Abstract: A measurement of nonlinear refractive index coefficient of an optical fiber with a Sagnac interferometer, comprises the steps of employing the optical fiber in a Sagnac interferometer, splitting a signal beam into two signals, launching the two split signals into the interferometer in opposite directions, combining and detecting the signals counter-propagated in the interferometer, and detecting the refractive index coefficient of the optical fiber in accordance with the difference between the two signal powers determined by a control beam. The quasi-static phase shift of the signal beam counter-propagating the same paths of the interferometer is induced by rotating the optical fiber loop of the interferometer. The present invention gives rise to little error because it does not require precise information about the pulse width of a used beam or a high-power light.

Abstract: A crystal growth method for a compound semiconductor is capable of forming a plurality of quantum wells (formed of a barrier layer having a large energy band gap and an active layer having a small energy band gap) on the compound semiconductor substrate. After etching a V-shaped groove having a (111) surface with a predetermined angle .theta.1 with respect to the (100) surface on the GaAs semiconductor substrate, the substrate is further etched by a hydrochloric solution and a solution of H.sub.2 SO.sub.4 :H.sub.2 O.sub.2 :H.sub.2 O=20:1 to cause the V-shaped groove walls to become a non-(111) surface having a lower predetermined slope angle .theta.2. The quantum wells then grown in the bottom of the V-shaped groove will be effectively disconnected from simultaneous growths on the side walls of the groove thus giving rise to closely controlled multi-dimensional quantum well structures.

Abstract: A vertical modulator with a dual mode distributed Bragg reflection (DBR), includes a pair of integrated elements using different wavelengths to provide functions of logical operation, data switching and wavelength conversion. The optical device includes a first optical structure operating at a first wavelength (.lambda..sub.1) and a second optical structure operating at a second wavelength (.lambda..sub.2). The first and second optical structures are formed over a semiconductor substrate. The first optical structure, which operates at the first wavelength (.lambda..sub.1), transmits its data to the second optical structure so that data corresponding to the second wavelength (.lambda..sub.2) can be output. Since the wavelength of input light is different from the wavelength of output light, the optical device serves as a modulator which performs a logic operation and switching function while carrying out wavelength conversion.

Abstract: An optical fiber laser is disclosed capable of generating an ultrashort pulse which has intensive energy and is stable against polarization by using a sagnac loop mirror and a Faraday rotator mirror, which includes a light pumping laser diode; an erbium doped fiber-added optical fiber; a wavelength division multiplier fiber coupler; a dispersion shifted fiber; and an optical fiber directional coupler; a nonlinear amplifier loop mirror; a second polarization controller; a linear mirror having a Faraday rotator mirror for rotating the polarization plane of a proceeding light wave; and a directional coupler being connected between the nonlinear amplifier loop mirror and the linear mirror.

Abstract: A wavelength division demultiplexing device, and a system using the device are disclosed, in which there is utilized a Pabry-Perot etalon using as a spacer layer a Kerr medium in which the refractive index is varied in accordance with the intensity of beams.

Abstract: A method for the manufacture of a single electron transistor (SET) in a vacuum state, wherein the SET operates in room temperature, comprises the steps of: approaching an Au tip of a scanning tunneling microscopy (STM) on top of a silicon-substrate having a silicon oxide layer on top thereof to maintain a distance from top of the oxide layer to end of the Au tip of the STM; forming an Au cluster on top of the oxide layer by using a low field evaporation method employing the STM, thereby forming a two dimensional island structure on top of the oxide layer, wherein the low field evaporation method employing the STM generates an electronic pulse between top of the oxide layer and end of the Au tip of the STM by applying a voltage to the Au tip of the STM; forming a source and a drain to both sides of the Au cluster in the two dimensional island structure, respectively, in such a way that the Au cluster in the two dimensional island structure maintains a gap with the source and the drain, thereby forming an elect

Abstract: Disclosed is a nonbiased bistable optical device and a method for fabricating the device, which has a semi-insulating GaAs substrate; a lower mirror having a plurality of reflecting layers which are repeatedly formed on said substrate at least more than twelve times, each of said reflecting layers having a first reflecting film having a first refractive index on said substrate and a second reflecting film a second refractive index different from the first refractive index; a first contact layer formed on the lower mirror; a first buffer layer formed on the first contact layer; a multiple quantum well(MQW) having a plurality of shallow layers which are repeatedly formed, each of said shallow layers having a barrier and a shallow quantum well; a second buffer layer grown on said MQW; and a second contact layer formed on said second buffer layer. The device has an excellent bistablity even without an external applied voltage.

