Optical communication with micromachined corner cube reflectors

Micromachined corner cube reflectors (CCRs) were demonstrated to transmit digital data optically across 150 meters indoors. These micro CCRs, made of gold-coated hinged polysilicon plates with dimensions of about 300{dollar}mu m,{dollar} had two fixed mirrors and one electrostatically actuated mirrors so that the CCRs could modulate incident light. Actuation voltages ranged from 15V to 37V, with bandwidth ranging from 500Hz to 3kHz and angular motions of up to 3 degrees. Largest (best) mirror radius of curvature was about 20mrad. Excellent mirror alignments was achieved using novel designs including tie-downs, tenon, and mortise. Divergence of reflected beams from typical CCRs was about 20mrad.; These micro CCRs were fabricated by a commercial foundry using a polysilicon surface micromachining process. All the working devices were manually assembled. Self-assembled CCRs using scratch-drive actuators were also investigated and demonstrated to be viable option for batch assembly of CCRs.; By reflecting incident light from a 4.2mW interrogating laser, CCRs devices successfully demonstrated data transmission across 150 meters at 4bps, consuming 16nW for mirror actuation. Low data rate was limited by our commercial off-the-shelf hardware. The experimental results not only support our CCR communication analysis but also strongly suggest that low-power long-range communication (greater than 1km) is achievable with suitable improvement of the CCRs' performance and the receiver system. Communication with multiple CCRs was also demonstrated, which suggests that CCRs can be used in applications requiring multiple communication channels. Small hand-held CCR-based communication units were also demonstrated.; Fabrication of micro CCRs using a commercial standard CMOS process was also investigated. A novel etching process using xenon difluoride (XeF{dollar}sb2){dollar} was developed to create hinged mirrors made of oxide, aluminum, and polysilicon by selectively etching away the supporting bulk silicon. Static corner cubes with dimensions of 200 to 250{dollar}mu m{dollar} were fabricated. With appropriate design modifications, CMOS micro CCRs with actuators and monolithic electronics should be possible.