Influence of disorders on the focusing property of photonic quasicrystal slab

The influence of disorders in the fabrication process on the focusing performance of two-dimensional optical quasicrystal slab is investigated. Two types of disorders are considered: positional randomness and radius randomness. The change in field distribution for E polarization and H polarization is examined by using the finite-difference time-domain method. We find that for both polarizations disorder has a detrimental effect on the focusing performance of quasicrystal lens. The tolerance of the focusing function to structural disorders is examined in detail. We show that the focusing quality is much more sensitive to the fluctuation of radius than to the randomness of position. These results will be helpful in devising photonic imaging devices based on quasiperiod photonic crystals.