Broadband and ultra-broadband polarization rotators with adiabatic modular design

Abstract

We experimentally demonstrate broadband and ultra-broadband spectral bandwidth polarization rotators with modular design. The presented polarization rotators comprise arrays of half-wave plates rotated at different angles. We give the general recipe to determine the exact values of the rotation angles as follows: align the fast polarization axis of the first half-wave plate with the incoming polarized light, and then rotate each subsequent half-wave plate at a gradually increasing angle until the fast polarization axis of the last half-wave plate is parallel with the desired polarization rotation angle. We show that the broadband and ultra-broadband performance of the polarization rotators is due to the adiabatic nature of the evolution of the light polarization. In this paper we experimentally investigate the performance of broadband and ultra-broadband polarization rotators comprising ten multi-order half-wave plates and ten commercial achromatic half-wave plates, respectively.