INTENSITY FLUCTUATION SPECTROSCOPY OF SMALL NUMBERS OF DYE MOLECULES IN A MICROCAVITY

The spontaneous emission from a thin layer of a dilute solution of flu orescent dye molecules within an optical microcavity has been studied. Strong fluctuations in fluorescence intensity are observed when the a verage number of molecules in the measurement volume is small. We have performed experiments that simultaneously characterize these fluctuat ions over nine orders of magnitude of time, from ns to s. These measur ements have identified photon antibunching characteristic of single-mo lecule emission, along with triplet-state shelving and diffusion drive n number fluctuations. The results give fundamental information on the kinetics of dye molecules and allow one to speculate about the prospe ct of using single molecules as sources of single photons for quantum optics.