be attained by the disclosed technique is to provide an optical unit less expensive than conventional like optical units and having a wavelength multiplexer and optical waveguides. For achieving the above subject there is provided a wavelength multiplexer wherein a light combining/branching section is constituted by a multi-mode interference type optical waveguide, and an incident-side optical waveguide and a reflection-side optical waveguide are spaced a predetermined distance from each other at their connections to the multi-mode interference type optical waveguide. An optical filter is installed in the multi-mode interference type optical waveguide and a multi-mode interference is set so that a peak in a light intensity distribution is formed in the vicinity of an inlet of each of an exit-side optical waveguide and the reflection-side optical waveguide.

Abstract: It is a problem of disclosed technology to provide a polymer optical waveguide substrate having a V-groove for fiber alignment providing optical coupling with an optical fiber with low loss.

Abstract: An object of disclosed technology is to control lasing wavelengths so that a wavelength shift does not occurs. Another object is to permit wavelengths of a light source for wavelength division multiplexing optical-fiber communication system to be variable in response to an ITU-TS grid. A means for achieving the objects is as follows: locating an etalon in a light path of diode laser light, which is a parallel plane wave changed by a collimator lens; generating a wavelength error signal from a difference between both of divided pieces of light from transmitted light or reflected light; and locking a wavelength of a diode laser device according to the wavelength error signal.

Abstract: A method is supported for aligning the height of a polymer waveguide to the height of a core layer of a semiconductor element in an optical module composed so as to mount the semiconductor element on its polymer waveguide substrate. In order to achieve the method, at first a waveguide is formed on the silicon substrate coated with an oxide film using a polymer whose refractive index is larger than that of the oxide film. The waveguide consists of a lower cladding layer, a core layer, and an upper cladding layer. The lower cladding layer is formed to be thinner than the conventional one and the height of the core layer is set to 5 to 10 &mgr;m. In this way, it is possible to fabricate an optical module in less process steps and at a lower cost than the conventional one.

Abstract: The subject to be attained by the disclosed technique is to provide an optical unit less expensive than conventional like optical units and having a wavelength multiplexer and optical waveguides.

Abstract: The present application provides an asymmetric Y branch optical waveguide capable of obtaining an asymmetric branching ratio stably with a low radiation loss, and a lightwave circuit and an optical transmission system both using the asymmetric Y branch optical waveguide. The asymmetric Y branch optical waveguide according to the present application has a waveguide (I) for input, two waveguides (III) for output, and a multi-mode waveguide (II) disposed between the waveguides (I) and (II). The present Y branch optical waveguide is constructed in such a manner that the width of the multi-mode waveguide, extending in the direction intersecting with an optical axis changes discontinuously at a portion where the input waveguide and the multi-mode waveguide are connected to each other, and the multi-mode waveguide is asymmetric with respect to a center line extending in the direction of the optical axis to allow optical peaks to respectively appear in each individuals of the two output waveguides.

Abstract: The following are disclosed: An optical wave-guide constituted out of polymers, an optical integrated circuit, an optical module, and an optical communication system (optical communication apparatus) using these. In the polymer optical waveguide which is fabricated on a substrate having an inorganic material on at least a part of the surface thereof and in which a core layer and a clad layer positioned closer to the base than the core layer are composed of polymers, a buffer layer, which is composed of a polymer different from that of the clad layer, is provided between the clad layer and the base.

Abstract: A semiconductor optical device, a fiber optical amplifier and an optical transmission system are disclosed. The semiconductor optical device is excellent in the stability of the coupling efficiency and the splitting ratio of a Y-branch. Both the fiber optical amplifier and the optical transmission system operate in a stable manner over a long period of time even if an optical waveguide is employed which is operative in a multi-mode in the transverse direction. The semiconductor optical device has an optical waveguide, a mode filter for transmitting therethrough light of a fundamental mode and blocking the propagation of light of a higher-order mode. The mode filter is provided in at least a part of the optical waveguide. The width of the mode filter is larger than that of the optical waveguide.

Abstract: In the structure of the device of the invention, a supper-lattice buffer layer is formed between the undoped layer and doped layers. This super-lattice buffer layer serves as a carrier-piling up layer in place of the undoped layer in the conventional device. Thus, the amounts of the piled-up carriers in the undoped layer can be greatly reduced and hence no band filling effect occurs in the undoped layer. Consequently, an optical device having a flat frequency characteristic can be produced without losing its modulating characteristic.

Abstract: A passive region is provided on one side or both sides of a waveguide-type optical modulator. Thereby, it is possible to obtain a high-speed optical modulator package superior in mechanical strength, thermal characteristic, high-frequency characteristic, and extinction characteristic. Moreover, it is possible to increase the operating speed of an optical fiber transmission equipment by applying the optical modulator package to the optical fiber transmission equipment.

Abstract: An integrated optical semiconductor device and an optical fiber gyroscope using the same. The semiconductor device comprises a super luminescence diode, at least one waveguide type photo-diode and at least one Y-branch integrated on a single semiconductor substrate. The waveguide structure of the super luminescence diode, photo-diode and Y-branch shares common optical guide layers formed by concurrent crystal growth. At least part of the optical guide layers are located on the side of the semiconductor substrate away from an active layer of the super luminescence diode and an optical absorption layer of the photo-diode.

Abstract: A waveguide device includes an indium phosphide substrate, an active layer formed on the indium phosphide substrate, and a cladding layer formed on the active layer, the cladding layer having a ridge structure the side wall of which is configured into a reversed mesa form.

Abstract: Disclosed is a semiconductor optical integrated device and method of fabricating the device, the device having a plurality of quantum well structures, formed on a single substrate, acting as optical waveguides, the plurality of quantum well structures respectively having different lattice mismatches with the substrate and/or different strains (e.g., respectively compressive strain and tensile strain). The method includes selectively depositing the quantum well structures by, e.g., organometallic vapor phase epitaxy on growth regions of the substrate, the growth regions being defined by insulating layer patterning masks, with a width of the growth regions and/or a width of the patterning mask being different for the different quantum well structures.

Abstract: A waveguide device includes an indium phosphide substrate, an active layer formed on the indium phosphide substrate, and a cladding layer formed on the active layer, the cladding layer having a ridge structure the side wall of which is configured into a reversed mesa form.