Nippon Telegraph and Telephone Corporation

Nippon Telephone and Telegraph Corporation

Nippon Telegraph and Telephone Communications

Tadayuki Imai

Kazuo Fujiura

Masahiro Sasaura

Seiji Toyoda

Shogo Yagi

Takashi Kurihara

Koji Enbutsu

Jun Miyazu

Makoto Shimokozono

Akiyuki Tate

Makoto Abe

Masahiro Ueno

Sohan Kawamura

Haruki Kozawaguchi

Eishi Kubota

Kouichirou Nakamura

Touru Matsuura

Hiroshi Fushimi

Soichi Oka

Hiroki Yamazaki

Yuichi Akage

Michio Ono

Shougo Yagi

Takashi Sakamoto

Tohru Matsuura

Takashi Kobayashi

Hiroshi Yoshikawa

Kazuhito Higuchi

Saburo Imamura

Satoru Tomaru

Masahiro Endo

Kazunori Naganuma

Yuichi Okabe

Kazuto Noguchi

Noboru Sonehara

Tsutomu Horikoshi

Makoto Hikita

Tetsuyoshi Ishii

Takaaki Akimoto

Kazutoshi Kato

Yoshiaki Kurokawa

Shigeo Ishibashi

Haruhiko Kojima

Akinori Furuya

Hiroki Kohda

The present invention includes an optical deflector that changes a deflection angle depending on an applied voltage, a voltage control unit that applies a voltage to the optical deflector, and a storage unit that stores a value of a voltage to be output by the voltage control unit. The voltage control unit outputs a voltage of a value stored in the storage unit to the optical deflector. The storage unit stores a goal voltage V=g(t), which provides a deflection angle θ with the goal time dependency θ=θ(t).

Control method of optical deflector, and optical deflection device

On an optical path of a condensing lens (), a varifocal lens () is disposed. The varifocal lens () is formed of an electro-optic crystal such as, e.g., potassium tantalate niobate. A condensation position measurement unit () measures a condensation position where laser light is condensed by the condensing lens (). A condensation position control unit () controls a focal position of the varifocal lens () such that a difference between the condensation position measured by the condensation position measurement unit () and a prescribed condensation position that has been set falls within an acceptable range.

Laser processing device

An optical deflector includes an electro-optical material in a paraelectric phase and having a trap for accumulating charges inside the electro-optical material; an electrode pair formed on facing surfaces of the electro-optical material; a first and second conductor hold units provided so as to hold the electro-optical material and the electrode pair therebetween; a temperature sensor that measures at least one of temperatures of the conductor hold units; and a temperature control unit that controls the temperatures of the conductor hold units, based on the measurement temperature, and the optical deflector sets an optical axis of incident light into the electro-optical material so as to be orthogonal to the electric field direction, applies between the electrode pair an alternating current voltage on which a direct current bias voltage is superimposed, and thereby deflects the incident light, in which the temperatures of the first and second conductor hold units are controlled so as to give the electro-optical material a temperature gradient to make a charge density in the electro-optical material substantially uniform.

Light deflector

A wavelength swept light source includes a sawtooth waveform as a main waveform and an exponential component of the sawtooth waveform to the controlled voltage of the electro-optic deflector. The controlled voltage is controlled so that, as an oscillation wavelength to be swept is swept towards a longer wavelength side, a change rate of the oscillation wavelength is increased.

Wavelength swept light source

A variable focusing lens is provided that can change the focal length at a high speed. The variable focusing lens includes: a single crystal electrooptic material having inversion symmetry; a first anode formed on a first surface of the electrooptic material; a second cathode provided to have an interval to the first anode; and a first cathode and a second anode that are formed on a second surface opposed to the first surface and that are formed at positions opposed to the first anode and the second cathode. An optical axis is set so that, when light enters through a third face orthogonal to the first surface, light exists through a fourth surface opposed to the third face. A voltage applied between the first and the second pair of electrodes is changed to thereby change the focal point of light emitted from the fourth surface of the electrooptic material.

Variable focusing lens and microscope

An electrooptic device having a simple structure that can efficiently increase deflection of a beam is provided. The device includes: an electrooptic crystal () having an electrooptic effect; an electrode pair of a positive electrode () and a negative electrode () for generating an electric field inside the electrooptic crystal; and a power source for applying a voltage between the electrode pair so as to generate a space charge inside the electrooptic crystal. With this arrangement, by using a simple structure, a change in a deflection angle is temporally rapid, and a large deflection angle that cannot be obtained by a conventional electrooptic crystal prism can be acquired at a low applied voltage.

