Light Matter Interaction Effects in III-V and II-VI Quantum Dot Micreresonators

Engineering the interaction of light with matter allows one to tune important properties of solids like e.g. the spontaneous emission rate or the spontaneous emission coupling factor into a laser mode. We have investigated light matter interaction effects in semiconductors using (QD) micropillar cavities and micro disks containing dots with strongly varying oscillator strength and different Q-factors in lll-V and ll-VI systems. Due to the three dimensional electronic confinement the quantum dot excitons act as the solid state equivalent of atom-like emitters. The three dimensional optical confinement in the cavities results in discrete photon modes. The energies of the QD excitons can be tuned in and out of resonance with the optical modes by temperature tuning. In the experiments on weak and strong coupling great care is taken to populate the cavity with only a single photon generated by the dot on resonance. This can be demonstrated nicely by studies of photon correlations for a quantum dot exciton in the strong coupling regime. Due to improvements in epitaxy and patterning technology it has been possible to further increase the Q factors of the micropillar cavities. We obtain Q values up to 160.000 for 4 mum diameter cavities, which decrease approximately linearly with the pillar diameter. The values for the vacuum Rabis splitting vary from about 140 mueV to about 20 mueV, when the oscillator strength of the InGaAs dots decreases from 50 to 10. Much larger values of the vacuum Rabi splitting are observed in ll-VI microrings with embedded dots, where the strongly increased oscillator strength of the ll-VI dots results in splittings of about 0.7 meV.