Quantum Interband and Cascade Lasers

Over 16 years have passed since the Bell Labs group headed by Federico Capasso first demonstrated the quantum cascade laser (QCL). The intervening interval has seen the QCL evolve from a barely functional scientific curiosity into a powerful technology poised to offer new capabilities to a broad spectrum of real-world applications. In assembling this special section of Optical Engineering, the dual goals have been to provide a snapshot of the cascade laser field in its adolescence, and to familiarise a wider audience of optical engineers with the far-reaching practical potential of these unique IR sources.