Rocking filter in a highly birefringent fiber for resonant coupling between different LP₁₁ modes and generation of...

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.