Research/Silicon Bulk Lens Scanners

Silicon Bulk Micro Lens Scanners†

|Silicon is trasparent for infrared wavelengths for fiber optic communication. We have transferred plano-convex profile of a thermally-reflow photoresist microlens into bulk silicon, and attached electrostatic actuators for lateral position control.

The picture on the left shows 2x2 lens scanners (lens diameter 260 microns, focal length 500 microns, chip dimensions 1 cm x 1 cm x 0.5 mm); a proof-of-concept model for MEMS OXC (optical crossconnect) using micromechanically adjustable collimator / micro scanning lens.

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Silicon Microlens†

Silicon microlens can be made by first making the starting spherical profile of photoresist by thermally reflowing it at high temperature (150 degC) and then by transferring the shape into silicon by using reactive ion etching (RIE) of SF6 and O2; delicate control of flowrate is needed to achieve appropricate profile (spherical) and smooth lens surface (within 10 nm roughness).

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Reference†

Kazuhiro Takahashi, Kunihiko Saruta, Makoto Mita, Hiroyuki Fujita, and Hiroshi Toshiyoshi, "An Optical Scanner with Electrostatic Comb Drive XY-Stage," IEEE/LEOS Int. Conf. on Optical MEMS and Their Applications (Optical MEMS 2004), Takamatsu, Japan, Aug. 22-26, 2004, pp. 56-57.
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