National Institute of Advanced Industrial Science and Technology

Hitachi Cable, Inc.

Keio University

Fujitsu Corporation

Agency of Industrial Science and Technology

National Institute of Advanced Industrial Science

Hitoshi Kawashima

Hisato Uetsuka

Kazuhiro Ikeda

Masahiko Mori

Hiroshi Ishikawa

Hiroyuki Tsuda

Shu Namiki

Ken Tanizawa

Toshifumi Hasama

Keisuke Sorimoto

Keijiro Suzuki

Kenji Kintaka

Suguru Akiyama

Takeshi Matsumoto

Hiroyuki Matsuura

Haruhiko Kuwatsuka

Toshiro Tani

Satoshi Suda

Guangwei Cong

Fumio Sasaki

Shunsuke Kobayashi

An optical amplifier includes a polarization splitter, a polarization rotator, first and second optical couplers, and first and second semiconductor optical amplifying devices. The TE polarized wave of light split by the polarization splitter is input to a first input port of the first optical coupler. The TM polarized wave of the split light is converted into a TE polarized wave by the polarization rotator to be input to a second input port of the first optical coupler. First light and second light output from a first output port and a second output port of the first optical coupler are amplified by the first semiconductor optical amplifying device and the second semiconductor optical amplifying device to be input to a first input port and a second input port of the second optical coupler, respectively. Third light is output from an output port of the second optical coupler.

Optical amplifier and optical switch device

Provided is a driving device for PWM control of voltage pulses for controlling the temperature of a heater in a phase controller, the driving device being capable of increasing the response speed of an optical element such as an optical switch. Phase controllers include first and second heaters for changing the temperatures of first and second optical waveguides extending in parallel. Driving devices include pulse generation circuits that generate voltage pulses to apply to the first and second heaters. To start raising the temperature of the second heater, the pulse generation circuit generates a first voltage pulse and consecutive second voltage pulses to apply to the second heater with zero voltage pulse being applied to the first heater, the first voltage pulse having a long pulse width and the second voltage pulses following the first voltage pulse and having a shorter pulse width than the first voltage pulse.

Driving device and driving method for phase controller, and optical switch

A conventional optical switching engine has difficulty in producing a universal multiport switching engine being capable of (i) programmatically changing regions to be switched, (ii) generating no wavelength dependent loss, (iii) having a small Walk-off, and (iv) being usable for small to large light beams. Produced is a light beam deflecting element in which a polarization grating is fitted in parallel on an N&#xd7;M transmissive birefringence modulator formed such that a transmissive variable half-wavelength liquid crystal plate is divided into rectangular extreme small pixels, and many N and M pixels thus obtained are respectively arranged in X and Y axes directions in a matrix form, the polarization grating being a grating in which a period &#x2227; changes in an X' axis direction (direction to which a birefringence axis rotates) in accordance with a wavelength width of light.

Light beam deflecting element, wavelength-selective cross-connect device using same, and optical cross-connect device

To provide a waveguide type wavelength domain optical switch which makes it possible to use a cheap lens, makes it possible to correct aberration of the demultiplexed wavelengths produced in a plurality of waveguide type demultiplexing circuits, a wavelength domain optical switch is provided with: an integrated element formed by laminating three or more waveguide type demultiplexing circuits; a first lens for collecting light emitted from the integrated element; a polarization separation element for separating light emitted from the first lens into X polarization and Y polarization and emitting the X polarization and the Y polarization at different angles; a second lens for collecting the X polarization and the Y polarization; a first reflective optical phase modulator for reflecting the collected X polarization and Y polarization at any angles; a &#xbd;-wavelength plate disposed between the second lens and the first reflective optical phase modulator in order to make polarization directions of the X polarization and the Y polarization identical; and a second reflective optical phase modulator for inputting light from the first reflective optical phase modulator into one of the waveguide type demultiplexing circuits.

Wavelength domain optical switch

An optical waveguide-type wavelength domain switch includes a waveguide-type multi/demultiplexing device laminate comprising three or more laminated waveguide-type multi/demultiplexing devices, a lens system positioned on a demultiplex side of the waveguide-type multi/demultiplexing device laminate, and a reflective optical phase-modulating cell positioned on an opposite side of the waveguide-type multi/demultiplexing device laminate to the lens system. The lens system includes a lens alignment composed of plural lenses in one-to-one correspondence with the waveguide-type multi/demultiplexing devices and having a light-collecting or collimating function in the lens-aligning direction, an image-magnifying optical system having an N:1 (N&#x3e;1) image-magnifying function arranged on the optical phase-modulating cell side of the lens alignment, an f-f lens (Y) arranged on the optical phase-modulating cell side of the image-magnifying optical system, and having a light-collecting or collimating function in the same direction as the lens-aligning direction of the lens alignment, and an f-f lens (X) having a light-collecting or collimating function in a perpendicular direction to the lens-aligning direction of the lens alignment.

Optical waveguide-type wavelength domain switch

A dielectric dispersion determining method applying a transient grating method. The transient response of a sample is observed by the transient grating method using a femtosecond ultrashort visible optical pulse. A vibrational waveform b(t) is determined such that its square b(t).sup.2 replicates vibrational components observed in the transient response. The vibrational waveform b(t) is converted into b(.omega.) through the Fourier transform. The dielectric constant .epsilon.(.omega.) is obtained by substituting the converted value for b(.omega.)/.omega..sup.2 on the right-hand side of the following equation (1) derived from Maxwell's equations. The dielectric constant and/or refraction index can be directly obtained from the transient response to the femtosecond ultrashort visible optical pulse without passing through the dispersion relation which leaves some ambiguity in its definition. ##EQU1##

Dielectric dispersion determining method in terahertz region using

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Tsukuba, Japan

Hitoshi Kawashima