Polarization-adjustment-free phase error measurement of an arrayed-waveguide grating by optical low coherence interferometry

We report that the phase error distribution of an arrayed-waveguide grating can be measured precisely without adjusting the state of polarization in either arm of the interferometer. This is achieved by combining a 90/spl deg/ Faraday rotator and a polarizer with a depolarized light source in a conventional fiber-optic Mach-Zehnder interferometer.