The Fabrication And The Optical Properties Of Two-dimensional Thue-Morse Quasicrystals

Quasi-periodic photonic crystals is a kind of crystals which is between periodic photonic crystals and disordered structures and its lattice arrangement is generated according to certain quasi-periodic sequence rules. In this paper, we studied the optical properties of two-dimensional Thue-Morse quasicrystals.Firstly, a large area two-dimensional Thue-Morse quasicrystal with nanometer structures is fabricated on poly methyl methacrylate(PMMA)substrate. The two-dimensional Thue-Morse quasicrystal has been experimentally obtained by removing particular lattice points from a regular square array by the technology of electron beam lithography (EBL), and its morphological features are characterized by scanning electron microscope (SEM). The samples with high spatial resolution demonstrate that EBL technique can be used to fabricate quasi-periodic photonic crystals.Then optical properties of the sample are studied by the far field diffraction experiment, and the diffraction pattern is very obvious and clear. Thought the discussion of the relationship of diffraction pattern and incident wavelength, incident angle, the distance between incident light and the sample, the distance between the sample and the screen, respectively, we concluded that diffraction pattern of the sample only depended on its own structure.Finally, according to the diffraction principle , the interference and Fourier optics theory, the far field diffraction patterns of Thue-Morse quasicrystal are simulated numerically and analyzed, a generalized method to study quasicrystal photonic structures has been summarized. It is shown that the theoretic simulations are consistent with the experimental results very well. For increasing the order of quasicrystals structrures the spectra reveals a constant self-similarity, this feature denotes the existence of a fractal scaling law, which impacts transmission properties of photonic bandgap of the aperiodic lattices. The optical properties of two-dimensional Thue-Morse quasicrystals will open up a new way of the designing and production of the photonic band gap devices and diffractive photonic devices.