Temperature-dependent characteristics of a midinfrared quantum cascade laser (QCL) including the threshold current, the output power, the modulation bandwidth, and the relative intensity noise (RIN) exhibit a deterioration with temperature from 77 to 300 K. Based on a comprehensive temperature-dependent model we show that optical injection locking can be applied to surpass the intrinsically limited thermal characteristics of a QCL through the modification of the carrier density in the active region. A modulation bandwidth improvement of $\approx 35\%$ and an almost temperature-independent RIN behavior for an injection-locked laser have been achieved compared to a free-running slave laser at room temperature. A threshold current reduction of $\approx 20\%$ has also been obtained at 300 K. Results indicate that the locking boundaries of an injection-locked QCL are suppressed with temperature. The output power and the small-signal characteristics of the laser have also been analyzed in the entire stable locking range.

• Received 30 July 2019

DOI:https://doi.org/10.1103/PhysRevA.100.053856