Abstract: A jointing holder for an optical module for single-fiber bidirectional communication comprises a unitarily structured cylindrical body that has the following portions: (a) an optical fiber-fixing portion for securely holding an optical fiber for transmitting multiwavelength light bidirectionally, (b) a semiconductor laser-fixing portion for securely holding a semiconductor laser for emitting outgoing light ?1, (c) a photodiode-fixing portion for securely holding a photodiode for receiving incoming light ?2, (d) an optical path-forming space for optically coupling the optical fiber, the semiconductor laser, and the photodiode, and (e) in the optical path-forming space, an optical filter-fixing face for securely holding an optical filter for separating multiplexed wavelengths. The jointing holder enables the optical module to reduce the number of components, to be miniaturized, and to reduce the dimensional deviation at the time of the assembly, enabling high-precision assembly.

Abstract: Disclosed is a photodiode array which includes a plurality of p-i-n photodiodes arrayed on a semi-insulative semiconductor substrate, each photodiode including an n-type semiconductor layer grown on the substrate, an i-type semiconductor layer grown on the n-type semiconductor layer, a p-type semiconductor layer grown on the i-type semiconductor layer, an n-type electrode provided on the n-type semiconductor layer in a region exposed by partially removing the p-type semiconductor layer and the i-type semiconductor layer, and a p-type electrode provided on the p-type semiconductor layer. A trench is provided between the two adjacent photodiodes by partially removing the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer. Consequently, the size and pitch of the photodiodes can be decreased and crosstalk between the photodiodes can be reduced. Also disclosed is an optical receiver device including the photodiode array.

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: Disclosed is a photodiode array which includes a plurality of p-i-n photodiodes arrayed on a semi-insulative semiconductor substrate, each photodiode including an n-type semiconductor layer grown on the substrate, an i-type semiconductor layer grown on the n-type semiconductor layer, a p-type semiconductor layer grown on the i-type semiconductor layer, an n-type electrode provided on the n-type semiconductor layer in a region exposed by partially removing the p-type semiconductor layer and the i-type semiconductor layer, and a p-type electrode provided on the p-type semiconductor layer. A trench is provided between the two adjacent photodiodes by partially removing the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer. Consequently, the size and pitch of the photodiodes can be decreased and crosstalk between the photodiodes can be reduced. Also disclosed is an optical receiver device including the photodiode array.

Abstract: An optical module for inputting and outputting light in a direction of a predetermined axis, and a method of manufacturing the optical module are provided. The optical module includes a stem having a mount and a principal surface crossing the predetermined axis. The mount has a first mounting surface, a second mounting surface, and an optical path. An optical filter is attached to the mount. A semiconductor light emitting device emitting light of a first wavelength is disposed on the first mounting surface and is optically coupled to the optical filter. A semiconductor light receiving device being responsive to light of a second wavelength is positioned on the second mounting surface in alignment with the optical path and is optically coupled to the optical filter through the optical path, thereby receiving the light of the second wavelength from the optical filter.

Abstract: In an optical communications module comprising one or more dielectric substrates equipped with an optical transmitter section, an optical receiver section or an optical transceiver section, and a chassis encasing all of them, a metal part is formed on one side of at least one of the dielectric substrates such that the metal part constitutes the whole or a part of the exterior surface of the chassis so that the length of heat conduction from a dielectric substrate with heat-generating components installed thereon can be minimized so as to efficiently release heat through the metal part to outside, curbing a temperature increase within the chassis. Thus, the optical communications module can exhibit excellent performance.

Abstract: 250 ?m is the standardized pitch H of the prevalent multichannel ribbonfibers. Current laser diodes and photodiodes have a size larger than 300 ?m. Curving lightpaths made on a silicon bench for reconciling the chip size with current ribbonfibers causes bending power loss, optical crosstalk and difficulty of production. Linear parallel lightpaths with a width d for more than one chip site are produced on a bench with a pitch E which is equal to the pitch H of the multichannels. Optoelectronic device chips with a width W satisfying an inequality E<W<2E?d are mounted on the lightpaths at spots which are different from neighboring chips in the longitudinal direction.

Abstract: An optical communications module in which electrical crosstalk is reduced. The term “optical communications module” represents a surface-mounting-type optical tranceiver, transmitter, or receiver module. The optical communications module has a following structure. (a) An Si substrate carries at least one signal-transmitting section comprising an LD, at least one signal-receiving section comprising a PD, or both together with other components. (b) An insulating substrate is bonded to the back face of the Si substrate. (c) A separating groove separates the Si substrate along the or each boundary line between the sections in order to prevent an AC current flowing through the Si substrate. To attain this object, the separating groove is provided from the top surface of the Si substrate to some midpoint of the insulating substrate.