Electrooptic device

To provide a variable-focal length lens capable of altering its focal length at high speed. The variable-focal length lens has an electrooptic material and electrodes formed on an incident surface of light and on an exit surface of the light of the electrooptic material. An optical axis is set so that the light is inputted into a gap where the electrodes of the incident surface are not formed and is outputted from a gap where the electrodes of the exit surface are not formed. A focus of the light that is transmitted through the electrooptic material becomes variable by varying an applied voltage between the electrodes of the incident surface and the electrodes of the exit surface.

Variable-focal length lens

An electrooptic device having a simple structure that can efficiently increase deflection of a beam is provided. The device includes: an electrooptic crystal () having an electrooptic effect; an electrode pair of a positive electrode () and a negative electrode () for generating an electric field inside the electrooptic crystal; and a power source for applying a voltage between the electrode pair so as to generate a space charge inside the electrooptic crystal. With this arrangement, by using a simple structure, a change in a deflection angle is temporally rapid, and a large deflection angle that can not be obtained by a conventional electrooptic crystal prism can be acquired at a low applied voltage.

An optical medium having a high refractive index without anisotropy and a wide transmission wavelength is obtained. The cubic crystal material is &#x3b1;&#x3b2;O, where &#x3b1; is at least one of K, Ba, Sr, Ca, and &#x3b2; is at least one of Ta, Ti. Optimally, the cubic crystal material is KTaNbO, where composition x is 0&#x2266;x&#x2266;0.35. This composition enables to raise refractive index while its phase transition temperature is below a room temperature.

Optical medium, an optical lens and a prism

A method and an apparatus for producing crystals wherein crystal quality can be kept and a crystal composition is uniformed from a growth early stage to a growth last stage are provided. In an apparatus for producing crystals wherein the crystalsare grown from a liquefying raw materialin a crucible retained in a furnace and slowly cooling the raw materialin the cruciblefrom below upward, the apparatus comprises a raw material supply apparatuswhich supplies a resupply raw material, and a reflection plateplaced above the crucible, which liquefies the resupply raw materialsupplied from the raw material supply apparatusand drops it as a liquid into the crucible.

Method and apparatus for producing crystals

An inexpensive multi-layered holographic read-only memory having a large capacity is provided. In the memory in which single-mode slab waveguides are multi-layered, a periodic scattering center whose period approximately agrees with the period of the guided mode is provided in at least one of a core layer and a clad layer in each waveguide so that a guided wave in the waveguide is diffracted by the periodic scattering center to the outside of the waveguide and a holographic image is generated.

Multi-layered holographic read-only memory and data retrieval method

An optical memory medium () has cores () each constituting a planar optical waveguide and clads () sandwiching each core, and has a data image () in which data is recorded as a scattering factor and a pair of positioning marks () which are scattering factors required for positioning at an interface between a core () and a clad () or in the core (). A read light () travels while spreading in the core () and scatters and interferes by the data image (), and data is reproduced from a data reproduction light () generated by this scattering and interference. A pair of positioning lights () are caused to enter the core () with offsets with respect to the read light () in opposite directions along a thickness direction of the core (), and scatter and interfere at the pair of positioning marks (). Incidence positions of the lights emitted from a light source () with respect to the core () in a thickness direction of the core () are controlled based on intensities of a pair of positioning mark lights () generated by this scattering and interference.

Optical memory reproduction apparatus and incidence positioning method for read light thereof

The present invention provides an optical switch, an optical modulator, and a wavelength variable filter each of which has a simple configuration, which requires only a low driving voltage, which is independent of polarization, and which can operate at high speed. An optical switch according to the present invention includes a 3-dB coupler () placed on an input, a 3-dB coupler () placed on an output, and two optical waveguides connecting the input-side 3-dB coupler and the output-side 3-dB coupler together. The optical switch also includes a phase modulating section () that applies electric fields to one or both of the two optical waveguides. At least two optical waveguides are a crystal material including KTaNbO(0&#x3c;x&#x3c;1) and KLiTaNbO(0&#x3c;x&#x3c;1, 0&#x3c;y&#x3c;1), or KTaNbOor KLiTaNbO.

Optical switch, optical modulator and wavelength variable filter

Growing community of inventors

Atsugi, Japan

Tadayuki Imai