High efficiency beam combination of 4.6-\mu m quantum cascade lasers

The quantum cascade laser (QCL), a potential laser source for mid-infrared applications, has all of the advantages of a semiconductor laser, such as small volume and light weight, and is driven by electric power.However, the optical power of a single QCL is limited by serious self-heating effects.Therefore, beam combination technology is essential to achieve higher laser powers.In this letter, we demonstrate a simple beam combination scheme using two QCLs to extend the output peak power of the lasers to 2.3 W. A high beam combination efficiency of 89% and beam quality factor of less than 5 are also achieved.