| Popis: |
Mixed light-matter nature of exciton-polaritons brings the rich physics of correlated systems, e.g. Bose-Einstein-like condensation, to an all-semiconductor platform with potential applications for generation of correlated and entangled photons. One strategy towards this goal is to engineer the polariton density of states by spatial confinement. In this way, one can create a discrete spectrum of polariton energies to control the scattering pathways in an optical parametric oscillator (OPO) configuration. We fabricated 3D-traps with quasi-equidistant energy levels and positioned them at the anti-nodes of a standing surface acoustic wave (SAW). The SAW modulates the energies of the trap as a whole up to one meV and allows to realize perfect energy and momentum matching. When we resonantly excited polaritons in the confined middle level of the trap with a CW-laser under an applied SAW, we observed two emission peaks on both energy sides of the pump, spaced equidistantly with respect to the excitation energy - a typical OPO signature. The observation of an OPO for the confined polaritons is an important step towards novel sources of entangled photons. Another significant aspect of this work is the dynamic control of the generation of correlated photons by the SAW amplitude, frequency and phase. |
