Enhanced properties of the mid-infrared superluminescent emitter with a composite waveguide

This study reports on a composite structure composing tilted taper, and tilted and curved waveguides with the aim of enhancing the spectral width and output power of mid-infrared quantum cascade superluminescent emitters (QC-SLEs). The computational results indicate that a tilt angle of 10° and a curved angle of 20° can avoid the selectivity of a certain wavelength due to interference effects at tilt angles of 6° and 8°, resulting in the minimum reflectivity of 1.3×10^-4 and 4.4×10^-4 for each wide and narrow cavity surface. Simultaneously, the modes propagating perpendicular to the cavity surface exist the least. The corresponding experimental results show a significant enhancement in the spectral width to 168.5c m ^-1 and a high power output of 5.1 mW for the device. This study presents what we believe to be a novel concept for the designing of superluminescent emitters with both a broadband and high power output.