| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problems that a signal-to-noise ratio is small because variation of a reflected light amount is very little even when a central wavelength is varied in an optical fiber Bragg grating (hereinafter referred to as FBG) used in an optical fiber distribution measurement system and a measurement value of the central wavelength extremely fluctuates due to external electromagnetic noise to a light reception element in a wavelength detector. <P>SOLUTION: A plurality of sensors made by connecting two ring waveguides by one optical directional coupler, incorporating a Bragg grating in one ring waveguide, and connecting the other ring waveguide to a signal transmission optical fiber by an optical directional coupler are connected in series. A comb type tunable filter capable varying the wavelength of the reflected light from the sensors is guided to an array waveguide grating of one-input multi-channel output. A wavelength band of each channel is equal to a wavelength band of the Bragg grating of each sensor. The temperature of each sensor is measured with a sufficient signal-to-noise ratio by measuring a tunable filter control voltage at which the channel output of each channel is the maximum. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
