Optical Bistability in a GaAs-Based Polariton Diode

We report on a new type of optical nonlinearity in a polariton $p\mathrm{\text{−}}i\mathrm{\text{−}}n$ microcavity. Abrupt switching between the strong and weak coupling regime is induced by controlling the electric field within the cavity. As a consequence, bistable cycles are observed for low optical powers (2–3 orders of magnitude less than for Kerr induced bistability). Signatures of switching fronts propagating through the whole $300\times 300\mu {\mathrm{m}}^2$ mesa surface are evidenced.

Figure 1

(a) Schematic sample structure. (b) Photocurrent as a function of the laser energy measured with an optical power $P=10\mathrm{W}/{\mathrm{cm}}^2$ and for different voltage bias. Spectra have been vertically shifted for clarity.

Figure 2

(a) and (b) experimental (black) and simulated (green) photocurrent as a function of the excitation power for to values of the bias. (c) Photocurrent as a function of excitation power for $V_B=0.22\mathrm{V}$. (d) and (e) Differential photocurrent spectra measured for $V_B=0.22\mathrm{V}$ with a chopped probe ($P_{\mathrm{probe}}\sim 5\mathrm{W}/{\mathrm{cm}}^2$), (d) $P=0$ and (e) $P=25\mathrm{W}/{\mathrm{cm}}^2$. (f) Experimental (full symbols) and simulated (open symbols) pump powers for the $\mathrm{SC}\to \mathrm{WC}$ and $\mathrm{WC}\to \mathrm{SC}$. (g) and (h) photocurrent measured varying the bias at fixed excitation power.

Figure 3

Real space image (in logarithmic color scale) of the pump spot reflected on the sample surface. $V_B=-2\mathrm{V}$ and $P_{\mathrm{pump}}\sim 2\mathrm{kW}/{\mathrm{cm}}^2$ setting the system in the bistable region. (a) the sample is in WC regime; (b) similar than (a) but with the writing laser beam shone in region 1: the whole surface has switched into the WC regime; (c) reflected intensities averaged on region 1, 2 and 3 during the sequence indicated on top.