Square lattice photonic-crystal collimator

Abstract The anomalous dispersion of planar photonic crystals (PhCs) near the dielectric band edge is utilised to control the wavelength-dependent propagation of light. Light beams with up to ±10° divergence were cleanly collimated over a 40 nm (1260–1300 nm) bandwidth using a square lattice. The collimating range and angular dispersion sensitivity between the square and hexagonal lattice have been compared. Both the plane-wave expansion calculation and finite difference time domain (FDTD) simulation match well with the experimental results.