We study cascaded microring resonator (CMRR) configurations as general nonlinear phase-shifting elements that exhibit enhanced nonlinear sensitivity and flattened transmission characteristics. We show that even when the material itself has large two-photon absorption, CMRR devices with five rings facilitate a factor-of-10 enhancement of the optical nonlinearity when compared with a channel waveguide having the same group delay. In addition, high throughput in intensity can be maintained up to a 3π phase shift.
© 2003 Optical Society of America
Yan Chen and Steve Blair, "Nonlinear phase shift of cascaded microring resonators," J. Opt. Soc. Am. B 20, 2125-2132 (2003)