An optical switch having a plurality of switch cells. The optical switch has n
inputs (n is a natural number) and m outputs (m is a natural number). The optical
switch has a unit size defined as the distance between any two adjacent ones of
the switch cells. The optical switch comprises a substrate having a switch size
of KL (K is an integer satisfying nK, and L is an integer satisfying
mL), first and second mirrors parallel to each other and perpendicular
to a principal surface of the substrate, and an optical unit providing a plurality
of input optical paths for the n inputs and a plurality of output optical paths
for the m outputs. The plurality of input optical paths are inclined relative to
the first and second mirrors, and the plurality of output optical paths are inclined
relative to the first and second mirrors. Each switch cell comprises a switch mirror
provided movably relative to the substrate. With this configuration, the path dependence
of loss is substantially eliminated.
