Strain sensing system using edge-reflection type acoustooptic tunable filter

An acoustooptic tunable filter (AOTF) with surface acoustic wave (SAW) on LiNbO₃ was applied to a wavelength monitor as a simple spectrum analyzer in a fiber-optic strain sensing system using fiber Bragg gratings (FBGs). In this paper, a new AOTF, which is smaller and more reasonable than a conventional AOTF with multi chips cascade connection, has been developed by using a reflection of light at an edge of the chip. Then this new AOTF, instead of an expensive optical spectrum analyzer, has been applied to the strain sensing system. As a result, advantages of light weight, small size, reasonable cost, fast response, no mechanical parts, high reliability and high accuracy have been confirmed in the system.