An all-optical fiber-optic switching device that maintains the signal as light from input to output. Traditional switches that connect optical fiber lines are electro-optic. They convert photons from the input side to electrons internally in order to do the switching and then convert back to photons on the output side.
Although some vendors call electro-optical switches "optical switches," true optical switches support all transmission speeds. Unlike electronic switches, which are tied to specific data rates and protocols, optical switches direct the incoming bitstream to the output port no matter what the line speed or protocol (IP, ATM, SONET) and do not have to be upgraded for any such changes. Optical switches may separate signals at different wavelengths and direct them to different ports.
Using tiny mirrors that reflect the input signal to the output port, MEMS technology is expected to be the prevailing method for building optical switches, also known as "photonic switches." There are various fabrication methods for building MEMS mirrors. See MEMS and transparent network.
MICRO ELECTRO MECHANICHAL SWITCHES
dBm = log10 (mW)*10