Photonic Lattice, Inc.

Autocloning Technology Ltd.

Hitachi, Ltd.

Japan Science and Technology Agency

Hitachi Cable, Inc.

Tokyo Electric Co.

Keio University

Sophia School Corporation

Sumitomo Special Metal Co. Ltd.

Shojiro Kawakami

Takayuki Kawashima

Takashi Sato

Toshikazu Ijiro

Kazuo Shiraishi

Takafumi Chiba

Hiroshi Takahashi

Tsuneo Suganuma

Toshiki P Tanaka

Sachio Toyota

Seiichi Onoda

Hiroyuki Tsuda

Shigeo Nishida

Masao Sumi

Makoto Minakata

Yoshihiro Sasaki

Wataru Ishikawa

Mitsuhiro Takata

Yasuo Otera

Hiroyuki Sakaki

Kazutaka Baba

Naoki Hashimoto

Seiji Hattori

An optical element has a quarter-wave plate formed on the X-Y plane and laminated in the Z-axis direction in three-dimensional space X, Y, Z. The groove in the wave plate is curved, and the angle relative to the Y-axis varies continuously in the range of 0&#xb0; to 180&#xb0;. The optical element separates and converts incoming circularly polarized light into light passing therethrough and circularly polarized light reversely rotating a given angle toward the X axis from the Z axis, and outputs the light.

Optical element and optical circuit

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

A small and high-speed polarization analysis device and ellipsometer having no driving section are provided by overlapping one polarizer array rendered by arranging a plurality of polarizer regions of mutually different optical axis directions in the form of stripes and one wavelength plate array rendered by arranging a plurality of wavelength plate regions of fixed retardation and mutually different optical axis directions in the form of stripes so that the respective stripes of the plurality of polarizer regions and of the plurality of wavelength plate regions intersect one another and by disposing a light-receiving element array so that the intensities of light that has passed through the matrix-like intersection parts can be individually measured. As a method of analyzing a two-dimensional intensity distribution pattern that is observed by the light-receiving element array of the polarization analysis device, either one of (or both of) the algorithms of a method that determines incident polarized waves by mathematically fitting pattern shapes or performing database matching or a method that performs a Fourier transform on pattern shapes and determines incident polarized waves from the frequency components is (are) used. Furthermore, if necessary, more accurate polarization analysis is also possible by adopting a signal processing method that removes signals from light-receiving element regions that receive unnecessary scattered light and diffracted light.

Driverless ellipsometer and ellipsometry

A thin polarizer array and a wavelength plate array that are composed of micro regions having different optical axis directions and wavelength characteristics and having a high extinction ratio and a low insertion loss, and a polarization analyzer using them. An array of micro periodic grooves is formed on a substrate, with the directions changed from one region to another. An alternating multilayer film formed by bias sputtering alternating a layer of high refractive index material such as Si or TaOand a layer of low refractive index material such as SiO. By selecting a condition that each layer maintains its periodic projecting/recessed shape, an array of photonic crystal polarizer is formed. By mounting this array of photonic crystal polarizer in a photodetector array, a polarization analyzer that is small, has no movable part, has a small number of components, and enables high-precision measurement is constituted.

Polarization analyzer

A polarizer which has and regularly arranged two-dimensional structure which has a pitch of 1 mm or so or less. The polarizer has structure in which two or more film-shaped materials which have a substantially regularly arranged one-dimensional undulation. The polarizer also has a substantially regularly arranged two-dimensional structure. For example, the polarizer consist of materialsandwhich have different refractive indexes. A regularly arranged two-dimensional structure which has a pitch of 1 mm or less can be obtained by a simple method. Because of this structure, the polarizer transmits the incident light which has a specific polarized plane and reflects the incident light which has a polarized plane which is orthogonal to the plane.

Polarizer

A three-dimensional periodical structure whose period is about 1 &#x3bc;m or smaller is provided. At least two kinds of films which have two-dimensionally substantially periodical projections are successively formed in layers substantially periodical to construct structure which is substantially three-dimensionally periodical. For instance, the films are made of materials different in refractive index. The three-dimensional periodical structure whose period is about 1 &#x3bc;m or smaller can be obtained by a simple fabricating method. By this structure, the propagation of a wave with a specific wavelength in many solid angular directions including several axial directions parallel to the plane and the thickness direction of the layers can be cut off.

Three-dimensional periodical structure, its manufacturing method, and method of manufacturing film

A method of manufacturing an optical isolator which has a rotator capable of rotating a plane of polarization by the Faraday effect, and a polarizer of multilayer structure formed of alternately superposed transparent dielectric films and films having a complex dielectric constant, includes the steps of: forming the rotator as a plate having a large area and the polarizer as an array having a large area; forming an optical isolator array by attaching the polarizer array at least to one surface of the rotator plate in such a manner that the layers of the polarizer array extend perpendicularly to the surface of the rotator plate; and cutting the optical isolator array into a plurality of optical isolator chips. An optical module incorporating the isolator chip includes a case, a semiconductor laser provided in the case, an optical fiber fixed to the case with the optical axis thereof in alignment with that of the semiconductor laser, and the optical isolator chip attached directly or through a transparent member to the end of the optical fiber. The structure enables the optical module to be assembled easily and accurately, and to be of a compact lightweight construction.

Optical isolator

There is disclosed an optical switch comprising an optical fiber, a block of PLZT, and two polarizers disposed on opposite sides of the block. The fiber has one or more grooves in which the block and the polarizers are received. The block of PLZT induces an electric field perpendicular to the axis of the core of the fiber. The groove or grooves extend across the core of the fiber such that the block covers the whole cross section of the core. Each polarizer consists of alternate laminations of a metal and a dielectric. The laminations are stacked in a direction perpendicular to the axis of the core. Each dielectric lamination is thicker than each metal lamination. If incident light is polarized, one of the polarizers is omitted.

Optical switch

A three-layer structure optical fiber comprises a first transparent dielectric core layer having a relatively high refractive index, a second transparent dielectric intermediate layer having a relatively low refractive index and a third transparent dielectric cladding layer having an intermediate refractive index wherein the parameter of the optical fiber is determined as follows: ##EQU1## where B is the bandwidth of the signal to be transmitted, z is the transmission distance, C is the velocity of light in vacuum, .eta.o is the refractive index of the core layer, q is the ratio of refractive indices between the core layer and second layer, V = normalized frequency, ##EQU2## p is the ratio of refractive index between the core layer and the third layer, and U.sub.11 =2,405.

Optical fiber

Growing community of inventors

Sendai, Japan

Shojiro Kawakami