Analogue gravity from electrodynamics in nonlinear media

Working with electrodynamics in the geometrical optics approximation we derive an expression representing effectively curved geometries which guide the propagation of electromagnetic waves in material media whose physical properties depend on an external electric field. The issue of birefringence is addressed, and the trajectory of the extraordinary ray is explicitly worked out. Quite general curves are obtained for the path of the light ray by suitably setting the electric field.