Polarization Maintaining Fiber Optic Rotary Joint (PM FORJ)

For transmission of optical signals between units that are rotatable relative to each other fiber optic rotary joints (FORJs) are used both for single channel and multichannel operation. In applications where polarization state of the input light must be preserved a FORJ is replaced by polarization maintaining fiber optic rotary joint (PM FORJ). For the multichannel PM FORJ the basic constitutents of the device are image rotators like Dove prism and plarization retarderts like quarter wave plates (QWPs). The device is meant to be operated in both directions interchangeably. In this tehsis I have tudied the polarization transforming properties of the Dove prism and experimentally verified the resutls for the light of 1548nm. Further, I have carried out a complete theoretical as well as experimental study of the assembly which comprises two quarter wave plates seperated by a Dove prism such that it preserves circular states of polarization. This assembly is central to the functioning of the PM FORJ. In particular I have worked out the polarization transforming properties of this assembly with respect to an elliptic input light and azimuthal misalignments of the QWPs and experimentally verfied it. Finally, a complete model of the PM FORJ is developped based on the knowledge of the individual components comprising it. The experimental verfication of the behavior of free space part of the PM FORJ is carried out by studying an equivalent system.