Abstract

We derive an expression for the complex amplitude reflectance of the liquid crystal light valve (LCLV) as a function of the writing intensity and applied voltage. The input and output polarizers are assumed to have arbitrary directions. The twisted nematic liquid crystal is modeled as multilayers of uniaxial crystals with rotating optic axis, and the Jones matrix describing round trip transmission is determined. Molecular tilt along the device axis, which results from the electric field, and the corresponding value of the extraordinary refractive index are assumed homogeneous. The theoretical results match our experimental measurements of the magnitude and phase of the reflectance in all conditions. This theory allows us to optimize the operation of the LCLV as an intensity or phase-only spatial modulator. When the polarizers are orthogonal and the input polarizer is at 34° with the front liquid crystal director, the intensity reflectance reaches 100% (compared to 81% for the conventional configuration). Phase-only modulation is achievable by use of appropriate applied voltage bias, with a maximum of 11% intensity distortion.

© 1989 Optical Society of America