Propagation of single-cycle terahertz pulses in random media

We describe what are to our knowledge the first measurements of the propagation of coherent, single-cycle pulses of terahertz radiation in a scattering medium. By measuring the transmission as a function of the length L of the medium, we extract the scattering mean free path l(s)(omega) over abroad bandwidth. We observe variations in l(s) ranging over nearly 2 orders of magnitude and covering the entire thin sample regime from L/l(s) much less than 1 to L/l(s) similar to 10. We also observe scattering-induced dispersive effects, which can be attributed to the additional path traveled by photons scattered at small angles. (C) 2001 Optical Society of America.