Polarization Effects in Tilted Fiber Bragg Grating Refractometers

The polarization effects in tilted fiber Bragg grating (TFBG) refractometers are investigated theoretically. The polarization effects may degrade the sensor performance greatly, and should be considered to achieve high-precision surrounding refractive index (SRI) measurement. The possible paths to reduce the influence of polarization effects are discussed. For large SRI changes, the cutoff resonance wavelength can be used as sensing parameter to achieve a polarization insensitive SRI measurement with linear sensitivity of ~500 nm/u.r.i and SRI uncertainty of ~10-3over SRI range of 0.1; for tiny SRI changes the measurement can be refined by monitoring proper individual resonance (close to the cutoff resonance wavelength) with accuracy approaching 2.5 × 10-5over a SRI range of 0.001.