Free-Space Communication for Autonomous Sensors using Grating Light Modulators David R. Pedersen, Michael H. Guddal University of California, Davis Olav Solgaard Stanford University

Outline Summary of Year 1 Milestones Improvements in GLM design Developed, modeled and characterized GLM Demonstrated free-space optical link using GCC modulator Improvements in GLM design Reduce angle dependence and dispersion Increase damping No interference with plasma => “buried” GLM Year 2 Milestones Integrate micromachined GLM with on-board power Buried GLM, through-the-wafer interconnects, wafer bonding

GCC Communication Link

High Contrast GLM Reduced Angle dependence Reflective State Diffractive State Increased damping

Full-wafer Grating Light Modulators Period: 10 Gap: 10um Beam Width: 10um Substrate/Beam Spacing: 2um Beam Length: 200um to 600um Beams: Doped low stress polysilicon Insulating Material: PSG

Lay out Each line: 2mm open-circuit region etched to the substrate and aligned with the front Front Backside contact to the substrate Back

Buried Grating Light Modulators - Technology Development DRIE trenches for interconnects and corner-cube reflectors Oxidation-smoothed TIR surface AR-coating GLM aperture

Autonomous Sensor Wafer with Buried GLMs

Conclusion Met Year 1 Milestones: Full-wafer fabrication process Fabricated and tested micro-machined GLMs Demonstrated free-space communication Full-wafer fabrication process Year 2 Milestones Integrate micromachined GLMs with on-board power, sensors, and electronics sources Technology development Buried GLMs Through-the-wafer interconnects Wafer bonding