Lattice Type Dependence of Transmittance Spectrum in Moth-eye Antireflective Structures

We have demonstrated that by changing the lattice type, it is possible to extend the anti-reflective bandwidth of terahertz moth-eye structures fabricated by femtosecond laser processing. We evaluated the transmission spectra of moth-eye structures with different lattice types both experimentally and numerically. The results showed that the hexagonal lattice moth-eye structure exhibits the broadest anti-reflection bandwidth with a 15% higher cutoff frequency than that of a conventional square-lattice moth-eye structure.