Hitachi Cable, Inc.

National Institute of Advanced Industrial Science and Technology

Keio University

Other

Hitachi, Ltd.

Sharp Kabushiki Kaisha Corporation

Nippon Telegraph and Telephone Corporation

Agency of Industrial Science and Technology

National Institute of Advanced Industrial Science

Steravision Co., Ltd.

Hisato Uetsuka

Hideaki Arai

Takafumi Chiba

Koichi Maru

Masahiko Mori

Hiroshi Ishikawa

Hiroyuki Tsuda

Hitoshi Kawashima

Ryoji Suzuki

Toshifumi Hasama

Masahiro Okawa

Korenori Tamura

Tatsuo Teraoka

Hiroaki Okano

Dai Kobayashi

Kenji Kintaka

Keisuke Sorimoto

Satoshi Aoki

Shu Yamamoto

Masahiro Yanagisawa

Yukio Kurata

Masaru Miyazaki

Katsuyuki Imoto

Hirohisa Sano

Yasufumi Yamada

Tetsuya Miyazaki

Shalini Venkatesh

Kohji Minami

Marshall Thomas DePue

Kazuhiro Ikeda

Hirobumi Ouchi

Yoshinobu Mitsuhashi

Kenji Akiba

Shu Namiki

Yasunori Iwafuji

Yoshimasa Fujii

Hideki Nounen

Satoshi Takasugi

Keiichi Higuchi

Naoyuki Matsuoka

Masahiro Ookawa

Tetsu Hasegawa

Bing Yao

Masahiro Hikage

In the prior art, a scanning element used for Lidar in the self-driving car technology employed a mirror or the like continuously rotated by MEMS, and due to the inertia of the mirror or the like, the scanning element was suited for a raster scan that scans a scene in one stroke, but was incapable of discontinuous movement from one arbitrary point to another, and programmable scanning with an arbitrary frequency in an arbitrary pattern, as fast as the raster scan. In the present invention, there was fabricated Lidar, which is composed of a polarization diversity scheme and a scanning element, wherein the polarization diversity scheme uses two polarization gratings, each polarization grating having a thickness such that it becomes a half-wave plate, wherein birefringent directors of each polarization grating rotate with a period &#x39b;, wherein these polarization gratings are disposed with a desired interval from each other, wherein a half-wave plate is inserted in either one of two paths of separated, exiting right-handed or left-handed circularly polarized light beam, depending on a rotation direction of the circularly polarized light, to thereby enable conversion of light beams into parallel proximate circularly polarized light beams with the same rotational direction, and wherein the scanning element has a multistage structure of polarization switch-polarization grating sets connected in combination, with a polarization switch and a polarization grating being defined as one set.

Circular polarization-type polarization diversity element, scanning element using same, and lidar

[Problem] Conventional multi-stage optical switching elements have had the problems that, when the number of polarized light beams becomes large, walkoff of light beams produced in middle stages is gradually amplified so that beams at the terminal end deviate from the opening surface and the configuration of the optical switching element itself becomes larger. [Solution] Developed is a 1&#xd7;N light beam switching element, which has a cube-type modular structure comprising a corner cube and a cubical cube with roughly identical dimensions, which is one-dimensional, two-dimensional, and three-dimensional, and which is fast, highly efficient, wide-angled, and compact, by combining: a simple corner-cube reflection-type light beam switching element comprising a polymer-stabilized blue-phase liquid crystal layer sandwiched between two transparent electrodes in the form of parallel plates, a mirror, and a wedge-shaped prism; and a walkoff correction element in which a condensing-type polarization grating is arranged or affixed to a cubical.

Light beam switching element, assembly of same, and control method for same

When polymer-stabilized blue-phase liquid crystal is driven by comb-shaped electrodes, a large electric field is generated near the electrodes, and electrostriction results in degradations in the switching speed of polymer-stabilized blue-phase liquid crystal. This optical switching engine is manufactured by inserting polymer-stabilized blue-phase liquid crystal between parallel plates on which are formed conventional thin film electrodes, followed by bonding a polarization grating plate thereto, and disposing or bonding two silicon wedges having triangular cross sections to the sides thereof so as to have rotational symmetry with each other.

High-speed optical switching engine

With the conventional optical deflection elements using polarization gratings (PGs), it has been difficult to independently switch multiple optical beams at one time in a variety of angular ranges and angular steps at high speed on the &#x3bc;-second time scale, and it has been impossible to achieve a highly reliable optical deflection element module capable of operating at different ambient temperatures. Provided is an optical deflection element including: a polarization grating plate having a rectangular or circular segment structure, in which the cycles &#x39b; of PGs are not uniform within the plate plane and the cycle and/or the rotational direction of a birefringence axis varies; and a phase panel having a segment structure that is accordingly segmented within the same plane are bonded together, wherein their corresponding segments overlap with each other, and optical switches of the polarization gratings are controlled by a voltage change in the phase panel.

