Two-photon absorption and photon-number squeezing with CdSe nanocrystals

We have demonstrated the reduction of photon-number fluctuations below the shot-noise level (photon-number squeezing) by two-photon absorption in an inorganic semiconductor material consisting of a thin film of TOPO-decorated Use nanocrystals embedded in a PMMA polymer host. The photon-number squeezing was measured at 800 nm, where the linear absorption of the material was negligible. The amount of photon-number squeezing from the CdSe system was similar to5% for a moderate value of nonlinear transmission. This observation was possible due to the large nonlinear absorption exhibited by the system of CdSe NCs embedded in PMMA and also due to the reduced linear scattering losses in thin films. The CdSe squeezing data are compared to results previously obtained for the first time in a nonlinear optical polymeric material. The achievement of photon-number squeezing in these novel materials gives the opportunity for future application in the improvement of the signal-to-noise ratio in optical communications.