Abstract: An optical data link includes a circuit board and an optical module component. The circuit board includes first and second mounting sections on a principal plane thereof. A step is formed between the first mounting section and the second mounting section. The first mounting section has the optical module component, and the second mounting section has an electron device. The optical module component includes a mounting component, a semiconductor optical device, and an optical transmission medium. The semiconductor optical device of the optical module component is electrically connected to the electron device, and is mounted on a first region of the mounting component. The optical transmission medium is supported by a second region of the mounting component, and is optically coupled with the semiconductor optical device.

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: An optical receiver is provided with an optical-signal-receiving section and a controlling section. The optical-signal-receiving section incorporates a photodetector. The photodetector has an APD. Through a passivation film, a photoconductor is placed on a portion of a surface of the APD which remains unoccupied by an optical-signal-receiving area of the APD. When this structure is employed, the signal for controlling the avalanche multiplication factor of the APD can be obtained from the photoconductor. Consequently, the signal can be obtained with a simple structure. Furthermore, the photoconductor has a good linearity of the output current even to a weak lightwave. As a result, the output current I for controlling the avalanche multiplication factor of the APD can be obtained with high accuracy.

Abstract: A sub-mount for fixing a photodiode is provided with an opening for transmitting an light, which is incident from below a light receiving portion of the photodiode. A wavelength selective filter having a wavelength selective function via a dielectric multilayer film is fixed to the opening for transmitting the incident light. Further, a light shading structure for shading scattering light incident from the side of the photodiode is provided and the whole light-receiving-portion-side surface is covered by potting with an opaque resin for absorbing scattering light incident from the light-receiving-portion-side surface of the photodiode, whereby an optical receiver excellent in wavelength selectivity is formed.

Abstract: An optical communication module having a roughened bottom of a silicon bench for suppressing optical crosstalk. The roughened bottom prevents stray laser beams from reflecting toward a photodiode. The roughened bottom is further covered with a photoabsorbent resin, pigment or adhesive for absorbing the stray laser beams at a bottom. A cladding of a lightwaveguide are narrowed and are painted with a photoabsorbent resin, pigment or adhesive for absorbing horizontally stray beams propagating in the cladding.

Abstract: The present invention provides an optical receiver that uses an avalanche photodiode (APD) whose multiplication factor m is controlled to compensate the temperature dependence thereof. An optical module of the present invention includes a light-receiving device in addition to the APD. The light-receiving device may be a semiconductor thin film or a PIN photodiode, and is disposed in front of the APD. Accordingly, the light-receiving device receives a portion of signal light, and transmits a rest portion thereof. The APD receives the rest portion of the signal light. The bias voltage applied to the APD is so controlled that a first photocurrent generated in the light-receiving device and a second photocurrent generated in the APD maintain a constant ratio.

Abstract: An optical receiver includes an avalanche photodiode (APD) having a light-receiving area provided on a face of a first substrate, the light-receiving area receiving a part of signal light; a photodetector having a light-receiving area provided on a face of a second substrate, the light-receiving area receiving the other part of the signal light; and a mounting member having a principal plane on which the APD and the photodetector are mounted. Due to this structure, crosstalk between the APD and the photodetector does not occur and an avalanche multiplication factor of the APD can be controlled on the basis of the output current of the photodetector.

Abstract: An inspection apparatus for an optical transmission device selects an optical path in accordance with the wavelength of an optical signal transmitted from the optical transmission device and displays an indication of the wavelength of the selected optical signal according to an electrical signal. Thus, an optical transmission device used for single-optical-fiber bidirectional transmission easily can be checked as to whether it is provided for a subscriber or for a central station using different wavelengths.

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: An optical receiver includes a PIN photodiode (PIN-PD) having an incident surface for receiving signal light, the PIN-PD transmitting a part of the signal light to the surface opposite to the incident surface, and an avalanche photodiode (APD) having an incident surface for receiving light transmitted through the PIN-PD. In the optical receiver, the ratio of the quantity of signal light detected by the PIN-PD and the ratio of the quantity of signal light detected by the APD are not affected by the polarization state of the signal light incident on the optical receiver, and accordingly the avalanche multiplication factor of the APD is suitably controlled on the basis of the signal light detected by the PIN-PD.

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: An optical receiver includes a light-receiving part and a control part. The light-receiving part includes an APD, a PIN-PD, and a branching optical device. First signal light is incident on the light-receiving part and is divided into second signal light and third signal light which are incident on the APD and the PIN-PD, respectively, by the branching optical device. Due to this structure, the third signal light is incident on the PIN-PD without the quantity thereof being varied depending on the polarization state of the first signal light. The control part generates a supply voltage at which a desired avalanche multiplication factor is obtained in the APD on the basis of the output current from the PIN-PD. According to the above-described structure, the avalanche multiplication factor of the APD is accurately controlled on the basis of the output current of the PIN-PD.