Room-Temperature Polariton Laser

Abstract

In this presentation, the main drawbacks of GaN based microcavities (MCs) are first pointed out. Achieving high quality factor MCs is a tough task because of intrinsic material properties like the lattice mismatch existing between GaN and AlN. To circumvent this issue, a different strategy based on lattice-matched AlInN alloy is adopted. Although difficult to grow, AlInN epitaxial layers can be successfully implemented to make high reflectivity distributed Bragg reflectors, and subsequently, high quality factor MCs. AlInN based MCs exhibit photonic disorder but record quality factor in excess of 6000 has been measured. Combining these MCs to low linewidth GaN QWs demonstrate SCR at 300 K with a Rabi splitting of 56 meV, the largest value reported so far for inorganic MCs. Optical pumping experiments performed on GaN bulk MCs have already shown the potential of III-V nitride semiconductors for polariton lasing. Recent results obtained on QW-MC indicate very low threshold lasing and polariton condensation in the lower polariton branch well. This is accompanied by the appearance of spontaneous linear polarization. The threshold is dependent on the detuning of the cavity mode with respect to the exciton mode. Finally, preliminary results obtained on electrical injection in these MC structures are presented.