Ultra-fast and ultra-small photonic crystal/quantum dot all-optical switch for future photonic networks

摘要

We demonstrated a novel two-dimensional photonic crystal (PC) based Symmetric-Mach-Zehnder-type all-optical switch (PC-SMZ) with InAs quantum dots (QDs) acting as a nonlinear phase-shift source. The 600-μm-long PC-SMZ with integrated wavelength-selective PC-based directional couplers and other PC components exhibited a 15-ps-wide switching-window with a 2-ps rise/fall time at a wavelength of 1.3 μm. Nonlinear optical phase shift in the 500-μm-long straight PC waveguide was also achieved at sufficiently low optical-energy (e.g., π phase shift at ～100-fJ control-pulse energy) due to the small saturation energy density of the QDs, which was enhanced in the PC waveguide, without having to use conventional measures such as SOAs with current-injected gain. These results pave the way to achieving novel PC- and QD-based photonic integrated circuits including multiple PC-SMZs and other novel functional devices.