Sumitomo Electric Industries, Limited

Sei Optifrontier Co., Ltd.

Sumitomo Electric Optifrontier Co., Ltd.

Sumitomo Electric Lightwave Corp.

Fujitu Limited

Tetsufumi Tsuzaki

Masayuki Nishimura

Toshiyuki Miyamoto

Motoki Kakui

Kenichiro Otsuka

Yoshifumi Hishikawa

Tomohiko Ueda

Hitoshi Hatayama

Kazuya Masuda

Kiyotaka Murashima

Tsuneari Ito

Gouichi Fukumoto

Eisuke Sasaoka

Masaaki Hirano

Shinji Ishikawa

Takafumi Terahara

Masashi Onishi

Masayuki Shigematsu

Takashi Kondo

Yoshiyuki Suetsugu

Junichi Kumasako

Takashi Murakami

Tatsuhiko Shitomi

Fumiya Uehara

An inspecting device has an optical switch selectively coupling a light source unit with each of light input/output ports; a first light detecting unit detecting a first intensity of test light input from an inspecting device on a counterpart side and passing through the optical switch; a second light detecting unit detecting a second intensity of the test light directed from the light source unit toward the optical switch; a third light detecting unit optically coupled to another end of a test optical fiber having one end connected to each of the plurality of light input/output ports, and detecting a third intensity of the test light received from the light source unit via the test optical fiber; and an internal loss recording unit recording a loss of an optical path inside the device obtained on a basis of a difference between the third intensity and the second intensity.

Optical transmission path inspecting system, and optical transmission path inspecting device

A measurement system includes a measurement device including a light source, and a first power meter, and one or a plurality of connection members each configured to optically connect a pair of optical fiber lines of the plurality of optical fiber lines. A first optical fiber line of the pair of optical fiber lines includes a first end and a second end, a second optical fiber line of the pair of optical fiber lines includes a third end and a fourth end, the one or plurality of connection members optically connect the second end to the fourth end, the light source causes testing light to be incident on the first end, and the first power meter measures first intensity of first output light output from the third end by causing the testing light to propagate through the pair of optical fiber lines.

Measurement system

A measurement system is a measurement system inspecting an optical transmission line configured by connecting a plurality of optical cables, each of which includes a plurality of optical fibers, wherein the optical transmission line includes a plurality of optical fiber lines configured by connecting the plurality of optical fibers in the plurality of optical cables, the measurement system including: a first measurement device configured to be disposed at a first end of the optical transmission line; and a second measurement device configured to be disposed at a second end of the optical transmission line, wherein the first measurement device and the second measurement device perform a first measurement to inspect whether the optical cable is misconnected, and a second measurement to inspect the plurality of optical fiber lines in a case where it is determined that there is no misconnection in the first measurement.

Measurement system and measurement method

The present embodiment relates to an optical amplifier which can perform an amplification operation equivalent to a normal operation even with an increase of dark current in a PD forming a part of a light detection circuit for monitoring signal light as an amplification object. In the optical amplifier, a detection controller performs an anomaly determination on a light detection circuit due to an increase of dark current in the PD based on a difference between temporal change amounts of a signal component of a voltage of output signal from a light receiving unit including the PD, and a voltage component in a high frequency region included in the signal component. An amplification controller can perform suitable switching of control on a drive current to a pumping light source, based on the result of the determination.

Optical amplifier

The present invention relates to a Raman amplifier where flexibility in device design considering both of Raman amplification and dispersion compensation is high. In the Raman amplifier, the Raman amplification optical fiber included in the optical amplification section and the dispersion compensating optical fiber included in the dispersion compensation section are arranged while being optically connected to each other. Since the optical amplification section and the dispersion compensation section are provided as independent optical devices, one device can be designed without being restricted to the design conditions of the other device.

Raman amplifier and optical communication system including the same

The present invention relates to an analog optical transmission system having a construction for expanding an analog transmittable distance. The analog optical transmission system includes: a light transmitter outputting analog optical signals such as image signals modulated in accordance with electrical signals multiplexed on a frequency domain; a transmission line including a SMF of 20 km or less in the total length; and a light receiver. A dispersion compensating fiber compensating for the chromatic dispersion of the transmission line is arranged on the transmission line, and the dispersion compensating fiber satisfies one of the first condition that the chromatic dispersion is set at &#x2212;250 ps/nm/km or less and a length is set at 1.1 km or less, and the condition that the chromatic dispersion is set at &#x2212;330 ps/nm/km or less and a length is set at 1.2 km or less. Optical suppressing devices reducing the MPI noise are arranged at the end portion of the dispersion compensating fiber.

