Towards Optical Hydrodynamics
Jason W. Fleischer, Assistant Professor of Electrical Engineering, Princeton
It is well-known, but underappreciated, that the basic equations of nonlinear optics can be mapped to equations from condensed matter physics. For example, the nonlinear Schrödinger description of paraxial beam propagation is identical to the Gross-Pitaevskii treatment of coherent matter waves, e.g. for Bose-Einstein Condensates. In turn, these equations can be mapped to Euler-like fluid dynamics using the Madelung transformation. Here, we exploit these relations to develop an optical hydrodynamics. Using coherent laser light in a nonlinear crystal, we directly observe ideal (inviscid) fluid behavior, including dispersive shock waves, peakon/cuspon formation, and vortex flow. Using spatially-incoherent light, we demonstrate all-optical plasma dynamics, including Landau damping, bump-on-tail instabilities, and weak and strong regimes of speckle turbulence. Theory is developed and shown to match very well with experiment. The results establish optical systems as an analog simulator for fluid behavior and hold potential for the design of new photonic devices.