Optical stress sensor made via Ti-LiNbO3 coupler for robotic manipulations

The design and realization criteria of an integrated optic force sensor made via a X-cut titanium-diffused lithium niobate semi-asymmetric X-junction are presented. The X-cut crystal version whose force-perturbated permettivity tensor exhibits a longitudinal configuration, induces the propagation of guided modes with hybrid characteristics and substrate leaky modes. The field evolution is reported. This sensor configuration is less sensitive to the temperature changes and exhibits a better performance with respect to the Z-cut substrate geometry.The half-wave force is equal to 0.14 and 0.21 N for the TE-like and TM-like excitation, respectively, versus 0.32 and 0.23 N pertaining to a Z-cut waveguide.