Photocurrent readout and electro-optical tuning of resonantly excited exciton polaritons in a trap

We discuss a technique to manipulate and read out strictly resonantly excited exciton polaritons confined in a three-dimensional trap. The polaritons are trapped via their photonic part in a locally elongated microcavity with a high quality factor (Q ~ 6000), giving rise to sharp zero-dimensional resonances. Manipulation of the polaritons is achieved by spectrally tuning the quantum well excitons via the quantum confined Stark effect up to 10 meV, while the signal of the resonantly excited polaritons is simultaneously read out via the photocurrent flowing through the device. The effects of polariton-polariton interactions and interactions with the environment are revealed in the zero detuning regime by excitation power dependent investigations. By increasing the polariton number in our trap via resonant optical injection, we observe a pronounced blueshift of the lower polariton eigenenergy towards the weakly coupled cavity resonance. Furthermore, the photocurrent exhibits pronounced nonlinearities when self-tuned into resonance via its excitation dependent spectral blueshift.