Demonstration of the wide control range Q factor of ring cavity with ultrashort directional coupler and curved photonic-crystal ring waveguide

摘要

We extend the control range of the Q factor of a ring cavity that consists of a photonic crystal. The control range, which determines the storage time (high Q) and efficiency of input and output (low Q) of light, is required to be wide for the random-access memory of an optical pulse train. The conventional photonic-crystal ring cavity with a directional coupler and a hexagonal-shape ring waveguide has a very narrow range. We replace these components by a directional coupler having flat dispersion and a circularly curved ring waveguide. We experimentally varied the Q factor by thermal modulation of the device and achieved a control range between 1.9 × 10 ~3 and 1.7 × 10, ~4.