Ultralow-energy all-optical switches based on photonic crystal nanocavities

Abstract

Photonic crystal cavities having a wavelength-sized volume exhibit a strong light-matter interaction, which makes possible all-optical switches operating with ultralow energy consumption. Using the combination of an extremely small photonic crystal nanocavity and strong carrier-induced nonlinearity in InGaAsP, we have successfully demonstrated low-energy switching in the attojoule range for the first time. This switching energy is more than two orders of magnitude lower than that of previously reported optical switches. The ultrasmall cavity also contributes to fast carrier diffusion and hence a fast switching response of 20 ps at minimum. These all-optical switches with their small size and low-energy, fastresponse operation may open up the possibility of a dense photonic network on a chip.