Broadband Birefringent Half-Wave Plate

Abstract

We proposed a means of generating a broadband birefringent half-wave plate by sandwiching two A-plates, which can be partitioned into several regions. Each region differs in the wavelength of its incident light. The two A-plates have their slow axes in each region set at angles corresponding to the transmitted axis of the entry polarizer. By applying spherical trigonometry, and the 2×2 Jones matrix and Müller matrix methods, the input polarization state can be transformed to the same antipodal point. There exist some relations among the slow-axis angle and phase retardation value of the A-plates that should be satisfied. The software whose trade name is LCD Master is used to simulate the trajectory of the polarization state on a Poincare sphere. An undulation of Stokes parameters is observed, which may be suppressed by matching the refractive indices of the two media. An experiment on the stacking of commercial A-plates is conducted to further verify the feasibility of the proposed configuration. Finally, a method of fabricating a broadband birefringent half-wave plate is proposed. The transmittance spectra of a light-emitting diode (LED), a red, green, blue (RGB) color filter, and a broadband half-wave plate under a parallel polarizer are multiplied respectively in each region and resynthesized together. The resulting transmittance spectrum gives better suppression of light leakage over the visible range than that in the case of a single half-wave plate.