Exciton-polariton integrated circuits

We show that logical signals encoded in bistable states in semiconductor microcavities can be generated and controlled electronically by exploiting the electrical sensitivity of Tamm-plasmon–exciton-polariton modes. The signals can be transported along polariton neurons, created with a patterned metal surface. Using the Gross-Pitaevskii equations, we simulate an electrically controlled transistor and find that high repetition rates (10 GHz) are possible.

Figure 1

(Color online) (a) Schematic diagram of a semiconductor microcavity with metallic electrodes used to realize an electrically controlled polariton neuron. A strip of metal on the surface is divided into four segments, which are individually connected to an electrical supply (not shown) allowing the polariton potential to be changed in each segment. Note that the diagram is not to scale; in reality the lateral size of the metal strip is larger than the height of the structure. (b) Dependence of the polariton density on the optical pump intensity for different values of the detuning $\left({\Delta }_1<{\Delta }_0<{\Delta }_2\right)$ between the optical pump photon energy and the lower polariton energy. The detuning can be changed in the different segments by varying the applied electric potential. For a pump intensity close to the vertical gray line, switching between the different curves can have a major effect on the polariton density. (c) Dispersion relation for cavity polaritons (blue dashed curve) and hybrid TPEPM (green solid curve). The lowest-energy hybrid state is redshifted by several meV with respect to the lowest polariton mode in the vicinity of metal overlay, providing localization of exciton-polaritons in the channels below the metallic segments. (d) Redshift of the ground TPEP modes (solid curve) and exciton modes (dashed curve).

Figure 2

(Color online) Response of the polariton intensity in the microcavity plane when the potential in the first segment is altered such that the pump-polariton detuning is changed from ${\Delta }_0=0.5\text{meV}$ to ${\Delta }_1=0.4\text{meV}$. Initially the intensity in the first segment increases. Polaritons then propagate into the second region where there is a switching to the higher intensity state allowed by bistability. The polariton signal continues to a distance limited by the extent of the optical pump (which has a $40\mu \text{m}$ half-width at half-maximum in the $x$ direction in the calculation).

Figure 3

(Color online) The same situation as in Fig. 2 but a potential is also applied to the third segment, such that the pump-polariton detuning there is ${\Delta }_2=0.8\text{meV}$, and blocks the signal propagation along the polariton neuron.