National Institute of Information and Communications Technology, Incorporated

Communications Research Laboratory, Independent Administrative Institution

Kazi Sarwar Abedin

Toshio Morioka

A fiber fuse detecting apparatus provides early detection of a fiber fuse generation in an optical fiber that propagates laser light, preventing the damage from expanding. It comprises light input means arranged on a laser light incidence side of the optical fiber that inputs at least a portion of reverse direction propagation light propagating in a reverse direction to light incidenting the optical fiber, light receiving means that photo-electrically converts light input by the light input means, electric filter means that extracts from an output signal of the light receiving means a prescribed frequency band component that contains a periodic signal due to fiber fuse, detecting means that detects change of or a prescribed value in output level of the electric filter means, and warning means that emits a warning signal in response to a detection output of the detecting means. The laser light to the optical fiber is stopped or reduced by means of the warning means.

Fiber fuse detecting apparatus

An optical dispersion measurement apparatus includes a device for generating a light beam; wiring for inputting the light beam to a first terminal of an optical distributor; wiring for outputting the input light beam as a plurality of light beams; an optical modulation device for modulating at least two of the light beams; an optical path via which the at least two beams are returned to the optical distributor; wiring for outputting the light beams returned to the optical distributor from a second terminal of the optical distributor; a device for detecting the light output from the second terminal; and a device for relating an intensity of the detected light to an optical modulation frequency that is used.

Optical dispersion measurement apparatus and measurement method using same

A mode-locked laser apparatus includes a mode-locked laser oscillator, a detection device for detecting changes in the optical path length of the mode-locked laser oscillator by utilizing the chromatic dispersion characteristics of the optical path, an optical path length controller that controls the optical path length of the laser oscillator, and a feedback circuit that controls the optical path length controller by means of the signal detected by the detection device.

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Cambridge, MA, United States of America

Kazi Sarwar Abedin