Polarization-dependent refractometer for discrimination of temperature and ambient refractive index

Transmission characteristics of polarization-dependent refractometer based on a surface long-period grating (SLPG) inscribed in a D-shaped photonic crystal fiber (PCF) are investigated. The birefringence of SLPG produces the separation of transmission spectra for TE and TM polarization modes. We also measure the sensitivities of PCF-based SLPG to temperature and external refractive index change depending on the input polarization states. The SLPG-based sensor exhibits different temperature and ambient index sensitivities corresponding to TE and TM polarization modes. Therefore, the SLPG inscribed in D-shaped PCFs can effectively discriminate temperature and ambient index sensitivities.