Temperature-compensated fiber laser refractometer based on compact hybrid S-taper/FBG structure

A temperature-compensated fiber laser refractometer based on compact hybrid S fiber taper (SFT)/fiber Bragg grating (FBG) structure is proposed. The SFT is used as a sensing component as well as a band-pass filter (BPF) to tailor the FBG reflection, which has the micro size of 0.78 mm. Owing to the RI-dependence intra-cavity loss, the output power of the erbium-doped fiber ring laser (FRL) can be modulated by the surrounding refractive index (SRI). During the measurement range of 1.3330-1.4060, the refractometer provides a high sensitivity of 269.76 dB/RIU. By using the sensing matrix containing the SRI as well as temperature sensitivities for the output power and lasing wavelength, the temperature cross-sensitivity problem can be effectively resolved.