Commercial tunable polarization maintaining fiber couplers exhibit inadequate low polarization isolations. Utilizing a newly developed coupled mode theory, we theoretically analyze the performance of these devices, and conclude that these low values can be explained in terms of finite misalignments of few degrees between the two fibers' principal birefringent axes. We also show that for a given device with 3dB coupling ratio the polarization isolation critically depends on the transverse setting, and can vary between 18 and 40dB for the case of 5° misalignment, in a coupler composed of 3mm beatlength fibers.
|Number of pages||9|
|Journal||Proceedings of SPIE - The International Society for Optical Engineering|
|State||Published - 5 Jul 1989|