ABSTRACT
References ..................................................................................................................................... 313
Optical waveguide ring resonators, shown in Figure 5.1, are the simplest form of an integrated optical resonant structure. They were rst proposed by Marcatili1 and in the past several years photonic ring resonators have been investigated and demonstrated in several material systems including SiO2,2 Si,3,4 III-V semiconductors,5 and polymers.6 They have been demonstrated as passive wavelength lters,7,8 slow wave devices,9 and complex multipole lters.2 If the rings are made of an electro-optic material the resonant wavelength can be voltage or current tuned and the devices become optical switches or modulators. Tuning based on charge injection, depletion layer modulation, and the Pockel’s effect10 is in the literature. The modulation bandwidth or the switching speed is limited by the bandwidth of the resonator or the inherent speed limitation of the electro-optic effect. The highest speed devices are based on the Pockel’s effect.
