Concerning fiber optics, I'd like to know how a 2D MEMS based optical cross-connect is able to switch optical signals. I've read that these mirrors are controlled with electrical signals to be either "on" or "off" to redirect light to output ports.
As far as I know, all-optical based switches don't use buffers on the incoming data. However, an electrical signal must be generated to control the MEMS mirrors in order to redirect the signal to the output port. How can this electrical signal be fast enough to switch the optical signal? I assume this electrical signal comes from the header of the packet, but I'm not sure how an optical switch obtains that information and generates an electrical signal.