Waveguide polarization-independent optical circulator using a Mach-Zehnder interferometer

We propose and realize a new polarization-independent optical circulator using a Mach-Zehnder interferometer which does not need a polarization-beam splitter. We obtain 14.1-23.7 dB isolation and 3.0-3.3 dB insertion loss at /spl lambda/=1.55 /spl mu/m.