Experimental analysis of temperature response in a Sagnac interferometer using double-sense twisted low-birefringence standard fiber

In this work, we present an experimental investigation of the temperature-dependent transmission characteristics of a low-birefringence Sagnac interferometer incorporating a double-sense twisted fiber loop. The study focuses on the influence of wave retarder adjustments within the loop on the interferometric response over a temperature range of 25°C to 50°C. A 10-meter fiber loop, optimized for maximum transmission, exhibited an approximately linear transmission profile, achieving a sensitivity of 10.62µW/°C within the 35–50°C interval. In contrast, the 300-meter loop demonstrated a sinusoidal transmission behavior, with a sensitivity of approximately 140.03µW/°C observed between 30°C and 35°C. The comparative analysis reveals that the short-loop configuration offers stable and predictable linear response characteristics. In contrast, the higher sensitivity of the longer loop restricts its utility to narrower temperature windows. Hysteresis effects were consistently recorded in both configurations, suggesting dynamic thermal responses attributable to coil-induced birefringence. These results underscore the significant influence of temperature on the performance of Sagnac interferometers across a variety of industrial and scientific scenarios.