Quantum dimensionality, entropy, and the modulation response of quantum dot lasers

Rate equations are used to show that the modulation response of quantum dot lasers can be limited by entropy change due to carrier relaxation from a wetting layer. The entropy change is due to the difference in the spectral density of quantum states between the two-dimensional wetting layer and the zero-dimensional quantum dot. When limited by this effect, the laser’s 3 dB modulation response becomes strongly temperature dependent.