QD lasers go to market

摘要

Combining smaller threshold current density, temperature dependence and linewidth together with increased differential efficiency and power output, quantum dot lasers can now surpass quantum well lasers, extending lasing on GaAs substrates to 1.3 and 1.55 μm fibre-optic communications wavelengths to replace more costly InP-based lasers. In a bulk three-dimensional semiconductor, eg. a double heterostructure (DH) laser, interactions between closely packed atoms in the crystal lattice spread the energy levels of free electron and hole charge carriers into a continuous spectrum. Transitions due to the stimulated recombination of electron-hole pairs between conduction and valence bands result in light emission over a broad spread of wavelengths.