Nippon Telegraph and Telephone Corporation

The Furukawa Electric Co., Ltd.

Sumitomo Electric Industries, Limited

Kunihiko Mori

Hidehiko Takara

Satoki Kawanishi

Masatoshi Saruwatari

Atsushi Takada

Wataru Imajuku

Toshio Morioka

Takeshi Yagi

Masayuki Nishimura

Masashi Onishi

Toshiaki Okuno

Isamu Kobayashi

Shinichi Arai

Takuya Ohara

Tetsuro Inui

Yoshitada Katagiri

Atsushi Higashiura

Naoyuki Chida

Kenji Sato

Kohichi Robert Tamura

A mode-locked laser serves as a light source for stabilizing the frequency of each optical carrier and generates high-quality optical multi-carrier. The mode-locked laser is equipped with a master laser for generating master laser light; a mode-locked laser section including in an optical resonator at least a modulating section, am amplifying section, and a bandwidth limiting section for reducing mode partition noise; and a signal generating section for generating a periodic signal that serves for mode locking of the mode-locked laser section and is to be applied to the modulating section. The master laser light is input to the optical resonator of the mode-locked laser section to cause injection locking. An optical multi-carrier source is constructed by combining this mode-locked laser with a waveguided optical nonlinear medium.

Mode-locked laser and optical multi-carrier source using same

An optical parametric circuit including an optical coupler including a first output port and a second output port, and a nonlinear loop mirror on which an optical path which connects the first output port and the second output port is formed, in which the nonlinear loop mirror includes an optical dispersive medium and a second-order optical nonlinear medium through which the optical path passes, and in which an order of placement of the optical dispersive medium and the second-order optical nonlinear medium on the optical path in one direction from the first output port to the second output port is the reverse of an order of placement of the optical dispersive medium and the second-order optical nonlinear medium on the optical path in another direction from the second output port to the first output port.

Optical parametric circuit

A chirp measurement apparatus includes a splitting section for splitting input signal light to two paths; a first dispersion medium with a total dispersion amount of +D (&#x2260;0) at a used wavelength, and a second dispersion medium with a total dispersion amount of &#x2212;D (&#x2260;0) at the used wavelength; first and second nonlinear photo-detecting sections for receiving the signal light beams passing through the first and second dispersion media, and for outputting electric signals with the intensities proportional to nth power of the intensities of the signal light beams, where n is greater than one; and a difference detecting section for computing a difference between the electric signals output from the first and second nonlinear photo-detecting sections, and for outputting a differential signal corresponding to the difference as a chirp signal of the input signal light.

Chirp measurement apparatus

An optical parametric circuit for separating an input signal light and a wavelength-converted light even when the wavelength difference is small is provided. The optical parametric circuit includes: a nonlinear Mach-Zehnder interferometer which includes a first optical path and a second optical path; optical dispersive mediums and second-order optical nonlinear mediums provided in the first and second optical paths; wherein optical dispersive medium and second-order optical nonlinear medium in the first optical path are placed in the reverse order of optical dispersive medium and second-order optical nonlinear medium in the second optical path.

An optical fiber, capable of generating by means of nonlinear phenomena, white light in adequately broadened wavelength bands at both sides of a pumping optical pulse that is input, and stabilizing the polarized conditions. The fiber is formed by covering a core with a first cladding, and covering the first cladding with a second cladding, where the second cladding has a refractive index greater than that of the first cladding, but lower than that of the core. Stress-applying parts are provided inside the second cladding so as to sandwich the core from both sides to form a polarization-maintaining optical fiber. The shortest distance between the stress-applying parts is made 2.3 times or more the mode field diameter for the wavelength of the pumping optical pulse.

Optical fiber

A method for manufacturing an optical filter capable of manufacturing an optical filter in such a manner that the transmission wavelength varies linearly with respect to the angle &thgr; in the rotation direction of the substrate and that almost the entire range of the angle &thgr; is utilizable as the optical filter. A mask capable of being rotated relatively with respect to the substrate coaxially on a plane parallel to the substrate, which is either having an aperture extending along a radius direction with an aperture angle &phgr; or itself extending along a radius direction to cover an angle &phgr;, is provided over the substrate. Then, the mask is relatively rotated with respect to the substrate at least once at a non-constant angular speed during a formation of a single layer or multiple layers on the substrate, while depositing a dielectric material in a single layer or multiple layers on the substrate from the mask side within a deposition chamber.

