Abstract: The object is to provide a polyimide ink composition having good printing properties and good continuous priming properties, which composition can be dried at a low temperature of not higher than 220° C., and which composition gives a coating film, after being dried, having excellent dimensional stability, heat resistance, low modulus of elasticity, flexibility, resistance to warping, chemical resistance, adhesiveness with substrates, and plating resistance.

Abstract: The object is to provide a polyimide ink composition having good printing properties and good continuous printing properties, which composition can be dried at a low temperature of not higher than 220° C., and which composition gives a coating film, after being dried, having excellent dimensional stability, heat resistance, low modulus of elasticity, flexibility, resistance to warping, chemical resistance, adhesiveness with substrates, and plating resistance.

Abstract: The object is to provide a polyimide ink composition having good printing properties and good continuous printing properties, which composition can be dried at a low temperature of not higher than 220° C., and which composition gives a coating film, after being dried, having excellent dimensional stability, heat resistance, low modulus of elasticity, flexibility, resistance to warping, chemical resistance, adhesiveness with substrates, and plating resistance.

Abstract: In a surface-mounted optical transmission module, a laser diode serving as a light emitting device that converts an electric signal into an optical signal, and an optical waveguide serving as an optical transmission line that transmits and outputs the optical signal from the laser diode are placed on a substrate. A driving device for controlling the driving of the laser diode is placed at a predetermined position on the upper surface of the optical waveguide element, which is on the same side as an optical waveguide element (on the downstream side in the optical-signal transmitting direction) relative to the laser diode. This configuration eliminates the necessity of placing the driving device at a position distanced from the laser diode, whereby the size of the optical transmission module can be reduced, and this allows the optical transmission module to transmit optical signals at high speed.

Abstract: A planar optical waveguide is formed with an optical circuit having an inclined groove. A reflection filter is installed on the inside of the inclined groove 3 crossing a plurality of optical waveguides. Reflected light from the reflection filter is detected by an array of photodetectors to monitor the optical intensity of the signal light. The photodetector array is held by a sub-mounting substrate disposed at the top side of the optical circuit so that a mounting face of the photodetector array is inclined at an angle a (0°<?<90°) with respect to the top surface of the optical circuit such that the reflected light from the reflection filter is made incident onto a light incident face of the photodectors at a predetermined angle ?. The optical waveguide module is capable of monitoring the optical intensity correctly regardless of the polarization state of the signal light.

Abstract: An optical receiver, small and inexpensive, is used for a WDM transmission system in place of a wavelength demultiplexer. In the receiver, a light-transmitting medium and a photodiode (PD) are placed on the same substrate, a wavelength-selecting filter is attached perpendicularly or obliquely to the end face of or to a cut section at the midpoint of the medium, the filter transmits only the assigned wavelength included in the incident light having multiplexed wavelengths, and the PD detects only the assigned wavelength. With an optical fiber, the fiber can be housed in a ferrule. In this case, the filter is inserted into a filter-supporting hole provided at a midpoint of the ferrule, the ferrule is fixed in a groove formed on the substrate, and an optical pathway-changing groove formed on the substrate reflects light having emerged from the optical fiber to introduce it into the PD.

Abstract: The present invention relates to an optical module with a small size and improved mass-productivity. The optical module comprises a fiber stub including an optical fiber, a sleeve containing the fiber stub, and a semiconductor optical amplifying device. A Bragg fiber grating is formed in the optical fiber. The optical fiber is secured in the ferrule. The optical amplifying device and the grating form a laser cavity. Only a part of the hollow portion of the sleeve is filled with the fiber stub. One end face of the optical fiber is disposed at one end of the sleeve. The other end of the sleeve is hollow. The optical module acts as an optical receptacle. An optical plug can be inserted into the hollow end of the sleeve. This enables the laser light to be introduced into an external optical device.

Abstract: A photodiode (PD chip) includes a substrate, an absorption layer, a p-n junction in the absorption layer, a passivation film for protecting the end of the p-n junction, a p-electrode, and an n-electrode. The passivation film is covered with a protective layer composed of an insulative resin and having a thickness larger than that of the passivation film such that the passivation film of the PD chip fixed to the Si wafer and hence the p-n junction are not damaged or contaminated when an Si wafer including a number of horizontally and vertically arranged chip units, each having a V-groove for fixing an optical fiber, a marker, and a metallized pattern, is diced. Thus, a low-cost optical receiver module that does not generate dark current can be produced.

Abstract: The detection light reflection function is given to PLC type LD, PD or LD/PD modules having light guides and optoelectronic chips (LD, LED, PD or APD) by forming a grating on the light guides which selectively reflects only the detection light.

Abstract: An optical transmitter comprises an optical transmission unit having a semiconductor optical amplifier, and an optical connector having a plurality of diffraction gratings. The plurality of diffraction gratings are arranged in parallel with each other and partly reflect respective wavelengths of light different from each other. The optical connector is connected to the optical transmission unit such that light from the semiconductor optical amplifier is incident on one of the plurality of diffraction gratings.

Abstract: In a planar optical waveguide type optical circuit 1, a reflection filter 4 is installed on the inside of a inclined groove 3, which is formed so as to cross optical waveguides 2n. Reflected light from the reflection filter 4 is detected by photodetectors 61n of a photodetector array 60, thereby the optical intensity of the signal light is monitored. As for the photodetectors 61n, there is adopted a constitution such that a sub-mounting substrate 70 is disposed at the top side of the optical circuit 1 to hold the photodetector array 60 with a photodetector mounting face 71, which is inclined at an angle ? (0°<?<90°) with respect to the top surface of the optical circuit 1 such that the reflected light from the reflection filter 4 is made incident onto a light incident face 63 of the photodetectors 61n in the photodetector array 60 at a predetermined angle ?.

