Microlens arrays of high-refractive-index glass fabricated by femtosecond laser lithography

作者：Nishiyama Hiroaki^*; Nishii Junji; Mizoshiri Mizue; Hirata Yoshinori

来源：Applied Surface Science, 2009, 255(24): 9750-9753.

DOI：10.1016/j.apsusc.2009.04.064

• Femtosecond laser
• 3D surfaces
• Micromachining
• Microlens

Microlens arrays of high-refractive-index glass GeO(2)-SiO(2) were fabricated by femtosecond laser lithography assisted micromachining. GeO(2)-SiO(2) thin glass films, which were deposited by plasma-enhanced chemical vapor deposition, have a refractive index of 1.4902 and exhibit high transparency at wavelengths longer than 320 nm. Using a femtosecond laser, three-dimensional patterns were written inside resists on GeO(2)-SiO(2) films, and then the patterns were transferred to the underlying films by CHF(3) and O(2) plasma treatments. This combined process enabled us to obtain uniform microlens structures with a diameter of 38 mu m. The heights of the transferred lenses were approximately one-quarter the height of the resist patterns, due to differences in the plasma etching rates between GeO(2)-SiO(2) and the resist. The lens surfaces were smooth. When 632.8-nm-wavelength He-Ne laser light was normally coupled to the lenses, focal spots with a diameter of 3.0 mm were uniformly observed. The combined process was effective in fabricating three-dimensional surfaces of inorganic optical materials.

• 出版日期2009-9-30