  Electromagnetic waves follow linear paths in homogenous index media, with the
exception of band edges. In this study, we introduced spatially distorted
photonic crystals (D-PCs) that are capable of beam-steering light waves, even
when a homogeneous refractive index is maintained. We analyzed their
equifrequency contours to investigate the correspondence between the direction
of distortion and the direction of the group velocity vector in the D-PC.
Thereafter, we experimentally verified the beam-steering phenomenon in the
terahertz range using an all-silicon D-PC. Our structures serve as on-chip beam
trajectory control without the need for any specially-engineered materials,
using only lattice distortion.
