Light transport in a graded photonic crystal is studied using the finite-difference time-domain technique. The photonic crystal consists of a square lattice of elliptical dielectric rods. Within a frequency window, light can propagate inside the photonic crystal with the beam width nearly unchanged. The propagation direction can be easily manipulated by the structure gradient, which is achieved by gradually varying the orientation of the elliptical rods. The degree of control over the flow of light can be modulated by changing the ellipticity. This provides a promising approach to design of optical devices for spatial-beam routing.
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