Strong normal-incidence infrared absorption in self-organized InAs/InAlAs quantum dots grown on InP(001)

International audienceInAs self-assembled quantum dots in InAlAs matrix grown on InP001 substrates have been fabricated using Stranski-Krastanov growth mode. A strong in-plane polarized intraband absorption in the 10.6-20 m wavelength region has been observed and ascribed to a transition from the ground electron state to an excited state confined in the layer plane along the 110 direction. The absorption at normal-incidence reaches 7.8% for ten layers of n-doped quantum dots. The oscillator strength of the intraband transition is comparable to that achieved in quantum wells for a conduction band intersubband transition. The dependence of the intraband absorption on carrier concentration and temperature suggests a quantum-wire type confinement potential

Mesoscopic self-collimation and slow light in all-positive index layered photonic crystals

We demonstrate a mesoscopic self-collimation effect in photonic crystal superlattices consisting of a periodic set of all-positive index 2D photonic crystal and homogeneous layers. We develop an electromagnetic theory showing that diffraction-free beams are observed when the curvature of the optical dispersion relation is properly compensated for. This approach allows to combine slow light regime together with self-collimation in photonic crystal superlattices presenting an extremely low filling ratio in air.Comment: 4 pages, 4 figure

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