Scaling Limits of MEMS Beam-Steering Switches for Data Center Networks

Transparent optical circuit switching can improve the aggregate bandwidth, scalability, and cost of data center networks provided, it can meet the performance requirements on switching speed, port count, and optical efficiency. Here, we examine the theoretical scaling limits of transparent nonblocking optical switches based on MEMS electrostatic tilt mirror devices. Using physical optics and electromechanics, we present a first principles analysis of how the response speeds of a set of canonical devices scale as a function of switch port count, crosstalk, and insertion loss. Our model indicates that the optimal actuator design (parallel plate versus vertically offset comb) and actuation method (digital versus analog) changes as a function of switch port count. It also suggests that conventional switch topologies do not allow a favorable tradeoff between switching speed and optical efficiency or crosstalk. However, high switching speeds can be achieved by multistage switch architectures such as the two examples we describe, a multiport wavelength switch and a wavelength-independent space switch.