Yokogawa Electric Corporation

Yoshihiro Sanpei

Yasuyuki Suzuki

Morio Wada

Makoto Komiyama

Shinji Iio

Kenji Ogino

Raiju Okada

Shuuhei Okada

Akira Miura

Hiroyuki Matsuura

Shin Kamei

Mamoru Hihara

Koki Iemura

An interferometer of the invention includes: a first splitting element which includes a first transparent medium and a first splitting film formed on the first transparent medium, and which splits incident light into a first split beam and a second split beam, the first split beam being the incident light reflected by the first splitting element and the second split beam being the incident light transmitted through the first splitting element; and a second splitting element which includes a second transparent medium and a second splitting film formed on the second transparent medium, and which causes interference between the first split beam and the second split beam passed through different optical paths, the second splitting element being positioned such that a positional relationship between the second transparent medium and the second splitting film with respect to a direction of incidence on the second splitting element of the first split beam is opposite to a positional relationship between the first transparent medium and the first splitting film with respect to a direction of incidence of the incident light on the first splitting element.

Interferometer, demodulator, and splitting element

A delay interferometer and a demodulator including the delay interferometer and a balanced photodetector are provided. A half mirror splits an optical signal into first and second split beams of light which travel on first and second optical paths, respectively. A first reflector being disposed on the first optical path reflects the first split beam of light toward the half mirror. The second reflector being disposed on the second optical path reflects the second split beam of light toward the half mirror. At least one phase compensator being disposed between the half mirror and at least one of the first and second reflectors includes a medium that exhibits thermooptic effect and has temperature dependency of refractive index. The half mirror couples the first and second split beams of light to generate at least first and second coupled beams of light.

Delay interferometer and demodulator

An interferometer of the present invention includes: a splitting element which splits an incident light beam into a first split beam and a second split beam; and a first phase compensator which is positioned in an optical path of the first split beam, and which compensates a phase difference occurring between the first split beam and the second split beam upon splitting of the incident light beam by said splitting element.

Delayed interferometer enabling a reduction of polarization-dependent frequency shift and demodulator

A demodulator includes: a Michelson interferometer having: a half-mirror which splits an optical signal, emits a first split light to a first optical path, and emits a second split light to a second optical path; a first reflector which reflects the first split light to the half-mirror; and a second reflector which reflects the second split light to the half-mirror, wherein the half-mirror recombines the first split light and the second split light, and emits a recombined optical signal while splitting the recombined optical signal; and an balanced optical detector which receives the recombined optical signals from the Michelson interferometer, and generates a demodulated signal based on the two recombined optical signals. The length difference between the first optical path and the second optical path is set so that the second split light has a delay time equal to a one-bit period, with respect to the first split light.

Optical signal demodulator

The present invention is intended to realize a spectrometer which improves the wavelength resolution without being affected by the pitch of the photodiode array. The present invention is characterized by a spectrometer which comprises a wavelength dispersion device spectrally dividing the measured light beam and a photodiode array composed of a plurality of photodiodes that detect the spectrally divided light beams by the wavelength dispersion device and output photocurrents, and performs measurement using the outputs of the photodiode array; providing a deflecting means that deflects the measured light beams and changes the position where the measured light beams are detected by the above photodiode array, and measuring the characteristics of the measured light beam from the measured results for different deflection amounts.

Spectrometer

The present invention relates to a spectrometer whereby the accuracy of wavelength measurement can be improved without being affected by the environment of use. The present invention is characterized by improvements made to a spectrometer for spectrally dividing the light under measurement by transmitting the components thereof at different, wavelength-by-wavelength angles, and receiving and detecting the light under measurement thus spectrally divided by the chromatic dispersion device using an optical detector. The apparatus according to the present invention comprises a refractive index compensation means for compensating changes in the angle at which the chromatic dispersion device transmits the light under measurement, according to changes in the refractive index of the medium in which the chromatic dispersion device is placed.

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Musashino, Japan

Yoshihiro Sanpei