SURFACE EMITTING LASER AND OPTICAL COHERENCE TOMOGRAPHY APPARATUS EQUIPPED WITH SURFACE EMITTING LASER

A surface emitting laser according to the present invention includes a lower reflector, a first spacer layer, an active layer, a second spacer layer composed of a semiconductor material, a gap section formed of at least one of vacuum and gas, and an upper reflector in the written order, and also includes a control mechanism that changes a distance between an interface between the second spacer layer and the gap section and an interface between the upper reflector and the gap section. An optical path length neff×d extending from an interface between the lower reflector and the first spacer layer to an interface between the second spacer layer and the gap section satisfies a predetermined relationship.