  This study presents active beam steering and afocal zooming of light by
incorporating liquid crystals (LCs) with graded index photonic crystal (GRIN
PC). The GRIN PC structures are composed of low refractive index polymer
annular rods having gradually varied radii of holes. To actively manipulate
incident light, the annular rods are infiltrated with nematic LCs. By applying
an external voltage to the infiltrated LCs, the effective index profile of the
low-index GRIN PC structure is modulated without introducing any mechanical
movement. The incident beam deflection and corresponding focal distance
modulation are tuned only by controlling the applied bias voltage. In the
present work, hyperbolic secant refractive index profile is chosen to design
GRIN PC structures. To design GRIN PC structure with annular PCs,
Maxwell-Garnett effective medium approximation is employed. Moreover, we
analytically express the relation between infiltrated LCs and gradient
parameter to show the physical background of the tuning ability of the proposed
devices. Also, beam steering and afocal zooming devices are analytically
investigated via geometrical optics and numerically realized with the help of
the finite-difference time-domain method. A beam deflection with an angle
change of {\Delta}{\theta}out= 44{\deg} and a light magnification with maximum
x2.15 are obtained. LCs are inexpensive materials and work under low
voltage/power condition. This feature can be used for designing an
electro-optic GRIN PC device that can be useful in various optical
applications.
