Optical Beam Steering Using Vertically Actuated MEMS Grating Coupler

The work demonstrates a novel MEMS tunable beam divider with vertical actuation and internally positioned grating. The internal placement of the grating within the waveguide core increases the coupling and the ability to change the effective index. The tunable grating coupler has an angular tuning range of similar to 7 degrees at 1550 nm wavelength with an actuation voltage of 5 V. It can provide >-4.7 dB coupling to the attached photodiode. The grating coupler has a beam width of similar to 0.95 degrees for a 100 mu m long grating, and it reduces to similar to 0.55 degrees for a 300 mu m long grating. Visible and near-infrared transparent materials used in the design allow its integration on the front side of a solar cell for simultaneous energy generation and communication. Keeping the tunable grating coupler on the back side of the solar panel will eliminate the estimated 15% reduction in the solar cell efficiency caused due to front-side integration. This system can co-exist with other radio-based communication transceivers and provide additional bandwidth, redundancy, or LiDAR imaging capability, without adding significant weight or consuming more area.