Journal ArticleRoom temperature terahertz quantum cascade laser sources with 215  <i>μ</i> W output power through epilayer-down mountingLu, Q Y; Bandyopadhyay, N; Slivken, S; Bai, Y; Razeghi, M<p>We report room temperature terahertz (THz) quantum cascade laser sources with high power based on difference frequency generation. The device is Čerenkov phase matched and spectrally purified with an integrated dual-period distributed-feedback grating. Symmetric current injection and epilayer-down mounting of the device onto a patterned submount are used to improve the electrical uniformity and heat removal, respectively. The epilayer-down mounting also allows for THz anti-reflective coating to enhance the THz outcoupling efficiency. Single mode emission at 3.5 THz with a side-mode suppression ratio and output power up to 30 dB and 215 μW are obtained, respectively.</p>AIP Publishing2013-07-0110596459Applied Physics Letters10310003-6951https://doi.org/10.1063/1.48128142149908National Science Foundation