Polarization-based refractive index sensor using dual asymmetric long-period gratings in ridge waveguides

We propose a sensor scheme operating in the wavelength band of 1460-1530 nm (S band) that utilizes two orthogonally polarized eigenmodes in a ridge-waveguide geometry by employing a pair of nonidentical asymmetric long-period gratings. Numerical simulations show a high sensitivity ~4900 nm/RIU (refractive index unit) over the refractive index range 1.33-1.34 exhibiting a relative resonance shift of 1 pm for an index change of ~10(-7). Such high resolution sensors enable detection of minute changes with potential applications to various biochemical industries.