Folded cavity surface emitting laser

Abstract

A semiconductor laser diode comprising a light emitting diode, a polyhedral prism waveguide, and a single or multilayered partial-reflecting mirror. The polyhedral prism waveguide and the partial-reflecting mirror are located on opposite sides of the light emitting diode. A polyhedral prism waveguide increases modal discrimination within semiconductor laser diode's optical-feedback providing cavity by using total internal reflection to redirect intra-cavity produced light from a longitudinal propagation into a first transverse propagation, into a second transverse propagation, into a third transverse propagation, and then back into a longitudinal, but reversed propagation. The polyhedral prism waveguide, by effectively extending the cavity length of a vertically orientated laser diode, introduces diffraction loss to undesired higher-orders of transverse optical-moded light occurring within the laser, which in turn introduces increased gain to desired fundamental lower-order transverse optical-moded light also occurring within the laser. Consequently, selection of desired fundamental lower-order transverse optical-moded light over undesired higher-orders of transverse optical-moded light for amplification into coherent laser emission is accomplished.