Analog optical transmission system

Raman amplification pumping light output from a pumping light source unit is supplied to a Raman amplification optical fiber through an optical circulator. The remaining Raman amplification pumping light is detected by a light-receiving element through an optical circulator and bandpass filter. Signal light that has reached a Raman amplifier propagates through the Raman amplification optical fiber while being Raman-amplified. A control section controls the power or spectral shape of Raman amplification pumping light output from each of N pumping light sources included in the pumping light source unit on the basis of the power of the remaining Raman amplification pumping light, which is detected by the light-receiving element. Hence, a Raman amplifier capable of easily controlling gain spectrum flattening in the signal light wavelength band can be obtained.

Raman amplifier

The present invention relates to an optical fiber component for Raman amplification having a construction for effectively suppressing deterioration of the transmission characteristic caused by amplification of scattered light components. The optical fiber component for Raman amplification has an optical fiber for Raman amplification and is inserted at a position where the effective deterioration amount of the optical SN ratio produced by DRBS-XT (Double Rayleigh Back Scattering-Crosstalk) is 1 dB or less at the signal output terminal of the optical fiber for Raman amplification.

Optical fiber component for Raman amplification, Raman amplifier and optical communications system

A optical filter has a loss spectrum whose gradient dL/d&#x3bb; of a loss L (dB) with respect to the wavelength &#x3bb; (nm) is variable in the wavelength band of multiplexed signal light. A control circuit detects each power of signal light components demultiplexed by an optical coupler and controls the power of optical pumping light to be supplied to an optical amplification section from an optical pumping light sources such that the power of output signal light has a predetermined target value. The control circuit also controls the gradient dL/d&#x3bb; of the optical filter on the basis of powers of the signal light components.

Optical amplifier and optical amplification method

The present invention relates to an optical communication system having a flat gain spectrum and an excellent pumping efficiency in a signal wavelength band, and comprising a structure which is realizable/operable at a low cost. This optical communication system comprises an optical transmission line including a plurality of Raman amplification optical fibers, and pumping light suppliers for supplying pumping light to the Raman amplification optical fibers. In particular, two Raman amplification optical fibers selected from the plurality of Raman amplification optical fibers included in the optical transmission line differ from each other in at least one of the wavelength at which the gain of Raman amplification becomes the highest, and the number of channels at which the gain of Raman amplification is maximum. Such a structure flattens the gain of Raman amplification viewed from the whole optical transmission line from a transmitter to a receiver within the signal wavelength band even when the gain spectrum of Raman amplification in each of the Raman amplification optical fibers included in the optical transmission line is not flat within the signal wavelength band.

Optical communication system

An optical transmission path in a Raman gain module ( ) for transmitting signal light input from an input terminal ( ) and Raman-amplifying the signal light by pumping light supplied from pumping light source units ( ) is formed by connecting in series two Raman amplification optical fibers ( ) having different wavelength dispersion values. According to this arrangement, wavelength dispersion in the amplifier module ( ) can be controlled using, e.g., the combination of the wavelength dispersion values of the Raman amplification optical fibers ( ). Hence, accumulation of dispersion into signal light and signal light transmission in an almost zero dispersion state are prevented, and degradation in signal light transmission quality due to the nonlinear optical effect is suppressed.

Raman amplifier module and optical transmission system using the same

Disclosed are a gain module and an optical communication system which have gain in a broad wavelength range and are of low cost. The gain module has two optical fibers and which differ from each other with respect to the composition of their respective optical waveguide region and which are connected in series. Because they differ from each other with respect to the quantity of their respective Stokes shift, they have gain in a different wavelength, respectively. The signal lights are introduced into the input end , amplified with the gain module in a wide wavelength range where an optical fiber has a Raman amplification gain, and are emitted from the output end .

Raman amplifier and optical communication system

The present invention provides a Raman amplification pumping module and others with a structure for effectively suppressing degradation of quality of signal light even with a breakdown in either one of a plurality of light sources. The Raman amplification pumping module is provided with light sources for emitting respective lightwaves with center wavelengths different from each other, and each of the center wavelengths of the lightwaves from these light sources is adjusted so that a difference between two center wavelengths selected therefrom is less than 6 nm.

Growing community of inventors

Yokohama, Japan

Tetsufumi Tsuzaki