We demonstrate a highly sensitive temperature sensor based on a stress-induced high-birefringence-fiber Sagnac loop that uses a Nd-doped-fiber amplified spontaneous emission source. Relative temperature sensing is done in the spectral domain by shifts of a resonant wavelength and absolute temperature sensing by changes in separation between resonances . The measured relative change of these parameters with temperature in the range 15–110 °C, is , with measured fiber birefringence . This gives a wavelength-shift sensitivity of at and a resonance separation sensitivity of for . This telemetric point sensor has a loop length of 80 m, an operational bandwidth of more than 50 nm, and a temperature accuracy of better than 1 °C.
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