High-Efficiency Beam Combination of Continuous-Wave Quantum Cascade Lasers

High-Power External Spatial Beam Combining of 7-Channel Quantum Cascade Lasers Emitting at ~8.5 μm

“…For the narrow ridge of a single QCL, the size of the transverse waveguide is nearly identical to that of the lateral waveguide, which causes a small astigmatism. Consequently, only a single circular aspheric lens can be used for the collimation of the fast and slow axis [22]. The adopted lasing wavelength of the QCL was about 8.5 μm, and the average output power of each single QCL was 500 mW.…”

“…For coherent beam combining, as the number of combining units increases, the conditions for achieving interference become more stringent, and the complexity of the system increases sharply [12,13]. The incoherent beam combining methods available for QCLs include polarization beam combining [14], waveguide beam combining [15,16], spectral beam combining [17,18], and spatial beam combining [19][20][21][22]. Most of these incoherent beam-combining schemes are costly and require the use of gratings, and are difficult to assemble.…”