High aspect ratio SiO₂ pillar structures capable of the integration of an image sensor for application of optical modulator

This paper presents an optical window capable of the integration of an image sensor for the application of optical modulators. The optical window consists of high aspect ratio SiO₂ pillars that can modulate the transmission light intensity by moving a liquid in and out of the spaces between pillars. The high aspect ratio SiO₂ pillar structures are fabricated by reactive ion etching (RIE). SiO₂ pillars together with smooth surfaces, vertical shapes (base angle ~ 89.5°) and high aspect ratio of 12 with a depth of 12 μm, diameter of 1 μm, and the pitch of two pillars of 2 μm have been achieved. An optical window with and without liquid penetration area integrated with an image sensor for an optical mo dulator has been successfully demonstrated. A high transmission modulation together with a large contrast have been observed of approximately 65% and 0.86 for cases with and without matching oil penetration, respectively.