Theory of photon-number squeezing in a heterojunction LED by the nonlinear backward pump process

Abstract

We present a theoretical framework for sub-Poissonian-photon-state generation based on a microscopic backward-pump (BP) process in a semiconductor heterojunction light-emitting diode (LED). The model, which takes into account the BP and nonradiative recombination processes as well as the dynamical response of the external circuit, is applicable to practical LED's. It is shown that the nonlinear dependence of the BP rate on the carrier number in the active region brings about the photon-number squeezing below the full-shot-noise level, without recourse to a high-impedance constant-current source. We also point out that the bandwidth of the squeezing by the nonlinear BP process is wider than that limited by the recombination lifetime. In addition, we discuss the origin of the nonlinearity of the BP rate based on a microscopic model for the injected carriers in the active region. The nonlinearity is suggested to be due to the rises of the electron temperature and of energetic position of the quasi-Fermi level, with increasing pump current.