Optical and opto-mechanical structures in hybrid sol-gel materials for use in micro-optical systems

We are developing a silicon-based micro-optical table (MOT) on which various passive and active optical elements can be positioned with sufficient accuracy so that no further alignment is necessary. In order to achieve a zero-alignment assembly of micro-optical systems, we take advantage of lithographic patterning. Conventional lithography is used in combination with a deep reactive ion etch (DRIE) process for silicon (a.k.a as the Bosch etch) in order to pattern a silicon substrate that plays the role of a micro-optical table. Lithography is also used to pattern optical and opto-mechanical structures on optical elements. Specifically, the hybrid sol-gel method is employed in the fabrication of optical and optomechanical structures into a photosensitive glass material. High optical quality thick films and structures are fabricated by a one-step spin-coating process followed by direct UV imprinting. We have achieved a material thickness of 27.5 microns and a maximum patterned thickness of 17.4 microns at an aspect ratio of 0.6. The material exhibits a minimum transmittance of 97% between 400-1100 nm, an index of refraction of 1.49, and an rms surface roughness of 14.8 nm after development.