Enhanced linear and nonlinear optical phase response of microring resonators for engineerable photonic media

摘要

Microring resonators can serve as key elements in the realization of engineerable photonic media. A sequence of resonators coupled to an optical waveguide can be viewed as an optical transmission line with highly controllable dispersive and nonlinear properties, similar to those of photonic crystals or gratings. We have constructed and characterized several optical micro-ring resonators with scale sizes of the order of 10 microns. These devices are intended to serve as building blocks for engineerable linear and nonlinear photonic media. Light is guided vertically by an epitaxially grown structure and transversely by deeply etched air-clad sidewalls. In this work, we chose to construct ring resonators in AlGaAs and probe them at a photon energy below the half-gap of the material. Our motivation for this choice was to maximize the ultrafast bound (Kerr) nonlinearities resulting from virtual transitions while minimizing the two-photon contribution to carrier generation. We report on the spectral phase transfer characteristics of such resonators. We also report the observation of a pi-radian Kerr nonlinear phase shift accumulated in a single compact ring resonator evidenced by all-optical switching between output ports of a resonator-enhanced Mach-Zehnder interferometer.