Numerical analysis of the effect of small geometrical imperfections on photonic crystal wires

Imperfections in the geometry of photonic crystal wires (PCWs) are always a result of current manufacture techniques. The influence of such random defects on the propagating modes in PCWs is studied computationally by means of a full vectorial finite-element method using a perfectly matched layer (PML) as absorbing boundary condition, and the numerical results show a large sensitivity of the birefringence to the geometrical defects in the transversal section of the fibre. It has also been found that imperfections in PCWs have a greater effect on wave propagation than those in photonic crystal fibres (PCFs).