Hitachi, Ltd.

Hitachi Cable, Inc.

Sharp Kabushiki Kaisha Corporation

Hirobumi Ouchi

Hiroshi Matsuda

Kazuhiro Ito

Makoto Morioka

Kazuhiro Kurata

Shigeru Nakamura

Yukio Kurata

Naoki Chinone

Masahiro Ojima

Takashi Kajimura

Yuichi Ono

Hisato Uetsuka

Tsukuru Ohtoshi

Takao Kuroda

Kohji Minami

Kazuyuki Nagatsuma

Mitsuhiro Mori

Masahiko Kawata

Yasutoshi Kashiwada

Hideyuki Takashima

Masahiro Ichiki

Makoto Horie

Ichiro Fujiwara

Toji Mukai

Takeo Takahashi

Ginro Takemura

Youichi Yasuda

Makoto Sakamoto

Yasushi Koga

A photocoupler according to the present invention includes: an optical waveguide including a substrate, at least a first dielectric layer provided on the substrate, the first dielectric layer having a tapered structure whose thickness varies in an x-direction in which light is propagated after coupling, and a second dielectric layer provided on the first dielectric layer; a light incidence component provided above the optical waveguide, which causes light incident thereon to be directed toward a surface of the optical waveguide at a prescribed angle; and a bonding section for bonding the light incidence component to the optical waveguide. The bonding section has an edge surface which makes contact with the surface of the waveguide in a straight line and has a portion which makes contact with neither the light incidence component nor the surface of the optical waveguide. The tapered structure of the first dielectric layer has a shape set such that a radiation pattern of light with a wavelength .lambda. output from the optical waveguide of the photocoupler fulfills the following expression:

Photocoupler and method for producing the same

An optical fiber type magneto-optical head is capable of realizing satisfactory reductions in size and weight of a movable portion of an optical head. An extinction-type form of the optical fiber type magneto-optical head comprises a first optical device for condensing a polarized light beam and leading the light beam into a polarization-maintaining optical fiber, a second optical device for focusing light emerging from the optical fiber into a beam spot on a magnetic recording medium, a detector for detecting via the optical fiber light reflected from the magnetic recording medium with a change in polarized state, and an azimuth rotator disposed between the second optical device and the optical fiber, wherein the azimuth rotator is designed so that the angle of optical rotation upon one pass therethrough is

Magneto-optical head employing optical fiber connected stationary and

An avalanche photodiode including a substrate, a first semiconductor region of a first conductivity type having a relatively large band gap, a second semiconductor region of a second conductivity type having a relatively large band gap, and a third semiconductor region of the first conductivity type having a band gap smaller than the band gap of the first and second semiconductor regions, is disclosed in which, in order to suppress an increase in dark current and to cause the avalanche photodiode to operate on a low voltage, a fourth semiconductor region equal in conductivity type to and larger in impurity concentration than the first semiconductor region is formed in the first semiconductor region at a position below a central portion of a pn junction formed between the first semiconductor region and the second semiconductor region. The avalanche photodiode formed with this structure has low-noise and low operation voltage characteristics.

Optoelectronic device

Disclosed is a photo-detective semiconductor device having, on a predetermined semiconductor substrate, at least a first semiconductor layer which exhibits a first conductivity type, a second semiconductor layer which is disposed on said first semiconductor layer, which has a forbidden band gap greater than that of said first semiconductor layer and which exhibits the first conductivity type, and a p-n junction which is formed by a region disposed in said second semiconductor layer and exhibiting a second conductivity type; characterized by comprising a third semiconductor layer which is disposed on said second semiconductor layer, which exhibits the first conductivity type and which has a surface protective function. The third semiconductor layer is usually made of a group III-V compound semiconductor of a quaternary system. By way of example, in a case where the first semiconductor layer is formed of InGaAsP and where the second semiconductor layer is formed of InP, the third semiconductor layer is made of InGaAsP, InGaAs or the like. A photo-detective semiconductor device of low dark current can be provided.

Photo semiconductor device

Disclosed is a semiconductor laser device having at least an optical confinement region which includes a first semiconductor layer, and second and third semiconductor layers holding the first semiconductor layer therebetween and having a greater band gap and a lower refractive index than those of the first semiconductor layer, the second and third semiconductor layers having conductivity types opposite to each other; characterized in that the relationship between a donor density (N.sub.D .times.10.sup.17 cm.sup.-3) of the n-conductivity type semiconductor layer in the second and third semiconductor layers and a proportion (.GAMMA..sub.n %) of an optical output existing in the n-conductivity type semiconductor layer relative to a total optical output of the laser is set at N.sub.D .times..GAMMA..sub.n .gtoreq.500. Noise characteristics are sharply improved.

Semiconductor laser device

An optical semiconductor device includes a light emitting element disposed on a silicon sub-mount having a light receiving element formed in a surface region. By virtue of integral arrangement of the light emitting element and the light receiving element, a single lens can be used for both optical transmission and optical reception, whereby an optical communication system can be manufactured very inexpensively. Further, transmission and reception can be carried out simultaneously.

Optical semiconductor device

A light detector device comprises at least one pair made up of a light sensitive photodiode and a light signal reading MIS transistor switch. The pair is formed on an insulating substrate such as sapphire. The source region of the MIS transistor switch is contiguous with a photosensitive pn junction of the photodiode. The source, drain and channel regions of the MIS transistor switch reach the insulating substrate, thereby reducing the area of pn junction of the MIS transistor and hence the junction capacitance so that high signal output is available from the photodiode with high S/N ratio.

Light detecting photodiode-MIS transistor device

A photo-semiconductor device includes an active region of semiconductor material in which carriers contributing to a photocurrent are generated by the irradiation of incident light. On one surface of the active region is formed a main junction towards which those carriers move. In the active region is buried an additional region to form at the interface between the additional and active regions an additional junction which attracts a substantial portion of thermally generated carriers. The remaining portion of the thermally generated carriers is partially recombined internally and partially attracted to the main junction. Thus, dark current is reduced.

Low dark current photo-semiconductor device

Growing community of inventors

Hino, Japan

Hirobumi Ouchi