Nippon Telegraph and Telephone Corporation

Ocean Cable Co., Ltd.

Takeshi Imai

Takuya Kanai

Kota Asaka

Yumiko Senoo

Nobuyuki Yoshizawa

Akira Mochizuki

Tadatoshi Tanifuji

Kazumasa Nemoto

Yasuo Ishino

A wavelength-selective optical reception device includes a photoreceptor () that converts optical signals () into electric signals and outputs the electric signals, a base () on which the photoreceptor () is provided, a housing () that is mounted on the base () and surrounds the photoreceptor () along with the base (), and that is provided with a window () to pass optical signals () including the optical signals () and including optical signals () of a wavelength different from a first wavelength of the optical signals () and a window () to pass the optical signals (), and an optical filter () that is disposed inside the housing between the window () and the photoreceptor () along the optical axis () of the optical signals (), and that outputs, out of the optical signals () that enter thereto, the optical signals () toward the photoreceptor (), and reflects the optical signals () toward a near side in a direction of travel of the optical signals ().

Wavelength-selection type optical receiving apparatus

A station-side telescope included in a station-side optical antenna unit is configured to transmit and receive an optical signal, a guide light source is configured to emit guide light in a direction of orientation of the station-side telescope, a node-side telescope is configured to transmit and receive an optical signal, a node-side control unit included in a node-side optical antenna unit is configured to generate and output a control signal for moving a node-side base based on a position of the guide light included in an image obtained by a camera capturing the guide light emitted by the guide light source so that a direction of orientation of the node-side telescope faces the direction of orientation of the station-side telescope, an antenna drive unit is configured to receive the control signal and generate and output a drive signal based on the control signal, and the node-side base included in the node-side optical antenna unit is configured to support the node-side telescope and receive the drive signal to change a direction of orientation of the node-side telescope.

Optical space communication system and optical space communication method

An optical wavelength selecting filter-module into which light is incident from a prescribed direction determined in advance, the optical wavelength-selective filter module including: an optical filter of which an orientation can be changed; a frequency information acquiring unit which acquires frequency information that is information indicating a frequency of light to be transmitted through the optical filter; a temperature information acquiring unit which acquires temperature information that indicates a temperature of the optical filter; a determining unit which determines an orientation of the optical filter based on relationship information that is information associating, for each prescribed frequency, the temperature and an orientation of the optical filter at which light of the frequency is transmitted through the optical filter at transmittance equal to or higher than prescribed transmittance at the temperature, a temperature indicated by the temperature information, and a frequency indicated by the frequency information; and an actuator which points the optical filter in an orientation having been determined by the determining unit.

Optical wavelength selecting filter-module and optical wavelength selecting method

A wavelength-tunable optical filter control apparatus in an optical access system that uses wavelength-multiplexed optical signal of a plurality of wavelength channels includes a wavelength-tunable optical filter configured to pass an optical signal of a specific wavelength channel among the plurality of wavelength channels; a light receiving element configured to convert the optical signal that has passed through the wavelength-tunable optical filter into an electrical signal; a signal quality determining unit configured to determine a quality of the electrical signal; and a wavelength-tunable optical filter control unit configured to acquire a light intensity of the electrical signal and control a wavelength of the wavelength-tunable optical filter based on the acquired light intensity and a determination result of the quality of the electrical signal.

Tunable optical filter control apparatus and tunable optical filter control method

A submarine, optical-fiber cable having a central metal wire, a slotted rod surrounding the wires, an absorbent sheath surrounding the slotted rod, a plurality of strength members helically wound around the absorbent sheath, a metal jacket surrounding the strength members, and a plastic sheath surrounding the metal jacket. The slotted rod includes peripheral helical slots, and each of the slots may receive at least one optical fiber or at least one optical ribbon. The optical ribbon includes at least two optical fibers. Each of the optical fibers has a tensile strain ranging from about 0.015 to 0.3% along its axis. The absorbent sheath includes a layer surrounding and contacting the slotted rod for absorbing water. The cable is suitable for operating in deep sea beds for a long period of time, for laying and recovering cables, and for quick repair. Modulated strain distribution in the optical fibers suppresses stimulated Brillouin scattering therein.

Growing community of inventors

Musashino, Japan

Takeshi Imai