A Silicon Micromachined $f$- $\theta$ Microlens Scanner Array by Double-Deck Device Design Technique

Abstract

In this paper, we report an array of f- thetas microlens optical scanners developed for 3-D optical cross connect (OXC) system using the bulk-silicon micromachining technique. An electrostatic XY-stage mechanism for the 2-D lens scanner was designed to have a small footprint (2 mmtimes2 mm), compared with an integrated silicon lens (diameter 1 mm) due to the newly developed double-deck actuator design; all the mechanical parts (suspensions and frames) were made in the substrate layer of a silicon-on-insulator (SOI) wafer, and the electrostatic actuation mechanism (electrodes and electrical interconnection) was made in the SOI layer. A silicon lens was integrated on top of the XY-stage by transferring the spherical profile of a thermal-reflow photoresist pattern into the SOI layer by reactive-ion etching. The XY lens scanner was found to operate at lateral displacement of 19 mum in the X-directions and 23 mum in the Y-directions at drive voltages of 110 and 60 V, respectively. For an optical assembly of the OXC, we used additional lenses in a telescope formation to double the beam angle that was steered by the f- thetas microlens scanner by which the lens displacement could be designed to be smaller by a factor of 1/2