Super-luminescent diode and external cavity laser including the same

An external cavity laser comprising:

• an element substrate;
• a super-luminescent diode provided at one side of the element substrate;
• a mirror provided at another side of the element substrate;
• and
• an optical filter provided between the mirror and the super-luminescent diode,
• wherein the super-luminescent diode comprises:
• a substrate including a gain region, a window region spaced apart from the gain region, and a tapered region between the window region and the gain region;
• an active waveguide layer including a lower waveguide layer provided on the substrate and extending from the gain region to the window region, and an upper waveguide layer provided on the lower waveguide layer and extending from the gain region to the tapered region;
• and
• a clad layer provided on the lower waveguide layer and the upper waveguide layer of the active waveguide layer,
• wherein each of the lower waveguide layer and the upper waveguide layer comprises asymmetric separate confinement heterostructure (SCH) layers.

A super-luminescent diode manufacturing method comprising:

• providing a lower waveguide layer and an upper waveguide layer on a substrate including a gain region, a window region spaced apart from the gain region, and a tapered region between the gain region and the window region;
• removing a portion of the upper waveguide layer in the tapered region and the window region to taper the upper waveguide layer in the tapered region in one direction;
• and
• removing a portion of the upper waveguide layer in the gain region and a portion of the lower waveguide layer and the upper waveguide layer in the gain region, the tapered region, and the window region to taper the lower waveguide layer in a direction opposite to the tapering direction of the upper waveguide layer,
• wherein each of the upper waveguide layer and the lower waveguide layer comprises asymmetric SCH layers.