Title:  Ultrashort Pulses in Optical Microresonators with Kerr Nonlinearity

Committee: 

Dr. Adibi, Advisor        

Dr. Ralph, Chair

Dr. Wiesenfeld

Abstract: The objective of the proposed research is to study phase locking and self-synchronization phenomena in microresonator-based optical frequency combs (microcombs), and to utilize this understanding in devising techniques suited for the generation of on-chip ultrashort pulses in optical microresonators with Kerr nonlinearity. In particular, a systematic theoretical study of phase locking in microcombs pumped by a CW laser is presented and its predictions are experimentally verified by careful phase measurements of stable pulsed microcombs. This model clarifies the role of transition through chaotic states in the generation of temporal cavity solitons and is generic, in the sense that it can explain phase locking in any system with third-order nonlinearity, including cubic approximations of the fast saturable absorber in mode-locked lasers. The clarification of the role of modulational instability and chaos allows us to devise a set of techniques for the on-chip generation of ultrashort pulses. It is shown that by modulating the phase or amplitude of the pump laser, or through pumping the microresonator by two coherent lasers, it is possible to generate temporal solitons. In light of the recent demonstrations of fast on-chip optical modulators in integrated photonics, the techniques presented here, combined with on-chip optical modulators, pave the path towards demonstration of chip-based ultroshort pulse sources that can replace table-top pulsed lasers.