Room-temperature Polariton Lasers Research Articles

Electrical polarization switching of perovskite polariton laser

Abstract Optoelectronic and spinoptronic technologies benefit from flexible and tunable coherent light sources combining the best properties of nano- and material-engineering to achieve favorable properties such as chiral lasing and low threshold nonlinearities. In this work we demonstrate an electrically wavelength- and polarization-tunable room temperature polariton laser due to emerging photonic spin–orbit coupling. For this purpose, we design an optical cavity filled with both birefringent nematic liquid crystal and an inorganic perovskite. Our versatile growth method of single CsPbBr3 inorganic perovskite crystals in polymer templates allows us to reach strong light–matter coupling and pump-induced condensation of exciton–polaritons resulting in coherent emission of light. The sensitivity of the liquid crystal to external voltage permits electrical tuning of the condensate energy across 7 nm; its threshold power, allowing us to electrically switch it on and off; and its state of polarization sweeping from linear to locally tilted circularly polarized emission.

Low-threshold polariton lasing in a highly disordered conjugated polymer

Low-threshold, room-temperature polariton lasing is crucial for future application of polaritonic devices. Conjugated polymers are attractive candidates for room-temperature polariton lasers, due to their high exciton binding energy, very high oscillator strength, easy fabrication, and tunability. However, to date, polariton lasing has only been reported in one conjugated polymer, ladder-type MeLPPP, whose very rigid structure gives an atypically narrow excitonic linewidth. Here, we observe polariton lasing in a highly disordered prototypical conjugated polymer, poly(9,9-dioctylfluorene), thereby opening up the field of polymer materials for polaritonics. The long-range spatial coherence of the emission shows a maximum fringe visibility contrast of 72%. The observed polariton lasing threshold (27.7 μJ/cm2, corresponding to an absorbed pump fluence of 19.1 μJ/cm2) is an order of magnitude smaller than for the previous polymer polariton laser, potentially bringing electrical pumping of such devices a step closer.

Polariton laser based on a ZnO photonic crystal slab

We propose a scheme of a ZnO room-temperature polariton laser based on a photonic crystal slab. We predict a very low threshold density for optical pumping: 5 × 1016 cm−3. We have studied the threshold dependence on the parameters of the system, such as detuning. The main advantage of photonic-crystal-based polariton laser is expected to be the simplicity of production.

Tailoring the strong coupling regime in III‐nitride based microcavities for room temperature polariton laser applications

AbstractWe report on the properties of III‐nitride based microcavities (MCs) operating in the strong coupling regime (SCR) up to room temperature. We first discuss why this class of materials is well suited to investigate the physics of cavity polaritons, which are admixed particles resulting from the coupling between cavity photons and excitons. In addition to the high quality of the different building blocks forming the MC, we point out the role of the active medium geometry, and in particular, the impact of the quantum well number and the distribution of the latter to maximize the vacuum Rabi splitting. Thanks to a well grounded SCR at high temperatures, we demonstrate polariton lasing in the 180‐340 K range whose threshold is mainly governed by thermally activated detrapping mechanisms. Since the trap depth formed by the lower polariton branch is fixed by the exciton‐cavity photon detuning (δ), it is shown that the polariton escape rate from the trap and hence the threshold power density strongly depend on this parameter. Experimental results are well accounted for when using a simplified thermodynamic model that reproduces the threshold behavior as a function of δ in the temperature range investigated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A polariton laser

Polaritons — particles comprising both light and matter — can form a coherent state, just as light and matter can individually. This fact has now been exploited to make the first room-temperature polariton laser.

Room-temperature polariton laser, intensity-controlled optical delays, subwavelength spatial pulse control, single-atom single-photon source, and more

Room-temperature polariton laser, intensity-controlled optical delays, subwavelength spatial pulse control, single-atom single-photon source, and more

Withdrawal: ZnO as a material mostly adapted for realisation of room-temperature polariton lasers [phys. stat. sol. (a)192, 212 (2002), phys. stat. sol. (a)195, 563 (2003)

The authors withdraw their articles published in phys. stat. sol. (a) 192, 212 (2002) and phys. stat. sol. (a) 195, 563 (2003). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

ZnO as a material mostly adapted for realization of room-temperature polariton lasers

ZnO as a material mostly adapted for realization of room-temperature polariton lasers

Room-temperature polariton lasers based on GaN microcavities

The critical temperature for Bose condensation of exciton polaritons in an AlGaN microcavity containing 9 GaN quantum wells is calculated to be T=460 K. We have modeled the kinetics of polaritons in such a microcavity device using the two-dimensional Boltzmann equation. Room-temperature lasing is found with a threshold as small as 100 mW. The kinetic blocking of polariton relaxation that prevents formation of the Bose-condensed phase of polaritons at low temperatures disappears at high temperatures, especially in n-doped samples. Thus, GaN microcavities are excellent candidates for realization of room-temperature polariton lasers.

ZnO as a Material Mostly Adapted for Realisation of Room-Temperature Polariton Lasers

Wannier-Mott excitons in the wurzite-type semiconductor material ZnO are stable at room temperature, have an extremely large oscillator strength and emit purple light. This makes ZnO an excellent potential candidate for the fabrication of room-temperature lasers where the coherent light amplification is ruled by the fascinating mechanism of the Bose-condensation of the exciton-polaritons. We first report on the direct optical measurement of the exciton oscillator strength f in ZnO. The longitudinal transverse splitting of the exciton resonances Γ 5 (B) and Γ 1 (C) are found to achieve record values of 5 and 7 meV, respectively, that is two orders of magnitude larger than that in GaAs. Secondly, we propose a model ZnO-based microcavity structure that is found to be the most adapted structure for the observation of the polariton laser effect. We thus can compute the phase diagram of the lasing regimes. A record value of the threshold power of 2 mW per device (at power density of 3000 W/cm 2 ) at room temperature is found for the model laser structure.

ZnO as a material mostly adapted for realisation of room-temperature polariton lasers

ZnO as a material mostly adapted for realisation of room-temperature polariton lasers

ZnO as a material mostly adapted for the realization of room-temperature polariton lasers

Wannier-Mott excitons in the wurzite-type semiconductor material ZnO are stable at room temperature, have an extremely large oscillator strength, and emit blue light. This makes ZnO an excellent potential candidate for the fabrication of room-temperature lasers where the coherent light amplification is ruled by the fascinating mechanism of the Bose condensation of the exciton polaritons. We report the direct optical measurement of the exciton oscillator strength f in ZnO. The longitudinal transverse splitting of the exciton resonances Γ 5 (B) and Γ 1 (C) are found to achieve record values of 5 and 7 meV, respectively, that, is two orders of magnitude larger than in GaAs. Second, we propose a model ZnO-based microcavity structure that is found to be the most adapted structure for the observation of the polariton laser effect. We thus can compute the phase diagram of the lasing regimes. A record value of the threshold power of 2 mW per device (at power density of 3000 W/cm 2 ) at room temperature is found for the model laser structure.