Measuring modal birefringence along a holey fiber by photon-counting OTDR

A photon-counting optical-time-domain reflectometer (OTDR) with spatial resolution of 8 cm is used to measure the modal birefringence along a holey fiber. Modal birefringence of /spl sim/10/sup -6/ is successfully recorded at 650 and 835 nm. The birefringence measured by the OTDR well coincides with that obtained from the measurements of polarization-mode dispersion.