Rocking Filter in a Highly Birefringent Fiber for Resonant Coupling Between Different LP11 Modes and Generation of Cylindrical Vector Beams

We present a rocking filter in a highly birefringent two-mode fiber that enables resonant coupling between different modes in the LP11 group. Our simulations and experimental results prove that such a filter allows for resonant coupling between orthogonally polarized LP11 modes of the same spatial structure, as well as between modes of the same polarizations and orthogonal spatial distributions. Furthermore, we demonstrate that such rocking filters can be used to generate pure TE01, TM01 and HE21 beams or their coherent superposition.