Modulated Retroreflectors

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In optical laser communication applications, it is sometimes important for communicating nodes to exhibit characteristics that include low power, small size, and low cost. Such applications are particularly important for an emerging class of sensor networks, in which many remote sensor nodes acquire data that is ultimately communicated to a higher-power interrogating source/receiver. A new modulated retroreflector device for use as a low-power, compact, economical, laser communication nodehas been developed at Boston University. A central concept is the use of a deformable MEMS mirror as one facet of a hollow retroreflector. The deformable mirror can be reshaped at tens of kilohertz using low-power electrostatic actuation, modulating the intensity of light that is returned to the source/receiver. A prototype system has been designed, built, and tested in a demonstration laser communication system. The modulator, presenting an aperture of ~5mm, requires less than 5mW to modulate with a contrast ratio of greater than 100:1, at an inter-node distance of 30m and a communication rate of 10kHz. A recent thesis presentation on this topic is summarized here..
 

 

Thomas Bifano, College of Engineering, Boston University, 8 St. Mary's St., Boston, MA 02215, (617) 353-8908, tgb@bu.edu