Highly accurate spectral retardance characterization of a liquid crystal retarder including Fabry-Perot interference effects

Abstract

Multiple-beam Fabry-Perot (FP) interferences occur in liquid crystal retarders (LCR) devoid of an antireflective coating. In this work, a highly accurate method to obtain the spectral retardance of such devices is presented. On the basis of a simple model of the LCR that includes FP effects and by using a voltage transfer function, we show how the FP features in the transmission spectrum can be used to accurately retrieve the ordinary and extraordinary spectral phase delays, and the voltage dependence of the latter. As a consequence, the modulation characteristics of the device are fully determined with high accuracy by means of a few off-state physical parameters which are wavelength-dependent, and a single voltage transfer function that is valid within the spectral range of characterization.

Optical system for measuring the spectral retardance function in an extended range

“…This is due to a FabryPerot interference effect at the LC layer, as studied in Ref. [13]. For simplicity, we ignore here this secondary effect, and we will consider the retarder simpler approximation.…”

“…Similar spectral methods sequentially rotate the polarizers to achieve more data [11,12]. In addition, this kind of spectral measurements provide a simple test to identify whether the retarder presents multiple-reflection Fabry-Perot interferences [13].…”

Geometric phase ando-mode blueshift in a chiral anisotropic medium inside a Fabry-Pérot cavity

“…2(b) can be interpreted as an alternation of crossings and avoided crossings of transmission peaks [47,58]. Conditions (22) and (23) for the untwisted medium correspond to the respective conditions of sin 2 δ = 0 and sin 2 δ = 1. The Gooch-Terry minimum matches the twisted analog of a wave plate.…”

“…Points T and R show the frequencies of mode 3 for to and ro waves, respectively. G 1 and G 2 are Gooch-Terry minima (22) and G 3/2 is the Gooch-Terry maximum (23).…”

“…Fundamental photonic degrees of freedom-in transmittance [18][19][20][21], phase [22], and polarization [23]-can be efficiently controlled. Polarization control usually uses the Mauguin adiabatic waveguide mode [24] in a chiral anisotropic medium, particularly in a twisted-nematic (TN) LC layer inside the Fabry-Pérot cavity (TN-FPC) [25].…”