title: Optical precursors and Beer's law violations; non-exponential propagation losses in water.
abstract: We develop a model for exponential decay of broadband pulses, and examine its implications for experiments on optical precursors. One of the signature features of Brillouin precursors is attenuation with a less rapid decay than that predicted by Beer's Law. Depending on the pulse parameters and the model that is adopted for the dielectric properties of the medium, the limiting z-dependence of the loss has been described as z1/2, z1/3, exponential, or, in more detailed descriptions, some combination of the above. Experimental results in the search for precursors are examined in light of the different models, and a stringent test for sub-exponential decay is applied to data on propagation of 500 femtosecond pulses through 1-5 meters of water.
authors.forename: Ursula
authors.initials: U
authors.lastname: Gibson
authors.forename: Ulf
authors.initials: U
authors.lastname: Osterberg