Keio University

Hitachi Cable, Inc.

National Institute of Advanced Industrial Science and Technology

Sophia School Corporation

Photonic Lattice, Inc.

Hiroyuki Tsuda

Hisato Uetsuka

Masahiko Mori

Hiroshi Ishikawa

Hitoshi Kawashima

Toshifumi Hasama

Kenji Kintaka

Keisuke Sorimoto

Hiroshi Takahashi

Shojiro Kawakami

Takayuki Kawashima

Toshikazu Ijiro

Takafumi Chiba

Mitsuhiro Yasumoto

Toshiharu Saiki

To provide a volume-type optical element in which a self-cloning photonic crystal is used. An optical element is provided with half-wave plates of photonic crystals formed on the xy plane and laminated in the z-axis direction in a three-dimensional space x, y, z. The groove direction of the photonic crystals is a curved line, and the angle in relation to the y-axis direction changes continuously in the range of 0&#xb0;-180&#xb0;. Light entering the optical element in the axial direction is emitted from the optical element upon being divided and converted into clockwise circularly polarized light in the direction facing the x-axis by a given angle from the z-axis and anticlockwise circularly polarized light in the direction facing the &#x2212;x-axis by a given angle from the z-axis. Laminating or placing a quarter-wave plate comprising a photonic crystal on one or both surfaces makes it possible to divide light entering from the z-axis direction of the optical element into two orthogonal linearly polarized lights.

Optical element

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

It is an object of the present invention to provide a multimode interference waveguide type optical switch that has a wide tolerance and that digitally performs switching with respect to a change in an applied voltage or injected current. The multimode interference waveguide type optical switch of the present invention includes an input single-mode waveguide () into which input light is entered, a multimode rectangular slab waveguide () into which light emitted from the input single-mode waveguide is entered, two electrodes () that are arranged in parallel in a waveguide direction on the slab waveguide and that decrease the refractive index of the slab waveguide () disposed thereunder by injecting current or applying voltage, and a plurality of output single-mode waveguides () into which light emitted from the slab waveguide () is entered and from which output light is emitted.

Multimode interference waveguide type optical switch

An optical functional waveguide having a small size, used with stored energy, controlling the phase of light at high speed, and adjusting the optical path length. The optical functional waveguide includes a substrate (), a quartz waveguide clad (), a quartz waveguide core (), groove structures (), a filling material (), and heater electrode (). The filling material () placed in the groove structures () is, e.g., a resin transparent to the wavelength region of the guided light, and the refractive index temperature coefficient is about 10 to 100 times that of quartz. The heater electrode () is interposed between the groove structures () provided along the optical path. Therefore, the temperature of the filling material () can be varied sharply and quickly with little energy expended.

Optical functional waveguide, optical modulator, arrayed waveguide grating, and dispersion compensation circuit

A diffraction grating of the present invention includes a first block () and a second block (). The first block () is made up of a plurality of input waveguides (), a slab waveguide (), a delay waveguide array () and narrow grooves (): each of which being filled with resin. The second block () is made up of a plurality of input waveguides (), a slab waveguide () and a plurality of output waveguides (). Since a circuit is cut off at the ends of the arrayed waveguides, a relative phase can easily be measured. The resin has undergone a refractive-index adjustment and compensates a phase error.

Diffraction grating and dispersion compensation circuit

In order to provide a low-loss optical switch that is low in power consumption by providing the same as a self-holding type, and high speed and highly practicable, an optical switch of the present invention is composed of a quartz substrate (), first and second input waveguides (and), a first directional coupler (), first and second arm waveguides (and) of a Mach-Zehnder interferometric circuit, a second directional coupler (), first and second output waveguides (and), and a phase change material portion (). A control light (for an amorphous to crystal transition) pulse (pulse width: 20 ns, pulse intensity: 5 mW) having a wavelength of 0.78 microns is irradiated. As a result of the control light pulse irradiation, the phase change material portion () changes in phase to a crystal state, and the optical switch transits to a bar condition.

Growing community of inventors

Yokohama, Japan

Hiroyuki Tsuda