Quantum cascade lasers with discrete and non equidistant extended tuning tailored by simulated annealing.

In this work, we report a new superstructure grating design method for broad, non-equidistant discrete tuning in quantum cascade lasers using the Vernier effect. Our approach is applied to a wafer with gain centred at ∼7.8 μm. Measurements of a 3.75 mm long device are presented yielding 3.66% tuning around the central frequency and a peak optical power over 200 mW at 0 ∘C heat sink temperature. In addition, we show that taking into account the optical dispersion of the material is crucial to fulfill narrow specifications. Our device is particularly well suited for multi absorption line spectroscopic measurements requiring high resolution and small form factor for high volume production.