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 photo nic band gap. Transmission spectroscopy is used to measure the birefringenc e 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 me asured 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 ba nd edge at a wavelength of 6.52 mum. The results show excellent agreement w ith theory and demonstrate the potential use of two-dimensional photonic cr ystals for highly birefringent optically integrated devices.