Time resolved propagation of ultrashort laser pulses within turbid tissues.

The time resolved propagation of femtosecond and picosecond laser pulses within turbid tissues is simulated by a Monte Carlo model. The internal distribution of irradiance for an impulse vs a 4-ps pulse is specified at different times for various scattering coefficients and scattering phase functions. Such simulations provide time resolved dosimetry for predicting the distribution of single-and two-photon chemical reactions in turbid tissues. For femtosecond pulses in highly scattering tissues, two-photon reactions are dominated by the initial primary (unscattered, unabsorbed) pulse, and single-photon reactions are dominated by the scattered diffuse irradiance. For picosecond pulses in highly scattering tissues, both single- and two-photon reactions are dominated by the scattered irradiance.