Fabrication of 3D photonic structure on glass materials by femtosecond laser modification with HF etching process

In this study, a novel method of an array of square columns with high aspect ratio (about 10) on quartz and a pattern of complex multi-layered woodpiles on slide glass are firstly fabricated by femtosecond laser inner modification with hydrofluoric acid (HF) etching. The three-dimension (3D) patterns composted with embedded gratings are scribed by femtosecond laser focused inside the bulk materials with the central wavelength of 517 nm, the repetition rate of 100 kHz, the pulse width of 350 fs and the power of 100 mW. For the quartz glass, a high aspect ratio (about 10) structure of squared column array with the width of 10 μm and the height of 100 μm is formed from a grid pattern etched by 15 wt% HF for 15 min and 5 wt% HF for 90 min. For the slide glass, a 3D piled-octahedron structure with the feature size of 10 μm is developed from a multi-layer woodpile pattern etched by 5 wt% HF for 2 h. Moreover, the optical band structures of both 3D structures are calculated by the plane wave expansion method. And then, the defect effect of light propagation with sample paths on square and piled-octahedron structures are designed to verify the optical characteristics by finite difference time domain (FDTD) simulation in this study.