Optical device having self-hermetic coating and method of fabricating the same

An optical device, comprising:

• a semiconductor stack structure, configured to generate a laser beam when receiving a current, and emit the laser beam from a front facet of the semiconductor stack structure, wherein the front facet is a lateral side of the semiconductor stack structure;
• an anti-reflective film, disposed on the front facet, and configured to increase of the transmittance of the laser beam;
• and
• a highly-reflective film, disposed on a rear facet of the semiconductor stack structure, wherein the rear facet is another lateral side of the semiconductor stack structure, and the highly-reflective film is configured to reduce a loss of the laser beam transmitted to the rear facet,
• wherein, the anti-reflective film and the highly-reflective film each comprises a plurality of first dielectric films and at least one second dielectric film disposed alternately, wherein the plurality of first dielectric films and the second dielectric film have different refractive indices, and the refractive indices of the plurality of first dielectric films and the second dielectric film are greater than about 1.4.