Photon-number squeezing by the nonlinear backward pump process in a constant-voltage heterojunction LED

Abstract

We investigated extensively the sub-Poissonian-photon-state generation by the microscopic backward-pump (BP) process in a semiconductor heterojunction light-emitting diode (LED) under constant-voltage operation. In particular, the BP rate relative to the forward pump rate has been carefully evaluated from the dc characteristics of the LED and shown to depend strongly on the injection current and the device temperature. We then compare the experimental results of the photon-number squeezing performed at various temperatures in the constant-voltage-drive setup with the theoretical prediction estimated numerically using the parameter values determined from the dc measurements. As a consequence, it was proven that the observed squeezing at room temperature is successfully interpreted only in terms of the nonlinear BP model, while that at low temperature $(\ensuremath{\sim}100 \mathrm{K})$ is explained simply by the conventional model based on macroscopic Coulomb-blockade effect for the pump-noise suppression.