Fabrication of photonic quasicrystals using multiple-exposure holographic method and bandgap properties

다중-노출 홀로그라피 방법을 이용한 광자 준결정 제작 및 밴드갭 특성

Two-dimensional photonic quasicrystal (PQCs) template patterns have been fabricated on a $1.1{\mu}m$-thick DMI-150 photoresist using a multiple-exposure holographic method. A 442-nm HeCd laser was utilized as a light source and the holographic exposure was carried out at a fixed angle of $\theta=6^{\circ}$. After the first holographic exposure, the sample was rotated to a proper angle and the second exposure was performed to the same manner. This exposure process was repeated n/2 times to obtain n-fold symmetric PQC patterns and then the sample was developed. The fabricated PQCs exhibited 8, 10 and 12-fold rotational symmetry and the diffraction patterns using a 632.8-nm HeNe laser were observed for n-rotation symmetry corresponding n-fold PQCs. The fabricated PQC template patterns were examined using scanning electron microscopy(SEM). Transmission spectra were measured fourier transform infrared(FTIR) spectrometer.