Ring quantum cascade lasers with grating phase shifts and a light collimating dielectric metamaterial for enhanced infrared spectroscopy

Brighter and more efficient light sources are desired to further increase the sensitivity of spectroscopic measurements. Simultaneously, a strong trend towards miniaturization and compactness is ubiquitous. In the last years quantum cascade lasers have become powerful and reliable tools for infrared spectroscopy. We report on ring quantum cascade lasers with two distinct features which increase the efficiency of these devices and provide enhanced performance for spectroscopic applications. First, the distributed feedback grating exhibits two Ϭ-phase shifts. This provides far fields with a central intensity maximum. Second, a gradient index metamaterial is fabricated into the substrate. This collimates the emitted light and can replace external optics.