Nec Corporation

Nec Research Institute, Inc.

Kenichi Kasahara

Yoshiharu Tashiro

Ichiro Ogura

Shigeru Kawai

Keiichi Kubota

Mitsunori Sugimoto

Yao Li

Richard A Linke

Takahiro Numai

Shigeo Sugou

Yoshiharu Toshiro

Yuh-Dauh Lyuu

A mesh-connected tree (MCT) interconnect topology network which is a two-dimensional interconnect topology combining aspects of a conventional tree-network and a two-dimensional nearest-neighbor mesh network is implemented as a planar optical interconnect network.

Planar optical mesh-connected tree interconnect network

The invention provides a method of fabricating two dimensional semiconductor surface emitting laser and photo detector arrays for wavelength division multiplexing optical interconnections. A first stacked multiple layer structure on a first semiconductor substrate. An intermediate layer is grown on the first stacked multiple layer structure. A second stacked multiple layer structure is grown on the intermediate layer. A second semiconductor substrate is adhered on a top of the second stacked multiple layer structure by a heat treatment thereby a wafer is grown in successive growth processes to receive a selective wet etching so that the intermediate layer only is selectively etched to separate the first and second stacked multiple layer structures from one another, followed by forming surface emitting laser arrays and photo detector arrays on the first and second semiconductor substrates respectively.

Method for fabricating semiconductor laser and photo detecting arrays

A semiconductor optical device including multilayer semiconductor device regions formed on a surface of a semiconductor substrate which act as an optical device respectively, and diffraction gratings formed on a back of the substrate optically coupled with at least one of said regions through the substrate. The regions have a function such as light emitting, light receiving, light amplification or light switching. The regions and gratings can be respectively formed on the surface and the back, monolithicaly, and polishing of the substrate provides a suitable thickness so that the regions and the gratings may be optically coupled with each other. The regions and gratings may be arranged at the optimum positions in the direction parallel to the substrate. Extremely precise alignment of its components and many channels can be easily obtained with compact size.

Semiconductor optical device having device regions and diffraction

A surface emitting photonic switching structure includes an intermediate semiconductor structure having pn junction is sandwiched between a first semiconductor multi-layer film mirror (DBR1) and a second semiconductor multi-layer film mirror (DBR2). A pair of electrodes are provided to the intermediate semiconductor structure and the pn junction therein is applied with reverse bias voltages for changing the effective optical length of the intermediate semiconductor structure so as to change transmission wavelength of light incident on the second multi-layer film mirror or the first multi-layer film mirror. The structure can be two-dimensionally integrated, be compact and is capable of operating with low voltages.

Surface emitting photonic switching structure

A first insulation film is provided on the x axis side surfaces of a mesa on a substrate of a surface emitting semiconductor laser, and a second insulation film is provided on the y axis side surfaces of the mesa. The x and y axes are orthogonal to each other. The first and second insulation films are formed at different temperatures, so that stress applied to an active layer is different between the x and y axis directions. Consequently, the polarization of an output light is controlled to be on a selected axis from the x and y axis directions.

Surface emitting semiconductor laser

A surface-normal optoelectronic device is provided which includes a first semiconductor layer of a first electroconductive type, a second semiconductor layer of a second electroconductive type having a polarity inverse to that of the first electroconductive type, a semiconductor active layer, a third semiconductor layer of the first electroconductive type, and a fourth semiconductor layer of the second electroconductive type, formed on a semiconductor substrate. The second and third layers are larger in forbidden band width than the active layer, said second layer is smaller in forbidden band width than a part of the first layer contacting the second layer, and the third layer is smaller in forbidden band width than a part of the fourth layer contacting the third layer. High resistance regions are formed vertically passing through the active layer, to surround its light-emitting region and to have a resistance higher than that of that region. By providing such high resistance regions, an ineffective current to be drained out of the light emitting region can be outstandingly reduced. By setting the forbidden band widths as noted, carriers and light can be easily confined. Preferably, the first and fourth layers include layers serving as a reflecting mirror, the active layer being sandwiched by these layers. Laser emission is thereby rendered possible.

Semiconductor surface light emitting and receiving heterojunction device

A driving method for a pnpn semiconductor device includes the steps of applying a voltage higher than a holding voltage of the pnpn semiconductor device to an anode electrode thereof, supplying a control signal light to the pnpn semiconductor device to set the pnpn semiconductor device into an ON state, and supplying an information signal light to the pnpn semiconductor device to emit an output light. The control signal light and the information signal light are time-sequentially supplied to the pnpn semiconductor device under the voltage applied thereto. An apparatus for carrying out the driving method includes a light information transmission input line that is branched into a plurality of lines, where a light detection circuit is coupled to at least one of the lines. A synchronous driving circuit applies voltage to the pnpn semiconductor device which is coupled to one of the other lines of the information transmission input line. The pnpn semiconductor device is driven by receiving light from the input line when the light detection circuit detects an address of the pnpn semiconductor device included in a light supplied from the light information transmission input line.

