Highly compact asymmetric Mach-Zehnder device based on channel guides in a two-dimensional photonic crystal.

We have designed and fabricated a 2D photonic crystal (PhC) asymmetric Mach-Zehnder (M-Z) device structure using W1 channel waveguides oriented along ?K directions in silicon-on-insulator material. The asymmetric structure was designed using a PhC lattice with different filling factors. The asymmetry is obtained as a difference of two periods in the physical path length (DL=2a) between the arms, and it was sufficient to produce a pi phase shift in the region of operation around lambda=1500 nm. The asymmetric M-Z structure is more sensitive than a symmetric M-Z structure to changes in the refractive index and therefore becomes an interesting platform for switching and sensor devices.