Room-temperature long-wavelength (λ=13.3μm) unipolar quantum dot intersubband laser

Long-wavelength (lambda = 13.3 mu m) unipolar lasing at 283 K from self-organised In0.4Ga0.6As/GaAs quantum dots. due to intersubband transitions in the conduction band, is demonstrated for the first time. The threshold current density under continuous wave operation is 1.1 kA/cm(2) for a 60 mu m x 1.2 mm broad-area plasmon-enhanced waveguide device and the maximum power output is similar or equal to 1 mu W. The longs intersubband relaxation time in quantum dots, together with the short lifetime in the ground state, due to interband stimulated emission. help to achieve the necessary population inversion and gain.