An Endless Reset-Free Polarization Control Method Using Two Wave Plates

We present a new, endless polarization control method based on two rotatable wave plates with variable birefringence. We propose two boundary conditions for the parameters of the wave plates so that this method will not have the pole problem. The pole problem is one of the main weaknesses in reset-free polarization controllers. We experimentally demonstrate the control principle of this method and verify its feasibility by using a simple feedback mechanism.