An optical switch, wherein the first and second output ports (optical
fibers) are disposed on the opposite sides of the input port (optical
fiber) so as to form acute angles with respect to the input port, the
input port and the first output port are optically coupled to each other
through a first mirror surface, and the input port and the second output
port are optically coupled to each other through a second mirror surface.
The incident angles of an incident light beam with respect to the mirror
surfaces are equalized, and optical path lengths between the input port
and the first and second output ports are equalized. The actuator inserts
and withdraws the second mirror surface on a position at the front of the
first mirror surface.