Nippon Electric Co., Ltd.

Nec Corporation

Tokyo Institute of Technology

Nippon Telegraph and Telephone Public Corporation

Nippon Selfoc Co., Ltd.

Kohroh Kobayashi

Ikuo Mito

Mitsuhiro Kitamura

Hikaru Kouta

Mikio Oda

Hisaya Takahashi

Kazuhisa Kaede

Shigeo Matsushita

Shigetoki Sugimoto

Roy Lang

Kaichirou Nakano

Tetsuhiko Ikegami

Optical elements (light sourcesor photodetectors) are arranged in a two-dimensional array, and the relative positional relationship between the optical elements and optical waveguidesis defined such that optical waveguidesextend between the optical elements in the two-dimensional array substantially parallel to substratefor increased parallelism. Micromirrorsare disposed in respective optical waveguidesto bend light beams through 90 degrees to realize a highly efficient optical coupling between the optical elements and optical waveguides. The optical waveguides are stacked in multiple stages, and light beams are lead to the optical waveguides in the multiple stacks through micromirrorsacross the stacked plane of the optical waveguides, thereby realizing parallel connection between the two-dimensional array of optical elements and a two-dimensional array of optical waveguides. There is thus provided a connection structure between the optical elements and optical waveguides, which is small in size and high in efficiency, and is of high parallelism.

Connection structure of two-dimensional array optical element and optical circuit

An optical bistable device comprising a semiconductor laser including a diffraction grating which diffracts light parallel to the grating for laser resonance and additionally diffracts a higher order Bragg beam perpendicular to the grating. An optical detector receives the higher order beam and produces an electrical signal which is used as a partial exciting current for the semiconductor laser. Thereby, the two optical ports of the laser can be used for other purposes.

Bistable optical device

A semiconductor laser for use as a bistable optical device in which an active semiconductor layer has corrugations of predetermined pitch on its surface and a semiconductor optical waveguide is formed on the corrugation. At least one end of the active layer is exposed at an oblique angle so that light in the active layer propagating along the direction of corrugation is reflected from the oblique face to a normal of the surface of the laser. Electrodes are provided above and below the active layer.

Optical bistable semiconductor laser producing lasing light in direction

A double-channel planar buried-heterostructure semiconductor laser diode (DC-PBH LD) has improved high frequency response characteristics due to lower p-n junction capacitance resulting from the interposition of a low carrier concentration blocking layer between p-n-p-n blocking layers of the DC-PBH LD structure.

Double-channel planar heterostructure semiconductor laser

A buried heterostructure semiconductor laser diode with improved efficiency, CW operating temperature and output characteristic is comprised of a semiconductor substrate of a first conductivity type and includes successively at least a first cladding semiconductor layer of the first conductivity type, an active semiconductor layer, and a second cladding semiconductor layer of a second conductivity type. The active semiconductor layer has a narrower bandgap than those of the first and second cladding semiconductor layers. The multilayer double heterostructure has a stripe geometry with channels formed along both sides of the stripe and extending down to the first cladding layer. A current blocking layer is formed on the multilayer double heterostructure except for the top surface of the stripe geometry, in order to block a current flow therethrough.

Double channel planar buried heterostructure laser

In an integrated optical semiconductor device wherein a stripe geometry laser diode is separated from a photodetector by an etched groove, the stripe region has a smaller width, such as 2 to 3 microns, than a carrier generating region of the photodetector. The stripe region is preferably rendered thicker than the carrier generating region, in which case the carrier generating region is more preferably made of a seimconductor material having a narrower band gap than the material of the stripe region. The stripe region may be defined by a buried mesa structure. Alternatively, the stripe region may be bounded transversely of a pair of heterojunctions therefor by a pair of channel-shaped regions of a semiconductor material having a wider bank gap than the material of the stripe region. In this event, the carrier generating region is divided into three parts by extensions of the channel-shaped regions. Most preferably, the carrier generating region has a light receiving end which is not parallel to a light emitting end of the stripe region. The light receiving end may be cylindrical.

Semiconductor laser having an etched mirror and a narrow stripe width,

A buried heterostructure laser diode and method for making the same wherein an active layer is provided in a semiconductor region forming a mesa stripe, and, except for the top surface portion of the mesa stripe, the side surface portion of the mesa stripe and the remainder are covered by a current-blocking layer. Furthermore, a current-confining layer covers only this current-blocking layer, and a clad layer covers the current-blocking layer and the top surface portion of the mesa stripe.

Buried heterostructure laser diode

An integrated laser array is disclosed in which a plurality of semiconductor lasers are integrated on a semiconductor multi-layer crystal that includes an active layer in which the band gap energy varies in one direction. By means of this arrangement a plurality of semiconductor lasers, which differ in their respective oscillating wavelengths over a relatively broad range, can be formed on a common substrate.

Semiconductor diode laser array

An optical multiplexer-demultiplexer consisting essentially of a light-focusing transmission body having a radially graded refractive index distribution and a reflection or transmission type diffraction grating. The transmission body is given an axial length approximately equal to an integral multiple of one quarter of the pitch of undulation of an off-axis input light beam as travelling through the transmission body while the diffraction grating is arranged on the axis of the transmission body at a distance approximately equal to an odd multiple of one quarter of the pitch of beam undulation from one end face of the transmission body which is normal to the axis. A composite light beam directed into the transmission body is dispersed by the diffraction grating into wavelength components, which are separately focused to be extracted as through respective optical fibers. The device needs no separate optical elements such as reflecting mirrors or an independent diffraction grating and is not only particularly compact in size and stable on account of its integral structure but is capable of a high degree of multiplexing.

Optical wavelength-division multiplexing and demultiplexing device

A semiconductor laser device in which a part of the laser output is reflected from an external reflector and injected into the laser element with a delay that is less than the relaxation oscillation period of the laser pulse output.

Light self-injecting semiconductor laser device

The invention contemplates an improved means for coupling plural optical fibers to a single optical fiber, whereby coupling losses may be held to relatively low magnitude. Each of the plural optical fibers is fitted to a first end of an elongate light-transmitting body having an elongate body axis about which the refractive index decreases approximately proportional to the square of the distance from the axis, and these bodies are grouped with their body axes is close and substantially parallel array. The opposite ends of the light-transmitting bodies all spaced from and face the end of the single optical fiber, with the optical axis of said single end aligned with the elongation of the group; and an optical lens is placed on the optical axis between the group and the single-fiber end, with the latter near the focal plane of the lens.

Growing community of inventors

Tokyo, Japan

Kohroh Kobayashi