Known forms of switched optical communication systems incorporate fiberoptics as a medium for communicating messages carried by modulated beams of radiant energy. Such messages at times need to be switched between optical fibers. One known form of optical switch is a crossbar switch.
Known optomechanical crossbar switches use moving mirrors to create connections between inputs and outputs. Various mechanisms can be used to switch or move the mirrors or otherwise to cause them to be actuated and to be in a state to create a connection.
FIG. 1 illustrates a known optical crossbar switch module 10 having four inputs and four outputs. Such switch modules receive a plurality of modulated light beams to be switched at input ports such as ports 12-1, 12-2, 12-3, 12-4 . . . 12-N. Switched light beams exit module 10 at output ports 14-1, 14-2, . . . 14-N.
The rectangles inside module 10 represent mirrors. The gray rectangle 16 is a fixed mirror. The dashed rectangles 20a-20k are non-actuated mirrors. Nonactuated mirrors permit beams to pass without substantial deflection. The black rectangles 22a-22d are actuated mirrors. Actuated mirrors substantially deflect incident beams.
In the example of FIG. 1, input ports 12-1, 12-2, 12-3, and 12-4 are coupled to output ports 14-2, 14-3, 14-4, and 14-1, respectively. Actuating the appropriate correct set of mirrors enables the switch to make all connection permutations.
Lenses, such as lens 18a, at the inputs and outputs of switch module 10 keep the light beams collimated while traversing the free space inside the optical switch. Fibers provide inputs to and transmit outputs from the switch 10 and they are precisely aligned to the collimating lenses. The number of switchable mirrors required in this architecture is N2−1.