Strong light–matter interaction in ZnO microcavities

Abstract

The strong light-matter interaction in ZnO-embedded microcavities has received great attention in recent years, due to its ability to generate the robust bosonic quasiparticles, exciton-polaritons, at or above room temperature. This review introduces the strong coupling effect in ZnO-based microcavities and describes the recent progress in this field. In addition, the report contains a systematic analysis of the room-temperature strong-coupling effects from relaxation to polariton lasing. The stable room temperature operation of polaritonic effects in a ZnO microcavity promises a wide range of practical applications in the future, such as ultra-low power consumption coherent light emitters in the ultraviolet region, polaritonic transport, and other fundamental of quantum optics in solid-state systems. Keywords: microcavity; polariton; strong coupling; ZnO INTRODUCTIONOver the past two decades, strong light-matter interactions in solidstate systems have garnered much attention for applications in novel photonics devices. The polariton is the key factor in the strong coupling phenomena: a new bosonic quasiparticle that is a hybrid between matter and light and exhibits promise for investigating various fascinating effects including dynamical Bose condensation, 1-4 superfluidity 5,6 and quantized vortices. 7-10 Semiconductor microcavities (MCs), which simultaneously offer good optical confinement with a small mode volume for the photonics portion and an excitonic layer for the matter portion of the strong coupling, are regarded as promising candidates for demonstrating and manipulating strong light-matter coupling in solid-state systems. 11 Because the semiconductor MCs undergo a strong coupling regime, the coupling rate between the bared exciton modes and the confined photon modes is faster than their dissipation rates. Compared with weakly coupled MCs, the rapid exchange rate in strongly coupled MCs renders the energy transfer between the excitons and photons reversible and reduces the possibility of energy dissipation through non-radiative channels, which results in a higher internal quantum efficiency. The new eigenstates generated from the strong exciton-photon coupling are called exciton-polaritons 12 and exhibit a relatively small effective mass compared with atomic hydrogen, tunable dispersion curves, and the bosonic statistics at low densities.Given the aforementioned properties, many phenomena have been extensively studied in polariton systems, including ultra-low threshold polariton lasing, 13 polariton parametric oscillation 14-17 and polaritonic circuits. 18 The matter characteristic of the polaritons allows them to scatter with electrons, phonons and polaritons, then to condense in the coherent ground state. The laser-like light emission from a coherent polariton ground state, the so-called polariton laser, does not require the population inversion condition required by conventional

Electrically driven plasmon mediated energy transfer between ZnO microwires and Au nanoparticles

“…4). The d band energy levels lie 2.4 eV below the Fermi energy levels for Au, making interband excitations considerably more unlikely than intraband excitations 13,15,19,21,50 . Fig.…”

Whispering‐gallery mode lasing in ZnO microcavities

“…An ultralow threshold lasing is expected in the exciton–polariton system based on its bosonic property. In recent years, the lasing with ultralow threshold has been observed at room temperature and claimed as exciton–polariton by various groups . However, some different opinions on the phenomena and mechanism have also been presented, for example, Versteegh et al.…”

Polariton condensation phase diagram in wide-band-gap planar microcavities: GaN versus ZnO

“…On the contrary, the robustness of excitons in GaN and ZnO at RT has led to an increasing interest for these materials, especially after the first observation at RT of the strong coupling regime (SCR) 23 , and of polariton lasing in bulk- 24 and quantum well-based 25 GaN MCs elaborated on sapphire substrates. Concerning ZnO MCs, the SCR at RT has been reported more recently [26][27][28][29] , followed by polariton lasing at 120K 30 , then up to 250 K 31 , and finally at RT 32,33 . The difficulty to increase the number of pairs of the distributed Bragg reflectors (DBRs) due to the lattice and thermal expansion coefficient mismatch between silicon and nitrides prevented the achievement of polariton lasing in such samples 34,35 .…”