Reflectivity of integrated optical filters based on elliptic Bragg reflectors

Spectral properties of integrated optical filters and wavelength division multiplexers where Bragg reflectors composed of confocal elliptic grating lines are used for wavelength selection as well as focusing are calculated. It is shown that such reflectors can focus light from one focal point to the other focal point with almost unity reflectivity and diffraction-limited resolution. For most cases of practical interest, the reflection spectrum is almost identical to the reflection spectrum of a one-dimensional Bragg reflector