Abstract: An all-optical signal processing apparatus of a non-linear fiber loop mirror type comprises a very high-speed all-optical switch that can be used as a reverse multiplexed switch in a high-speed time division optical communication. The apparatus includes a non-linear loop mirror for switching signal light by adjusting light using the non-linear effect of an optical fiber and the characteristics of a sagnac interferometer as the fundamental configuration. The all-optical switch is constructed so that another adjustment light having an appropriate time delay with respect to an existing adjusting light is additionally introduced in order to compensate for the limitation on the switching bandwidth imposed by the walk-off between adjusting and signal lights in a conventional non-linear optical fiber loop mirror. This compensates for the cross-talk of the noise signals due to DC components generated in the conventional apparatus.

Abstract: A bidirectional multi-channel all-optical ring network is provided, this network comprising a number of nodes linked by optical cables, each of the node comprising two of WDM/WDDM, packet switching devices, and a node controller, in which network a first optical signal group of wavelength channel signals (for example, .lambda.1, .lambda.3, .lambda.5, . . . ) are transferred in a counter-clockwise direction, and a second optical signal group of wavelength channel signals (for example, .lambda.2, .lambda.4, .lambda.6, . . .) are transferred in a clockwise direction, thereby allowing an optical data signal to be transmitted through the channel of shorter distance.

Abstract: A wavelength-varying multi-wavelength optical filter laser using a single pump light source is disclosed.

Abstract: A surface adsorption apparatus for dissociating H.sub.2 molecules into atomic hydrogen in a vacuum vessel and adsorbing the atomic hydrogen on a sample surface is disclosed. A vacuum tube is mounted in the vacuum vessel. A nozzle is connected to the vacuum tube having a plurality of bent portions. A heating member receives electrical power from a power supply source and heats the nozzle to a predetermined temperature. A heat shielding member is located in a path of the atomic hydrogen between one end of the nozzle and the sample surface for shielding the sample surface from heat radiating from the nozzle. The H.sub.2 molecules collide with inner wall surfaces of the bent portions to be readily dissociate into the atomic hydrogen. The atomic dissociated hydrogen propagates toward the sample surface and is adsorbed on the sample surface. Since the nozzle comprises bent portions, H.sub.2 molecules frequently collide with inner wall surfaces of the nozzle to readily dissociate into atomic hydrogen. The H.sub.

Abstract: A metal/semiconductor junction Schottky diode optical device using a distortion grown layer is described. A plurality of GaAs mirror and AlAs mirror layers are periodically grown on a semi-insulating GaAs substrate. An n+ or p+ semiconductor layer is formed on the GaAs mirror and AlAs mirror layers. A GaAs buffer layer is formed on the semiconductor layer to grow a Schottky metal layer serving as an electrode and a mirror. A multiple quantum well structure having an electro-optical absorption characteristic is positioned between the semiconductor layer and Schottky metal layer, for constructing a diode with the metal layer/multiple quantum well structure. At least a part of the mirror layers and diode are formed with a layer in order to have resonance and non-resonance conditions between the metal layer and mirror layers. The substrate on which the diode is formed has an opposite side formed with an optical non-reflective layer.

Abstract: A fiber-optic address detector comprises fiber-optic delay lines on one surface of which a metal thin film is evaporated, the fiber-optic delay lines being connected in a melting state to fiber-optic couplers, wherein inputting address photonic signals are tapped by the inputting fiber-optic couplers, reflected by the metal thin films at the end portion of the fiber-optic delay line and then re-combined by the inputting fiber-optic coupler, whereby it can reduce the number of the fiber-optic coupler used in the conventional fiber-optic address detector to one half as well as obtain the same address detection effect.

Abstract: Disclosed is an ultrafast optical switching device having two types of multiple quantum well structures to be connected with each other, the device comprising a semi-insulating substrate; and a first and a second multiple quantum well structure formed sequentially on the substrate and united with each other to produce a double-junction multiple quantum well structure. Each of the multiple quantum well structures has nonlinear optical effects and two life time constants present while switching off in the device. One of the life time constants corresponds to a short life time constant to be determined dependent on electrons in the double-junction multiple quantum well structure and the other of the life time constants corresponds to a long life time constant to be determined dependent on holes and lattices therein.

Abstract: The present invention relates to planar integration of an optical system. The optical system is an integration of a crossover switching network having several optical elements such as mirrors, lenses, beam splitters etc., spatially separated on a single wafer using an acute-angle prism array disposed on the surface of a substrate in which the optical elements are integrated.

Abstract: A method for epitaxially growing a layer of III-V material on a wafer of a material such as silicon comprises the steps of placing the wafer (16') in a first ultra-high vacuum chamber (11), and epitaxially growing a transition layer such as germanium on the wafer. An intermediate high vacuum chamber (13) is used to transport the wafer 16' to a second ultra-high vacuum chamber (12), and the second chamber (12) is used to epitaxially grow a layer of III-V material over the transition layer. Gate valves (33 and 15) are sequentially opened and closed to that the second vacuum chamber (12) cannot be contaminated by gases or particles from the first vacuum chamber (11). Wafer transport from chamber (11) to (13) is achieved without exposure to the atmosphere or to significant pressure changes thus avoiding the waste of transfer time or the formation of native oxide on the wafer surface.