Surface emitting laser having a factor of equivalent refractive index constraint by scaled central wavelengths and optical coherence tomography apparatus equipped with such surface emitting laser

A surface emitting laser comprising:

• a lower reflector;
• a first spacer layer;
• an active layer;
• a second spacer layer composed of a semiconductor material;
• a central non-oxidized region within a peripheral oxidized region;
• a third spacer layer composed of the semiconductor material;
• a gap section formed of at least one of vacuum and gas;
• and
• an upper reflector,
• wherein the lower reflector, the first spacer layer, the active layer, the second spacer layer, the central non-oxidized region, the third spacer layer, the gap section, and the upper reflector are disposed respectively,
• wherein the surface emitting laser varies a wavelength of light to emit by changing a distance between an interface between the third spacer layer and the gap section and an interface between the upper reflector and the gap section, and
• wherein, expressions (1) and (3) are satisfied:
• (ma/2+ 3/16)λ0≦neff×d≦(ma/2+⅜)λ0 (1)
• (mb/2+ 3/16)λ0≦neff′×du≦(mb/2+⅜)λ0 (3),
• in which neff denotes an equivalent refractive index of the layers interposed between a first interface between the lower reflector and the first spacer layer and a second interface between the third spacer layer and the gap section,
• d denotes a distance between the first interface and the second interface,
• ma denotes an integer of 2 or larger, and
• λ0 denotes a central wavelength of a reflection wavelength band of the upper reflector or the lower reflector,
• neff′ denotes an equivalent refractive index of at least a layer disposed between the second interface and a third interface between the second spacer layer and the central non-oxidized region,
• du denotes a distance between the second interface and the third interface,
• mb denotes an integer of 0 or larger, and
• λ0 denotes the central wavelength of the reflection wavelength band of the upper reflector or the lower reflector.