Large birefringence in two-dimensional silicon photonic crystals -: art. no. 161101

We report an experimental and theoretical study of the birefringence of two-dimensional photonic crystals in the spectral region below the first photonic band gap. Transmission spectroscopy is used to measure the birefringence of a sample composed of a triangular lattice of air cylinders in silicon: with a cylinder radius of 0.644 mum and a lattice pitch of 1.5 mum. The measured birefringence (defined as the difference in the effective refractive indices of the electric fields polarized parallel and perpendicular to the cylinder axis) reaches a maximum value of 0.366 near the first photonic band edge at a wavelength of 6.52 mum. The results show excellent agreement with theory and demonstrate the potential use of two-dimensional photonic crystals for highly birefringent optically integrated devices.