Room-temperature quantum light sources

方伟 教授
2018-07-20 (周五) 14:00

Two ways of generating room-temperature quantum light sources will be presented in this talk: correlated photon-pair generation based on four-wave mixing from long micro/nanofiber and electrically-driven single-photon sources based on colloidal quantum dots.
Micro/nanofiber (MNF) has large refractive index contrast between the fiber and the cladding air, so that it can confine the light to sub-wavelength dimension. Thus the MNF exhibits much larger nonlinearity than that from ordinary single-mode fiber or photonic crystal fiber. The MNF demonstrated was drawn from a standard single mode fiber by flame brush method, with a uniform diameter around 760 nm and a length of 12 cm. A pico-second pulsed laser was launched into the MNF as pump source, and photon-counting measurements yielded a coincidence-to-accidental ratio of 530 for the generated correlated photon-pairs.
The electrically-driven single-photon sources based on CdSe/CdS core/shell colloidal quantum dot were fabricated by solution process. The device consists of isolated quantum dots embedded in a PMMA layer between the hole-transport and electron-transport layers. When a voltage 2.6 V was applied on the device, the second-order temporal correlation function (g(2)(t)) was measured smaller than 0.05 at zero delay without any spectral filtering or background correction, which indicated the generation of high-purity single photons.