The dissertation will first review the background and previous work of liquid crystal beam steering technology in chapter one. In chapter two, we will investigate the causes and solutions of low efficiency for optical beam steering devices based on liquid crystal Decentered micro-Lens Arrays (DLAs).
In the following chapter three, we will focused on basic design and concepts of tunable liquid crystal polarization gratings with a nematic liquid crystal (LC) optical phase plate, with a large continuous in-plane gradient that is variable, and its application to a beam steering device with high efficiency. High steering efficiency of over 95% is demonstrated by modeling of the liquid crystal director field, and its effect on transmitted light. The period of the V-COPA grating can be varied by adjusting an applied voltage profile, which allows for continuous angular control of the diffraction angle. This continuous steering combined with such high efficiency is unprecedented.
To improve the important issue of tuning speed, in chapter four, we consider the dynamics of the LC polarization gratings. In this chapter we study the dynamics of discrete changes in the phase profile, and also continuous changes in the phase profile through acquired data and numerical modeling. We show that a design based on liquid crystals whose dielectric anisotropy can change sign (as a function of frequency) allows continuous tuning with reasonable response times.