We consider the free carrier dispersion effect in a semiconductor nanocavity in the limit of discrete photoexcited electron-hole pairs. This analysis reveals the possibility of ultrafast, incoherent transduction and gain from a single photon signal to a strong coherent probe field. Homodyne detection of the displaced probe field enables a new method for room temperature, photon-number-resolving single photon detection. In particular, we estimate that a single photon absorbed within a silicon nanocavity can, within tens of picoseconds, be detected with ∼99% efficiency and a dark count rate on the order of kHz assuming a mode volume Veff∼10−2(λ/nSi)3 for a 4.5 micron probe wavelength and a loaded quality factor Q on the order of 104.
@article{arxiv.1812.07176,
title = {Single Photon Detection by Cavity-Assisted All-Optical Gain},
author = {Christopher Panuski and Mihir Pant and Mikkel Heuck and Ryan Hamerly and Dirk Englund},
journal= {arXiv preprint arXiv:1812.07176},
year = {2019}
}