Title:
MODE VARIATION DETECTOR
Document Type and Number:
Japanese Patent JPH01127924
Kind Code:
A
Abstract:
PURPOSE:To detect the mode variation by a miniature and inexpensive device of a simple constitution by converting a mode variation to an intensity variation by a multi-mode fiber, a mode scrambler and a star coupler. CONSTITUTION:A light beam 19 which is emitted from a semiconductor laser 1 is made incident on an isolator 2, propagated in a multi-mode through the inside of a multi-mode fiber 3, a higher order mode is eliminated by a mode scrambler 4, and several fundamental modes are selected. Subsequently, said light beam is further allowed to branch by a star coupler 5, and its output is detected by a photodetector 6. In such a state, for instance, when the wavelength of the laser 1 is fluctuated, a propagation mode excited in the fiber 3 is varied, and a mode propagation loss in the scrambler 4 and a branching ratio in the star coupler 5 are varied, therefore, a variation of the light intensity can be detected by the detector 6.
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Inventors:
ASAKURA HIROYUKI
HAGIWARA KIYOKAZU
NISHIOKA MINORU
IIDA MASANORI
HAGIWARA KIYOKAZU
NISHIOKA MINORU
IIDA MASANORI
Application Number:
JP28600487A
Publication Date:
May 19, 1989
Filing Date:
November 12, 1987
Export Citation:
Assignee:
MATSUSHITA ELECTRIC IND CO LTD
International Classes:
G02B6/14; G01J9/00; H01S5/00; H04B10/00; H04B10/071; H04B10/2581; (IPC1-7): G01J9/00; G02B6/14; H01S3/18; H04B9/00
Attorney, Agent or Firm:
Toshio Nakao (1 outside)