Design of unipolar intersubband lasers for terahertz emission

Design results are presented for quantum cascade lasers (QCLs) of either GaN-based or Si-based system. The n–i–n GaN/AlGaN QCL offers the advantage of room temperature operation, while the p–i–p SiGe/Si QCLs offer the potential for monolithic integration of Si photonics with Si electronics. Population dynamics analysis shows that both systems are capable of reaching sufficient optical gain for lasing at wavelengths in the tetrahertz range.