Abstract: An interferometer-type laser sensor acts concurrently as a light source and to measure external physical quantities such as rotation, magnetic field, current and fluid velocity. The interferometer-type laser sensor has a laser resonator having a laser gain medium, optical path and two or more reflectors to reflect incident light toward an opposite direction. In addition, a device is provided for interfering light not reflecting on the said reflectors but passing through. A signal processor is provided to detect and process interference signal generated from the interfering device. The laser sensor has a distinction over the conventional passive fiber-optic gyroscope as followings: first, expensive polarization maintaining fiber or polarizer is not required, since there is no polarization error which is readily appeared at the conventional passive fiber-optic gyroscope.

Abstract: This invention relates to an all-fiber acousto-optic tunable wavelength filter which is useful in optical communications or optical fiber sensor systems. The present invention provides an all-fiber acousto-optic tunable filter, comprising: a length of optical fiber for propagating optical waves; a first mode converting means for selectively converting a core mode of the optical wave propagating in said optical fiber into a cladding mode by means of acoustic wave, depending on the wavelength of the optical wave; and a mode selecting means for selecting one or more mode among the core modes and cladding modes. In the embodiment of the invention, the mode selecting means may be configured to be a length of optical fiber whose jacket is partially stripped and a flexural acoustic wave generator to which electrical signal with a plurality of frequency components is applied. According to the invention, the wavelength filters provides a wide tuning range and can electrically control its filtering feature.

Abstract: This invention relates to a laser gyroscope. This invention provides a direction-switched mode-locked laser gyroscope, comprising: a laser resonator including a laser gain medium and an optical path, one end of the resonator being connected to a reflector and the other end of the resonator being composed of a Sagnac loop; wherein the gyroscope is operated by pulses generated from an optical switch connected to the Sagnac loop. The laser gyroscope according to the invention has a better durability than a conventional He-Ne type laser gyrocope. It can produce an output signal which can be processed more simply than that of the interferometric fiber-optic gyroscope since the output signal is characterized by frequencies corresponding to the rotation rate. The gyroscope operates to produce a pulse output, reducing lock-in effect compared with a gyroscope producing continuous wave output.