Driving method and apparatus for a pnpn semiconductor device

A semiconductor layer for reflecting an optical beam, the semiconductor layer includes a plurality of film pairs of narrow and wide band gap semiconductor films (21, 22) having a refractive index difference and narrower and wider band gaps, an intermediate semiconductor film (31) is interposed between the narrow and the wide band gap semiconductor films of each film pair and is made to have an intermediate film band gap which is varied so as to be equal to the narrower and the wider band gaps at its interfaces contiguous to the narrow and the wide band gap semiconductor films. The narrow band gap semiconductor film and a portion adjacent thereto in the intermediate semiconductor film are called a first composite layer and given a first total thickness which is approximately equal to a quarter of a first wavelength had by the optical beam in the first composite layer. The wide band gap semiconductor film and a remaining portion adjacent thereto in the intermediate semiconductor film are called a second composite layer and given a second total thickness which is approximately equal to a quarter of a second wavelength had by the optical beam in the second composite layer. Preferably, the intermediate semiconductor film should have a film thickness which is substantially equal to a width which a potential barrier has perpendicularly of the film pairs if the intermediate semiconductor film were absent. More preferably, absorption of the optical beam in the narrow and the wide band gap semiconductor films is taken into account on determining their thicknesses.

Semiconductor layer comprising cyclically stacked narrow, intermediate,

A matrix of optical functional devices are divided into plural device units. Each of the device units includes at least two optical functional devices having light transmitting coatings. The coatings have transmission factors which are different from each other. Light signals emitted through the coatings from the at least two optical functional devices in each unit are received by a corresponding light receiving device among light receiving devices arranged in a one-dimensional pattern. In each device unit optical functional devices to be driven are selected, so that a coupling degree between each device unit and the corresponding light receiving device is changed.

Optical interconnection apparatus

A semiconductor optical memory includes a gate layer composed of a p- first semiconductor layer, a p- or n- second semiconductor layer, and an n- third semiconductor layer provided between a cathode layer and an anode layer. Where the second layer is of n- type, an impurity concentration of the n- second semiconductor layer is lower than an impurity concentration of the n- third semiconductor layer, and a bandgap eneray of the n- third semiconductor layer is lower than bandgap energies of the cathode and anode layers. Where the second layer is of p- type, an impurity concentration of the p- second semiconductor layer is lower than an impurity concentration of the p- first semiconductor layer, and a bandgap energy of the p- first semiconductor layer is lower than bandgap energies of the cathode and anode layers. As a result, a response speed becomes as fast as several 100 Mb/s.

Semiconductor optical memory having a low switching voltage

At least one electric pulse having a predetermined voltage which is higher than a switching voltage for a pnpn semiconductor device and a predetermined width is applied across the pnpn semiconductor device. The electric pulse width is set not to turn the pnpn semiconductor device on. Consequently, a predetermined amount of carriers are accumulated in the pnpn semiconductor device. In this circumstance, a trigger light is supplied to the pnpn semiconductor device to be turned on. As a result, an energy of the trigger light is largely decreased as compared to a conventional method.

Method for driving a pnpn semiconductor device

A laser diode and an optical switching device are connected in parallel relative to a power supply. The optical switching device is turned on by receiving an input light, and stores the ON state, so that the laser device is turned off. As a result, an electric power consumption is decreased, the structure is simplified, and the adjustment becomes easy.

Optical logic device with PNPN detection and laser diode output

A space modulation matrix is composed of semiconductor transmittivity modulation elements arranged in a matrix pattern. A transmittivity of the transmittivity modulation elements is changed by supplying a light or applying a voltage greater than a switching voltage of the transmittivity modulation elements to a selected number of the transmittivity modulation elements, so that a space modulation is provided on the space modulation matrix, and is renewed by any number of times.

Semiconductor device for a space modulation matrix and method for

A circuit for driving a gated p-n-p-n device comprises a p and/or n-gate electrodes provided on a p and/or n-gate regions of a p-n-p-n device, and a rectifying device provided between the p or n-gate electrode provided on a gate region which is higher in its impurity density than the other gate region and an anode or cathode electrode of the p-n-p-n device and/or a resistance means provided between the p or n-gate electrode provided on a gate region which is lower in its impurity density than the other gate region. In the circuit for driving a gated p-n-p-n device, excess carriers are expelled from the p and/or n-gate electrodes through the rectifying device and/or resistance means to the external of the p and/or n-gate regions.

Circuit for driving a gated p-n-p-n device

An optical semiconductor device comprises cathode and anode regions, and a gate region having a forbidden band gap narrower than those of the cathode and anode regions. The gate region is sandwiched by the cathode and anode regions. The optical semiconductor device further comprises a plurality of windows for receiving and radiating lights so that the alignment of light axes can be easily performed for a plurality of input and output lights.

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Tokyo, Japan

Kenichi Kasahara