Nippon Telegraph and Telephone Corporation

Ntt Advanced Technology Corporation

Nippon Telegraph and Telephone Communications

Kazunori Naganuma

Yuichi Okabe

Shoichi Sudo

Takuro Tajima

Katsunari Okamoto

Shogo Yagi

Takashi Kurokawa

Tetsuyoshi Ishii

Hirokazu Takenouchi

Shigeo Ishibashi

Hiroyuki Tsuda

Takeshi Watanabe

Takashi Sakamoto

Masahiro Ueno

Tadayuki Imai

Seiji Toyoda

Juichi Noda

Kazuto Noguchi

Jun Miyazu

Kazutoshi Kato

Itaru Yokohama

Yuzo Ishida

Eiichi Sugai

Hiizu Takemura

Noriyuki Ishidu

Hideki Hagino

Akira Sawaguchi

Tohru Kodaira

Fumio Saito

Provided is a position locating instrument for a position locating method in which position locating instruments that transmit and receive light beams are arranged in series connection. The position locating instruments reduce error factors and improve measurement accuracy by providing all or some of necessary position and attitude parameters. The position locating instrument has at least one light emission port through which light from a wavelength-changeable light source is emitted; and at least one light receiving port that receives light emitted or reflected by an adjacent position locating instrument. The light emitted from the light emission port has a fanlike pattern and has an emission angle varying, as a monotonic function of a wavelength of the light, in a direction perpendicular to a direction in which the light spreads in the fanlike pattern.

Position locating instrument

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

An object of the present invention is to provide a noninvasive constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method, in which accurate measurement can be performed by superimposing two photoacoustic signals having the same frequency and reverse phases to nullify the effect from the other constituent occupying large part of the object to be measured. The constituent concentration measuring apparatus according to the invention includes light generating means for generating two light beams having different wavelengths, modulation means for electrically intensity-modulating each of the two light beams having different wavelengths using signals having the same frequency and reverse phases, light outgoing means for outputting the two intensity-modulated light beams having different wavelengths toward a test subject, and acoustic wave detection means for detecting an acoustic wave generated in the test subject by the outputted light.

Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method

A method for measuring a temporal waveform of the electric field of an optical signal avoids substantial sacrifice of sensitivity and enables accurate measuring of the ultra-fast temporal waveform of the electric field of the optical signal. It generates phase conjugated light by applying light whose phase is fixed with respect to optical signal to be measured; obtains spectral phase by observing mixed spectrum generated by combining the optical signal to be measured with the phase conjugated light; and obtains the temporal waveform of the electric field of the optical signal by attaching the spectral phase to a separately observed spectrum of the optical signal to be measured.

Method and apparatus for measuring waveform of optical signal

An optical signal processing apparatus includes a first optical waveguide and a first slab waveguide configured to equally distribute an output light of the first optical waveguide. A first arrayed waveguide includes an aggregate of optical waveguides changing in optical length by a constant interval for dividing the output light. A second slab waveguide focuses the optical output of the first arrayed waveguide. A spatial filter receives incident light focused by the second slab waveguide and distributes the incident light on a straight line. The spatial filter also modulates the light into a desired amplitude according to the position on the straight line. The apparatus also includes a second arrayed waveguide and an aggregate of optical waveguides changing in optical length by a constant interval for applying light modulated by the spatial filter to the second arrayed waveguide. Structure is provided for converging the output light of said second arrayed waveguide to a single point. The resulting output light is then appiled to a second optical waveguide.

Optical signal processing apparatus and optical signal processing method

The present invention relates to an optical signal processing apparatus and optical signal processing method which enable generation, waveform shaping, waveform measurement, waveform recording, correlation processing, and the like of optical pulses of 1-10 ps. A basic construction of the optical signal processing apparatus includes an optical waveguide, a first structure for equally distributing output light of the optical waveguide, an optical waveguide comprising an aggregate of optical waveguides changing in optical length by a constant interval, a arrayed waveguide for dividing the output light, second structure for focusing optical output of the arrayed waveguide, and a mirror for receiving and reflecting incident light focused by the second structure. Or, the apparatus includes an optical waveguide, first structure for equally distributing output light of the optical waveguide, a arrayed waveguide comprising an aggregate of optical waveguides changing in optical length by a constant interval for dividing the output light, second structure for focusing optical output of the arrayed waveguide, and a spatial filter for receiving light focused by the second structure to distribute the incident light on a straight line and making desired amplitude or phase modulation of the light according to the position on the straight line and reflecting the light.

According to the process of the present invention for producing a garnet single crystal fiber, a crystal is grown while the direction of a seed crystal, corresponding to the direction of growth, is set in a direction having angles of at least 10.degree. from a direction equivalent to the &lt;100&gt; orientation, at least 20.degree. from a direction equivalent to the &lt;110&gt; orientation and at least 20.degree. from a direction equivalent from the &lt;211&gt; orientation. The resulting garnet single crystal fiber does not include a core, which is formed due to facet formation, and has an excellent optical homogeneity necessary for use in an optical device such as a laser device or an isolator.

Process for producing garnet single crystal

In a cavity dispersion measuring method, there are provided the steps of: dividing a light beam emitted from a laser cavity under measurement into first, second, third, and fourth light beams; propagating the first light beam and the second light beam along a first optical path and a second optical path respectively, and superimposing two light beams with each other which have passed through the first and second optical paths respectively to cause the two light beams to interfere with each other, thereby producing a first interference light beam; propagating the third light beam and the fourth light beam along a third optical path whose light path length is variable and a fourth optical path whose light path length is fixed respectively, thereby producing a second interference light beam; controlling the optical path length of the third light path in order that intensity of the second interference light beam is kept constant; adjusting the optical path length of the first optical path in correspondence with the controlled optical path length of the third optical path; measuring the first interference light to obtain a waveform of the light intensity while varying the optical path length of the second optical path in a vicinity; and Fourier-transforming the waveform of the measured light intensity to obtain phase information in a frequency domain, whereby wavelength dispersion of the laser cavity is obtained based on the phase information.

Cavity dispersing measuring method and measuring apparatus thereof

A method and apparatus for measuring ultrashort optical pulses is described. Pulse waveforms to be measured are the type which vary at high speed in a time close to or less than the response time of an optical detector. Changes of optical wavelength or frequency are measured at various sections of that pulse. The light to be measured is split into two beams, and recombined after provided with different delay times, respectively. The combined light is caused to enter a doubling crystal to generate a second-harmonic light, and the second-harmonic light component, or both the second-harmonic and fundamental components, is measured. The intensity shape and chirping of the pulses is obtained from the changes in the intensity of these components as a function of delay time difference by Fourier analysis including iterative arithmetic operations.

Method and apparatus for measuring ultrashort optical pulses

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Tokyo, Japan

Kazunori Naganuma