Abstract: Optic-fiber temperature sensor is an instrument required in high voltage environment. We make the optical coupler more sensitive to temperature by elongating the couple length. Therefore, it can be used to measure temperature. It has good reliability and repeatability since no additional materials are used. This research investigates linearity and sensitivity of couplers with different coupler length. R of the present example in the experiment has reach 0.7% per degree Celsius when the temperature ranges from -40 ℃ to 90 ℃, and it has good linearity and repeatability.

Key words: coupler length, distribute change rate, fused-tapered fiber coupler