Sensitivity and Evanescent Field Study of a Uniaxial Anisotropic Planar Waveguide Based Optical Sensor

Abstract

The effect of source, geometrical and physical parameters of slab waveguide on the sensitivity of optical sensor and its evanescent field have been investigated. The waveguiding film of LiNbO3 was fabricated and the observations revealed that the maximal sensitivities of Transverse Magnetic (TM) modes and their corresponding frequencies are greater than those for Transverse Electric (TE) modes. Furthermore, the optimal source parameters improve the maximal sensitivity and evanescent field in the cover. However, the increment in the core thickness reduces the sensitivity of sensor due to reduction in evanescent field in the cover. The sensitivity of sensor was observed as a function of refractive indices of cover, core and the substrate. The increase in refractive indices of cover and core, directly affect the sensitivity while an inverse relation has been observed regarding increase in the refractive index of the substrate. It is worth noting that, any changes in the physical parameters of waveguide sensor show an insignificant effect on the evanescent fields.