Semiconductor light source free from facet reflections

摘要

A new class of optical source having a truncated waveguide is provided, where a guided section of a light generating medium is terminated at an angle at a predetermined distance away from one end facet of the waveguide, thereby leaving a section for unguided light propagation. A truncated waveguide when implemented in combination with waveguide tilt, effective front facet reflectivity is reduced significantly to eliminate unwanted facet reflections. By extending electrical pumping in the unguided propagation section, the light in the unguided path propagates to a corresponding end facet without attenuation. The reflected light propagates freely without being intercepted by the waveguide. The principles are incorporated in different types of light generating and amplifying medium including a “double-pass” gain medium for designing optical sources having significantly high output power and negligibly small spectral modulation arising from unwanted facet reflections.

主权项

1. A light source comprising:
a light generating medium having two ends terminating in corresponding end facets, said light generating medium further including; a waveguide having a first end disposed at an angle with respect to the normal to a first end facet, said first end of the waveguide is terminated at a predetermined distance prior to reaching said first end facet, said termination facilitated by terminating lateral confinement on both sides along the length of the waveguide, such that the light generated within the light generating medium, is laterally guided in the waveguide, and is substantially unguided without attenuation, between the first end of the waveguide and said first end facet; wherein, said angle and said predetermined distance are selected in prescribed combinations, such that only a small component of the light reflected from the first end facet is intercepted in the waveguide; and wherein a second opposite end of the waveguide is disposed at a corresponding second end facet in accordance with a pre-determined design, such that upon pumping the light generating medium, an optical path between the two end facets allows light to traverse in one or more passes through the waveguide, and exhibits optical gain in the light generating medium in the waveguide and in the region between the first end of the waveguide and said first end facet.