Power scaling in quantum cascade lasers using broad-area stripes with reduced cascade number

Abstract

For many applications, optical emission power of many watts in the midinfrared part of the optical spectrum is required. Quantum cascade lasers for these applications typically contain 30 to 40 cascades and have laser ridge widths of about 10 μm. These lasers cannot, however, be readily scaled up in power. This paper demonstrates a path for further power scaling that is based on broad stripes with fewer than 15 cascades. Although the confinement factor Γ for this design approach is lower than for designs with 30 to 40 cascades, the ability to efficiently extract heat from the top and bottom of the lasers more than offsets the Γ disadvantage. We expect this approach to deliver tens of watts of power with high beam quality leading to high brilliance. The paper discusses the design approach, thermal conduction considerations, and confinement factor. Room temperature cw operation of broad-area lasers based on this approach is demonstrated and described.