Method for manufacturing optical filter

A multilayer insulated wire has two or more extrusion-coating insulating layers provided on a conductor directly or via some other layer, or provided on the outside of a multicore wire composed of conductor cores or insulated cores that are collected together, wherein at least one of the insulating layers is made of a mixture prepared by mixing 100 parts by weight of a polyethersulfone resin and 10 to 100 parts by weight of an inorganic filler. A transformer utilizes the multilayer insulated wire. The multilayer insulated wire can realize such high heat resistance as heat resistance F class (155&deg; C.), which satisfies IEC 950 standards, or higher heat resistance, in transformers; and can exhibit excellent electrical properties even at high frequencies. Further, when the transformer is used at high frequencies, the electric properties are not lowered, and influence by the generation of heat can be prevented.

Multilayer insulated wire and transformer using the same

The present invention relates to a white pulse source that produces spectrally shaped white pulses of a constant optical output power over a wide wavelength range. The white pulse source includes a pump pulse source for generating pump pulses with a center wavelength .lambda.0 and a waveguided nonlinear optical medium with a length L. The waveguided nonlinear optical medium is characterized by two properties: the first property is that chromatic dispersion D(.lambda.0,z) at the center wavelength of pump pulses in ps/nm/km is positive at an input end of said waveguided nonlinear optical medium, where z=0, and decreases towards an output end. The second property is that said chromatic dispersion D(.lambda., z) has a maximum value D(.lambda.p(z), z) at a peak wavelength .lambda.p(z) within a range of propagation distance given by L1.ltoreq.z.ltoreq.L where 0.ltoreq.L1&lt;L, and that said chromatic dispersion D(.lambda., z) has two zero-dispersion wavelengths, .lambda.1(z) and .lambda.2(z), where D(.lambda.1(z), z)=D(.lambda.2(z), z)=0 ps/nm/km, within a range of propagation distance z where D(.lambda.p(z), z) shows a positive value.

White optical pulse source and applications

High peak pulse light is incident on an optical fiber having a dispersion decreasing region which serves as a main region for generating supercontinuum or idler light and in which the chromatic dispersion does not increase but at least partially decreases in the direction in which light travels. The fiber can be applied to broad band width idler light generation with both light transmission directions. Four wave mixing upon incidence of the light on the dispersion decreasing region of the optical fiber are efficiently obtained.

Optical fiber and light source apparatus

A coherent white light source generates a uniform and continuous coherent white light spectra over 200 nm at a low pump power. The source is based on a pump light source which produces pump optical pulses at a wavelength .lambda..sub.0 and an optical waveguide to receive a pump optical pulse at .lambda..sub.0 to generate a white pulse having a wavelength spread of .DELTA..lambda.. The optical waveguide is characterized by having dispersion properties such that four-wave mixing light having a wavelength spread of .lambda..sub.0 .+-..DELTA..lambda./2 is produced, and the power gain of the four-wave mixing light is greater than 1. These properties of the waveguide are defined by: the path length of the waveguide device ln G.sub.0 /(2.vertline..gamma..vertline.P) in units of �km!, an absolute value of the dispersion slope to be not more than 16(.vertline..gamma..vertline.E)(.DELTA..lambda..sup. ln G.sub.0) in units of �ps/nm.sup.2 /km! and an absolute value of the dispersion at the wavelength .lambda..sub.0 to be not more than (16/.pi.c) .lambda..sub.0.sup.2 .vertline..gamma..vertline.P/(.DELTA..lambda.).sup.2 in units of �ps/nm/km!. Examples of optical devices utilizing such a super-wideband coherent white light source are demonstrated.

Coherent white light source and optical devices therewith

The present invention provides an optical parametric circuit for separating four-wave-mixing wave(s) (FWM wave(s)) from signal wave(s) and/or pump waves without using a wavelength filtering device, and optical circuits using the same. The optical parametric circuit of the present invention is made by connecting two output ports of a 2.times.2 optical directional coupler to a nonlinear optical medium via dispersive optical media, each of which has a specific length and a specific propagation constant. By inputting signal waves having carrier angular frequencies .omega..sub.Sj (j=1, 2, . . . N) and pump waves having carrier angular frequencies .omega..sub.P1, .omega..sub.P2 into the first input port of the optical directional coupler, the FWM waves, generated in the nonlinear optical medium, having carrier angular frequencies .omega..sub.fj (=.omega..sub.P1 +.omega..sub.P2 -.omega..sub.S) are output from the second input port of the optical directional coupler. By inputting the signal waves and the pump waves from different input ports of the directional coupler, it is possible to separate amplified signal waves and the FWM waves from the pump waves. By adjusting the lengths and the propagation constants of the dispersive optical media, the amplified signal waves are separated from the pump waves and the FWM wave. The optical parametric circuit is used for wavelength conversion of optical signals, parametric amplification of optical signals, optical phase conjugation (spectral inversion) and for all-optical switching and for optical circuits using the same, for example, optical logic circuits, optical time-division multi/demultiplexers and/or optical sampling circuits.

Growing community of inventors

Yokosuka, Japan

Kunihiko Mori