Polarization-insensitive planar lightwave circuit dual-rate Mach-Zehnder delay-interferometer

We demonstrate a silica waveguide Mach-Zehnder delay-interferometer that uses integrated switches to demodulate either 10- or 40- Gb/s differential phase-shift keyed signals. We made it polarization insensitive by using a half-wave plate and reducing polarization crosstalk in the couplers.