High Resolution Lithography as a Tool to Fabricate Quasiperiodic Crystals

Photonic crystal (PC) structures have attracted great attention for their property to forbid the propagation of the light at fixed wavelengths and the intriguing possibility to realize an all-optical integrated circuit for devices of new emerging technologies. Recently, important efforts have been dedicated to the realization of a new kind of photonic crystals, known as photonic quasicrystals (PQCs), in which the lack of the translational symmetry is compensated by rotational symmetries not achievable by the conventional periodic crystals. We studied, fabricated and characterized two-dimensional (2D) square Thue- Morse (ThMo) PQCs and 2D 8-fold symmetric aperiodically ordered PQCs with a multiple-beam interference-based spatial tiling. All the structures have been characterized by scanning electron microscopy and by optical diffraction measurements.