Ultrashort pulses, Solitons, and Bio-Imaging
Nature is nonlinear, which allows for complex and beautiful dynamics and patterns from turbulence and chaos to fractals and self-similarity. Nonlinear optical systems are relatively simple and therefore provide an ideal testbed to explore universal concepts in nonlinear pattern formation. One archetypal nonlinear pattern is the solitary-wave (or soliton), which is a wave-packet that propagates without change. In addition to its intrinsic interest, the soliton plays a major technological role in the generation of ultrashort (femtosecond) pulses from laser sources, demonstrating the impact possible from new discoveries in this field. Research in the group involves theoretical and experimental exploration of nonlinear optical processes in bulk, fiber, and nanophotonic systems. Stable patterns are applied towards applications like nonlinear imaging deep into the brain. See some of our recent work on chirped and stretched-pulse generation in Kerr resonators.
Optomechanics in fiber and micro-structured waveguides
Brillouin scattering is a nonlinear optical 
effect involving the interaction of light with sound. Studied since the early days of nonlinear optics, stimulated Brillouin scattering is one of the strongest nonlinear optical effects and has enabled technological advances for sensing, microwave processing, slow and fast light, high coherence source generation, and optical phase conjugation. Recent years have seen a surge of interest in a type of Brillouin scattering that occurs in systems where both light and sound are supported by a waveguide. This type of Brillouin scattering is highly tunable and is advantageous for microwave processing, tunable source generation, and ultrafast processing. Remarkably, new types of optomechanical interactions are still being discovered and explored as the field continues to grow. Our group is pushing this nonlinear optical frontier and also applying these interactions toward novel technologies. See our recent results on strong coupling to ultra-long lived phonons in tapers here.
Traveling-wave optomechanics for quantum information control
At room temperature, the high frequency acoustic waves generated by Brillouin scattering rapidly decay into the environment. At cryogenic temperatures, these same phonons can last several orders of magnitude longer, which substantially enhances the interaction and enables a new world of photon-phonon dynamics. Much like the radiation pressure mediated interaction in cavity optomechanical systems, this electrostriction mediated traveling-wave optomechanical interaction enables a new platform for quantum information processing, ultrasensitive metrology, and fundamental tests of quantum decoherence. This Brillouin-like coupling provides optical access to ultra-long lived phonons in any transparent material, which is highly desirable for new technologies as well as for basic material science. The group is exploring new directions in traveling-wave optomechanics both theoretically and experimentally. See our recent results on surface acoustic waves here.