Optical-wavelength-scale filters

Optical communications have reached bit-rates of 10 Gbit/sec and higher. Optical filters for optical signal processing can be constructed from coupled resonators. Wavelength scale resonators have sufficiently large free spectral range to span a communications bandwidth of several tens to several hundred of nanometers. If the bandwidths of the filters are large (10 GHz or larger), the Q's of the optical resonators appropriate for such bandwidths are realizable in several ways. Because the structures are small, they are also prone to radiate, suffering radiation loss. Radiation loss is of primary concern in the design of such structures. Three types of structures will be described in this talk photonic bandgap structures, waveguide ring resonators and channel dropping filters.