Simple polarisation-independent optical circulator for optical transmission systems

A simple polarisation-independent optical circulator has been developed. The circulator consists of a 45°Y3Fe5O12 rotator and a quartz rotator and two polarising beam-splitting cubes. Measured insertion loss was about 1.3 dB at 1.32 ?m wavelength. The circulator was connected to graded-index multimode fibres using rod lenses.