Absorption and Fluorescence

R. W. WOOD

Stephen H. Ashworth

John Burke

J. Y. P. Butter, Bert Hecht, Brent R. Crenshaw +1 more

Simultaneous detection of single molecules by absorption and fluorescence is demonstrated using confocal microscopy at cryogenic temperature. Dynamical processes such as blinking and spectral jumping of single emitters are observed in both detection channels. The relative magnitude of fluorescence and absorption varies between molecules. In particular, we observe molecules that do not emit detectable Stokes-shifted fluorescence but show a strong absorption signal. The fact that coherent resonant scattering underlies the absorption process is demonstrated by a correlation between small linewidth and large absorption amplitude.

John Kellock Robertson

A. Saı̈ssy, Zhijia Cai, Daniel B. Ostrowsky

We report the study of absorption and fluorescence in neodymium doped silica fibers with excitation pulses much shorter than the fluorescence lifetime. Fluorescence and absorption saturation are observed for pump powers well below the damage threshold of the fiber. The saturation process is described using the density matrix method for the light absorption and the normal mode formalism for the propagation. The experimental results are in good agreement with the theory.