Design and analysis of high-performance terahertz quantum cascade lasers

We propose a new design for a high-performance terahertz (THz) quantum cascade laser (QCL) and investigate the characteristics of the laser by using rate equation analysis. By comparing the four-level system in our design with the three-level system in the conventional THz QCL, it was found that both a lower threshold current and higher slope efficiency can be realized in the former. Furthermore, it was found that the four-level system has higher operating temperature tolerance. These results are expected to contribute to the development of THz QCLs that can be operated at high temperatures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)