Phase-type diffractive micro-optics elements in sulfur-based polymeric glass by femtosecond laser direct writing

Sulfur-based polymeric glasses are promising alternative low-cost IR materials due to their profoundly high IR transparency. In this Letter, femtosecond-laser-induced refractive index change (RIC) was investigated in one typical sulfur-based polymeric glass material, poly(S-r-DIB), for the first time, to the best of our knowledge. The RIC in the laser-engineered region was quantitively characterized, which laid a foundation for phase-type optical element design. By the integration of RIC traces, embedded phase-type micro-optics elements, including Fresnel zone plates, and a Dammann grating were fabricated in bulk poly(S-r-DIB) polymeric glass substrate via the femtosecond laser direct writing technique. The imaging and beam shaping performance were demoed in the near-infrared (NIR) region.