Determination of Dispersion Relation and Optical Parameters Induced by Exciton–Polariton Effect in Whispering-Gallery Microcavities Using Photoluminescence Spectroscopy

Abstract

To realize the refractive index dispersion accurately is essential for the design of optical devices. In this paper, we study hexagonal ZnO microrod cavities. We measure angle-resolved photoluminescence and use an iterative method to derive the refractive index dispersion near the band edge. Because of the large exciton binding energy in bulk ZnO, the photogenerated excitons are stable at room temperature. As a result, excitons could significantly affect the refractive index dispersion near the resonance energy. Thus, we construct a modified Lorentz oscillator model to extract the transverse and longitudinal exciton resonance energy and the damping term due to the scattering between LO-phonons and excitons at room temperature. The Rabi splitting energy and zero detuning point obtained by this method are reliable. The dispersion relations of polaritons measured by our angle-resolved photoluminescence agree well with the dispersion relation of polaritons, deduced by using the refractive index dispersion and optical parameters obtained by our theoretical model, thus, lending support to our theoretical model and the extracted parameters.

Super-Broad-Wavelength-Range Polarization-Selective Exciton-Polariton in Sn-Doped CdS Nanowires

“…In the fixed radius nanowires, the mode energy difference between different modes decreases with the increase of angle when the Sn-doped CdS nanowires are parallel to the entrance slit of the monochromator. According to previous studies, these two emission peaks come from different polarization modes of the microcavity . If the energy difference between the TE mode and TM mode is small, the coupling behavior is more obvious, which is shown by the large modulation of their energy momentum dispersion, that is, the anticrossing between two polarization modes.…”

“…According to previous studies, these two emission peaks come from different polarization modes of the microcavity. 47 If the energy difference between the TE mode and TM mode is small, the coupling behavior is more obvious, which is shown by the large modulation of their energy momentum dispersion, that is, the anticrossing between two polarization modes. Therefore, our experiment provides evidence of TE mode and TM mode coupling.…”

Ultraviolet Exciton-Polariton Light-Emitting Diode in a ZnO Microwire Homojunction

“…This unnatural increase of group index suggests that a strong exciton-photon coupling interaction would occur in the p-ZnO:Sb MW/n-ZnO homojunction LED, further confirming the exciton-polariton quasi-particle features. 59,62 The exciton-polariton dispersion in k ⃗ space was calculated, and the corresponding energy-wavevector dispersion curves in the x-y plane (in the cross section of ZnO:Sb MW) of as-constructed p-ZnO:Sb MW/n-ZnO homojunction LED are illustrated in Figure 5d according to Equation 5. The upper polariton (UP) and lower polariton (LP) branches were formed as a result of coherent oscillation between the cavity photon state and the exciton state.…”

Exciton–polariton light-emitting diode based on a single ZnO superlattice microwire heterojunction with performance enhanced by Rh nanostructures

“…The exciton–polariton effect should be included for proper understanding of the PL spectra of a single ZnO/ZnO:Ga superlattice MW. 35,38,61…”

“…The exciton-polariton effect should be included for proper understanding of the PL spectra of a single ZnO/ZnO:Ga superlattice MW. 35,38,61 To clearly understand the coupling interaction between confined excitons and photons in the axial ZnO/ZnO:Ga superlattice MW cavity, the energy-wavevector (E-k) dispersion was calculated according to the coupled oscillator model: 62,63 Eðo; kÞ ¼ ho ¼ hck ffiffiffiffiffiffiffiffiffiffiffiffiffiffi eðo; kÞ p…”