Optical beam deflection element and module

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 waveguide type wavelength domain optical switch includes an input/output port including at least three waveguide spectrometers stacked in thickness direction, a first lens for collecting light outputted from an input port of the input/output port in one axis direction, a second lens for collecting light outputted from the first lens in a direction orthogonal to the collecting direction of the first lens, and an optical phase modulation cell for reflecting light outputted from the second lens through the second lens and the first lens to an output port of the input/output port. Alternatively, the input/output port may include at least two waveguide spectrometers and a waveguide optical coupler circuit stacked in thickness direction.

Waveguide type wavelength domain optical switch

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

A waveguide type variable optical attenuator has: a substrate; two optical circuits that are in parallel formed on the substrate, each of the optical circuits including two couplers that conduct the branching and coupling of light and are connected to the input port and output port of light and two waveguides through which the two couplers are connected; a polarization maintaining fiber one end of which is connected to the output port of one of the two optical circuits and the other end of which is connected to the input port of the other of the two optical circuits while being twisted 90&#xb0;; and a heater that is provided around neighboring waveguides of the two optical circuits such that the neighboring waveguides share heat to be generated by the heater.

Waveguide type variable optical attenuator

A waveguide-type optical multiplexer/demultiplexer with low crosstalk characteristics and reduced wavelength dispersion is provided. A waveguide-type optical multiplexer/demultiplexer comprising, first, second and third optical multiplexer/demultiplexer circuits connected in multistage, each multiplexer/demultiplexer circuit has four input-output ports, third input-output port of first optical multiplexer/demultiplexer circuit is connected to third input-output port of second optical multiplexer/demultiplexer circuit, and fourth input-output port of first optical multiplexer/demultiplexer circuit is connected to fourth input-output port of third optical multiplexer/demultiplexer circuit, when wavelength division multiplex signals having wavelength &#x3bb;, &#x3bb;, &#x3bb;, &#x3bb;, &#x3bb;, &#x3bb;. . . are input through first input-output port of first optical multiplexer/demultiplexer circuit, multiplex signals of odd wavelength &#x3bb;, &#x3bb;, &#x3bb;. . . are output from first input-output port of second optical multiplexer/demultiplexer circuit, and multiplex signals of even wavelength &#x3bb;, &#x3bb;, &#x3bb;. . . are output from first input-output port of third optical multiplexer/demultiplexer circuit.

Waveguide-type optical multiplexer/demultiplexer

In an optical multiplexer/demultiplexer comprising optical multiplexer/demultiplexer circuits connected in multistage, the optical multiplexer/demultiplexer circuits each have two input ports and two output ports, an optical path, through which input optical signals with predetermined wavelengths are output after multiplexing and demultiplexing, varies depending upon the input port; the optical paths in each of the optical multiplexer/demultiplexer circuits have mutually opposite wavelength dispersion characteristics, and one of the optical paths in a first optical multiplexer/demultiplexer circuit is connected to one of the optical paths, in a second optical multiplexer/demultiplexer circuit, having wavelength dispersion characteristics opposite to the optical path in the first optical multiplexer/demultiplexer circuit. By virtue of this construction, an optical multiplexer/demultiplexer can be realized which causes no significant wavelength dispersion and, at the same time, has excellent wavelength flatness characteristics in passband.

Optical multiplexer/demultiplexer

An optical switching apparatus and a method of efficiently switching optical signals are disclosed. Optical insertion loss may be reduced in a planar lightwave circuit by determining an optimal spacing between perturbations including using passive perturbations, having a three dimensional refractive index distribution, in an array of waveguides, or by adjusting parameters of existing perturbations e.g. their spacing. The perturbation and each waveguide have different three dimensional refractive index distributions. The perturbation may be positioned anywhere in the array of waveguides. The perturbation may be a trench, a region of refractive index different from that in each waveguide, a broken waveguide core, or a modification of the topography of the array of waveguides. In one embodiment, the perturbation is a periodic or quasiperiodic perturbation.

Method and apparatus for reducing optical insertion loss in planar lightwave circuits through dielectric perturbation optimization

In the optical multiplexer/demultiplexer according to the invention, an MMI (multi mode interference) coupler having a percentage coupling of about 50% is used as first and second optical couplers, and a directional coupler having a percentage coupling of less than 10% is used as third and fourth optical couplers. By virtue of this constitution, the optical multiplexer/demultiplexer according to the invention has a small dependency upon wavelength and can be used in a wide waveband, is less susceptible to a preparation error, and, at the same time, has good wavelength flatness in passband and a wide rejection band.

The present invention relates to an array waveguide grating and a method of manufacture thereof, in which a substantially smooth wavelength-loss characteristics is obtained in a pass band, rather than increasing the loss. In an array waveguide grating ( ), wavelength multiplex division signal light is demultiplexed by a channel waveguide array ( ), reflected by a Fabry-Perot resonator array ( ), and passed through the channel waveguide array ( ) again, so that a substantially smooth wavelength-loss characteristic is obtained in the pass band, rather than increasing the loss.

Array waveguide grating and method of manufacture thereof

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Hitachi, Japan

Hisato Uetsuka