Birefringent filters in fiber systems

Birefringent filters (or Lyot filters, as their implementation is most widely used in lasers) are popular radiation wavelength selectors. Their adaptations to fiber lasers are quite diverse and feature many original solutions. This work analyzes various configurations of Lyot filters in fiber lasers and discusses modifications of these filters under new conditions. The question is further discussed regarding the possibility of choosing the initial birefringence value in the discrete and fiber-optical implementations of the filter, and of subsequent birefringence adjustment. Also, the prospects of electronically controlled Lyot filters and their application in fiber-optical sensors are explored. Peculiarities of all-fiber Lyot filters are demonstrated in comparison to their conventional implementations.