Backscattering Suppression in Supersonic 1D Polariton Condensates

We investigate the effect of disorder on the propagation of one-dimensional polariton condensates in semiconductor microcavities. We observe a strong suppression of the backscattering produced by the imperfections of the structure when increasing the condensate density. This suppression occurs in the supersonic regime and is simultaneous to the onset of parametric instabilities which enable the “hopping” of the condensate through the disorder. Our results evidence a new mechanism for the strong scattering reduction of polaritons at high speeds.

Figure 1

(a) Scanning electron microscope image of the wire and scheme of the experiment. (b)–(e) Normalized far field emission of the polariton gas in the probed region. (f) Energy and momentum of the polariton condensates at different excitation powers. The solid line shows the polariton dispersion and the inset the corresponding values of the group velocity.

Figure 2

(a) Emitted intensity in the probed region as a function of excitation power in units of threshold power $P_{\mathrm{th}}$ (7 mW). (b) Black points (red circles): Ratio of the backscattered [$I(-k)$] to the incident polariton signal [$I(+k)$] at the energy of the peak signal, experimentally (theoretically) obtained in the conditions of Fig. 1. Inset: Backscattered ratio measured at low excitation power (below the condensation threshold) as a function of the energy of the propagating polaritons.

Figure 3

(a) Schematic representation of the disorder potential showing the spatial extension of localized states (horizontal bars) and the parametrically induced hopping process. (b) Disorder potential used in the model. (c)–(e) Simulation of the polariton far field emission in the disordered potential with increasing polariton density. The upper-left squared region in (e) shows a magnification of the lower squared area.