Wannier-function analysis of light propagation in linearly chirped superstructure Bragg gratings - art. no. 053802

We use a Wannier-function formalism to describe the optical Wannier-Stark l adder in superstructure Bragg gratings with a linear chirp. The coupled mod e equations are solved in a two-band approximation and an ansatz in which t he solutions are given by a superposition of Wannier functions. We find tha t the expansion coefficients are Bessel functions of integer order, as in t he case nf the one-dimensional Schrodinger equation with periodic potential in a uniform electric held. The analytical results are in good agreement w ith a numerical solution of the coupled-mode equations, particularly at low chirp values.