Abstract: The light-emitting device has a fiber stub part, a semiconductor optical amplifying device, a photodiode, and a bench as its main parts. The fiber stub part is composed of a ferrule and a grating fiber. The fiber stub part and the semiconductor optical amplifying device are mounted on the bench, and optically coupled together. An optical cavity is composed of the light-reflecting face of the semiconductor optical amplifying device and the diffraction grating of the grating fiber. The light-emitting device, which does not use a pigtail fiber, can be downsized and can provide laser light with a desired wavelength.

Abstract: A photodiode (A) comprises a substrate, a light receiving layer having a band gap wavelength and including a pn-junction and at least an absorption layer having a band gap wavelength ?g. One of the absorption layers is sandwiched between the substrate and the light receiving layer, the band gap wavelength ?g of the absorption layer is shorter than the receiving signal wavelength ?2 but longer than noise wavelength ?1(?1<?g<?2). Otherwise a photodiode (B) has two absorption layers epitaxially made on the substrate. One absorption layer is formed on the top surface of the substrate. The other absorption layer is formed on the bottom surface of the substrate. The absorption layers annihilate the noise ?1. The PD has no sensitivity to ?1.

Abstract: A parallel multichannel LD/PD module comprising a bench, a set of M (M; channel number) curving lightpaths (lightwaveguides or optical fibers) having a narrow width region, a width enlarging region and a wide width region which are formed upon the bench, a wavelength selective filter provided at the wide width region for reflecting receiving beams upward, a set of photodiodes installed in front of the wavelength selective filter at the wide width region above the bench and light emitting devices mounted behind the ends of the lightpaths with a wide pitch for yielding transmitting beams. Propagating in outer M-channel element fibers of a ribbonfiber, receiving signal beams go into the lightpaths via the narrow width region, expand horizontally in the width enlarging region, arrive at the wide width region, and are reflected by the wavelength selective filter upward. The receiving beams go into the photodiodes which yield photocurrents in proportion to the powers of the receiving beams.

Abstract: An optical transmission module includes plural optical transmission means (optical waveguides) whose end portions are exposed on a first end face thereof, and at least one of an optical transmitting section and an optical receiving section to each of which some of the optical transmission means are optically coupled. The remaining optical transmission means are exposed on a second end face opposed to the first end face. Only some of the plural optical transmission means are designed to have a communication facility at some position in the longitudinal direction thereof, while the remaining optical transmission means are designed to have the communication facility by being connected to post-stage optical transmission modules in the longitudinal direction. By multistage-connecting these optical transmission modules, plural optical transmission means and optical transmission modules can be collectively connected at a narrow frontage.

Abstract: In an optical transmitter in which the amount of light of an LD is monitored by a monitor PD, and the power of the LD is kept constant by feedback, the present invention aims to provide an optical transmitter that is suitable for size and cost reductions while being able to input a greater amount of the LD light of to the monitor PD, and that is capable of performing higher-bit-rate transmission. The present invention is characterized in that a concave groove is formed in a substrate, and the monitor photodiode is mounted on a slanted face of the concave groove, and the light of the LD that is oppositely and horizontally disposed is received directly by the monitor the LD photodiode.

Abstract: In a surface-mounted optical receiver module comprising a substrate, a photodiode serving as a light receiving device for converting an optical signal into an electrical signal, an optical waveguide serving as an optical transmission line for transmitting the optical signal to the photodiode, and an amplifier device for amplifying the electrical signals, the amplifier device is placed at a predetermined position on the upper surface of the optical waveguide element, which is on the same side as an optical waveguide (on the upstream side in the optical-signal transmitting direction) relative to the photodiode. This configuration eliminates the necessity of additionally securing a space to provide the amplifier device, whereby the size of the optical transmission module can be reduced, and this allows the optical receiver module to receive optical signals at high speed.

Abstract: An external cavity semiconductor laser comprises a grating fiber and a semiconductor optical amplification element. The grating fiber has a Bragg grating and an optical waveguide. The Bragg grating has a frequency fFG and exhibits a maximum reflectivity thereat. The Bragg grating is optically coupled to the optical waveguide. In the external cavity semiconductor laser. The grating fiber is determined such that an oscillation frequency fLD satisfies 0<fFG−fLD<20 GHz  (1) According to the structure of the external cavity semiconductor laser, the occurrence of mode hopping is reduced within a frequency range defined by expression (1).

Abstract: A multichannel parallel LD/PD module comprising a bench, a plurality of lightpaths having an initial narrow width region, an intermediate width enlarging region and a final wide width region, a plurality of photodiodes or a photodiode array mounted on the narrow width region, a wavelength selective filter formed on the narrow width region for selectively reflecting receiving beams, a plurality of light emitting devices fitted behind rear ends of the lightpaths on the bench. Traveling in element fibers in an outer ribbon fiber, receiving signal beams go into the lightpaths via front ends and are reflected by the wavelength selective filter slantingly upward at the narrow width region. The reflected beams go into the photodiodes and are converted into photocurrents in proportion to the receiving signals.

Abstract: An optical communication device having an optical fiber, other optical parts, a transparent potting resin with a refractive index akin to the fiber and a pressurizing element with extra pressure in contact with the potting resin for applying positive pressure upon the potting resin with a predetermined temperature range. The present optical communication device can solve the problems of decline of sensitivity of PDs and instability of the oscillation of LDs in a low temperature region between −40° C. and 0° C. after a heat cycle test.