Coupled spatial multimode solitons in microcavity wires

Abstract

A modal expansion approach is developed and employed to investigate and elucidate the nonlinear mechanism behind the multistability and formation of coupled multi-mode polariton solitons in microcavity wires. With pump switched on and realistic dissipation parameters, truncating the expansion up to the second-order wire mode, our model predicts two distinct coupled soliton branches: stable and ustable. Modulational stability of the homogeneous solution and soliton branches stability are studied. Our simplified 1D model is in remarkably good agreement with the full 2D mean-field Gross-Pitaevskii model, reproducing correctly the soliton existence domain upon variation of pump amplitude and the onset of multistability.

Simulation of nonlinear polariton dynamics in microcavity wires for polaritonic integrated circuits

“…The multi-mode solitons deserve special attention, since they are capable of propagating further along an imperfect microcavity than their single-mode counterparts. We have developed a modal expansion method [5] to investigate the nonlinear mechanisms behind localisation, and attempt to find a means to leverage the inter-modal interactions for the development of polaritonic integrated circuits.…”

The impact of microcavity wire width on polariton soliton existence and multistability

“…After the transient soliton formation process, the FWHM of the soliton peak taken in the x direction is not constant, but changes by no more than 30% by the time it reaches the end facet of the wire. The driving force behind this FWHM variation is currently unclear; however, this will be a subject of further investigation using our newly developed coupled-mode expansion technique [16].…”

“…The normalisation is such that g E ), normalised with respect to the Rabi frequency. The reference frequency is blue-shifted with respect to the resonance frequency of the lower polariton branch for a given angle of incidence of the pump; the blue-shift is important because only then is excitation of a bistable mode possible over a finite range of E p [16]. c…”

“…Although at this stage we cannot comment on a plausible origin of this, it would be interesting to investigate the nature of this correlation in the future. In order to explain quantitatively this peculiar non-monotonous behaviour, we have recently developed a coupled-mode expansion method [16]. A detailed analysis using this method will be presented in a forthcoming paper.…”

“…Self-localisation phenomena in multi-mode systems arise due to counter-balancing nonlinearity with a combination of dispersive effects: material (polariton) dispersion due to a frequency-dependent dielectric response, cavity modes dispersion, and variation of the group velocity of each mode. In a recent work [16], using the coupled-mode expansion technique we showed that a new component of the nonlinearity has to be taken into account-namely, the intermodal nonlinear coupling. The latter arises from two distinct nonlinear phenomena: intermodal cross-phase modulation (through Kerr nonlinearity) and degenerate four-wave mixing (through polariton parametric scattering).…”