Thermal strain analysis in optical planar waveguides

For the first time, we derive an analytical form of the thermal-induced strain equation for the waveguide core layer in an optical planar waveguide, which is based on elastic interaction theory in multilayered isotropic structures off the edges by thin-film approximation. This derived equation addresses how material and structural characteristics affect the magnitude and the distribution of the strain. By this equation, the strain-induced birefringence can be reduced or eliminated by proper waveguide design.