A novel variable optical attenuator and temperature sensor based on high-birefringence fiber-loop mirror

A novel variable optical attenuator (VOA) based on high-birefringence (HiBi) fiber-loop mirror is proposed. The HiBi fiber-loop mirror is put into the temperature-controlling box. As the temperature increases, the transmission spectrum shifts with nearly unaltered shape. The attenuation at 1558 nm is more than 30 dB with about 2.5-dB insertion loss. Meanwhile, the wavelength shift with the temperature is vigorously linear. In this scheme, we propose a temperature sensor with fairly good linearity of 0.9997. Moreover, using theoretical analysis and numerical simulation, we explicitly explain our experimental results.