An optical tunable filter has a fixed substrate having a first recess
formed therein and a movable substrate bonded to the fixed substrate. The
movable substrate includes a movable portion having an opening formed at
a location facing the first recess and a support portion for supporting
the movable portion so that the movable portion can be displaced. The
optical tunable filter also has a light-transmittable substrate bonded to
the movable portion, a fixed reflection film formed on a bottom of the
first recess, and a movable reflection film formed on a surface of the
light-transmittable substrate. The optical tunable filter includes an
interference gap formed between the fixed reflection film and the movable
reflection film. The optical tunable filter also includes an actuator
operable to displace the movable portion relative to the fixed substrate.