title: Ring modulators with enhanced efficiency based on standing-wave operation on a field-matched, interdigitated p-n junction.
abstract: We propose ring modulators based on interdigitated p-n junctions that exploit standing rather than traveling-wave resonant modes to improve modulation efficiency, insertion loss and speed. Matching the longitudinal nodes and antinodes of a standing-wave mode with high (contacts) and low (depletion regions) carrier density regions, respectively, simultaneously lowers loss and increases sensitivity significantly. This approach permits further to relax optical constraints on contacts placement and can lead to lower device capacitance. Such structures are well-matched to fabrication in advanced microelectronics CMOS processes. Device architectures that exploit this concept are presented along with their benefits and drawbacks. A temporal coupled mode theory model is used to investigate the static and dynamic response. We show that modulation efficiencies or loss Q factors up to 2 times higher than in previous traveling-wave geometries can be achieved leading to much larger extinction ratios. Finally, we discuss more complex doping geometries that can improve carrier dynamics for higher modulation speeds in this context.
authors.forename: Fabio
authors.initials: F
authors.lastname: Pavanello
authors.forename: Xiaoge
authors.initials: X
authors.lastname: Zeng
authors.forename: Mark T
authors.initials: MT
authors.lastname: Wade
authors.forename: Miloš A
authors.initials: MA
authors.lastname: Popović