Simulation of sensing characteristics in optical nonlinear waveguide sensors

In this communication, we present an extensive theoretical analysis of a nonlinear waveguide structure sensor and derive the conditions for the maximum sensitivity of TE and TM surface waves. The waveguide sensor structure considered here consists of a dielectric film sandwiched between a linear substrate and a nonlinear cladding with an intensity-dependent refractive index. A computer program based on the derived mathematical modeling for simulating the propagation characteristics of various integrated optical nonlinear waveguide structures is developed. The theoretical requirements for reaching high sensitivity of the proposed nonlinear waveguide sensor are determined. Exact maximum sensitivity expressions for nonlinear surface waves in sensing schemes are obtained, which will allow the designer to find the work basis of maximum sensitivity and to create the right dimensioning of the proposed structure. Experiments with the above concepts could be demonstrated and carried out for future versatile sensors.