Output characteristics of distributed feedback 3.0 terahertz quantum cascade lasers.

Distributed feedback quantum cascade lasers lased at 3.0 THz were prepared and their output performance was analyzed. The optimized grating parameters were obtained by theoretical analyses. Single-mode emission was obtained and a maximum output power of more than 166 mW at 15 K was achieved. The corresponding threshold current density was 257/ , and the side-mode suppression ratio was more than 15 dB. By changing the input voltage, the frequency was stable with a variation of less than 3 GHz. A beam with obviously fast and slow axis features was observed. Further improvement and the potential application of distributed feedback quantum cascade lasers are discussed.