Tunability of Photonic Band Gap Notch Filters

A notch filter based on an index confined photonic band gap waveguide is proposed. The dropping of an electromagnetic wave having a specific wavelength is obtained by opportunely designing a periodically corrugated overlay. The selective filtering properties of the proposed structure are identified by using a computer code based on the bidirectional beam propagation method with the aid of the method of lines. The optimized design of a notch filter, characterized by a full-width half-maximum (FWHM) bandwidth of 2 nm, is given. The tunability is reached by exploiting the electroclinic effect of smectic-A * liquid crystals.