Narrowband, polarization-independent free-space wave notch filter

A two-dimensional-corrugated-slab-waveguide add/drop filter providing 100% resonant reflection at 1.55 mu m wavelength for both TE and TM polarizations with identical FWHM is designed. The fabricated device exhibits a reflectivity spectrum of more than 95% peak reflection for both polarizations at 1.537 mu m. The coupling scheme involves the TEO guided mode only; it is made relatively tolerant by means of a double-sided crossed grating. (c) 2005 Optical Society of America.