The Department of Electrical Engineering

My research focuses on nonlinear optics within the broader context of general wave physics. The emphasis is on propagation problems that are universal to wave systems, taking advantage of the fact that optical systems allow easy control of the input and direct imaging of the output. Using a healthy mix of theory and experiment, my group studies both basic nonlinear physics and advanced design issues for photonic applications.

As a prime example, my group is developing optical hydrodynamics, in which the nonlinear propagation of light is described in terms of the equations for ideal fluid flow. For coherent (laser) light, the intensity acts as a fluid density while the direction of the wavefront gives an effective velocity. For incoherent light, the propagation can be treated as a statistical fluid, i.e. a plasma. Using these mappings, we have experimentally demonstrated optical shock waves, instabilities, turbulence, and thermodynamics.

There are two primary results of these mappings: (1) optical modeling and observation of fluid behavior that is difficult, if not impossible, to see by other means and (2) a framework for the discovery of new optical physics. 

If the optical waves carry information, then propagation can be leveraged for dynamical signal processing. For example, nonlinear wave mixing can result in (intensity-dependent) energy transfer between modes, enabling higher resolution, increase field of view, and improved signal-noise properties. Recently, we have generalized computational imaging to include spatial nonlinearity and are applying it to microscopy, phase retrieval, and imaging through scattering media. Particular areas of interest include digital holography, noisy imaging, and biomedical optics.