Signal statistics of laser light scattering

Jan Pefina

Jakub Zakrzewski, T. Dohnalik

Previous theoretical treatments of polarisation spectroscopy (forward scattering) are generalised so as to include laser temporal coherence effects. It is shown that for the general case it is impossible to describe the signal obtained in terms of birefringence and dichroism. The generalisation of the concept of the polarisability tensor is given together with the approximate expression for the signal in terms of it. The simple example of the J g =0 to J e =1 transition in the forward scattering experiment is discussed in detail. Comparison is made between the signal lineshapes obtained for the phase diffusion model and the chaotic field model. The necessity of taking into account the statistical properties of the laser light in the forward scattering (polarisation spectroscopy) experiment is pointed out.

S. Ya. Kilin

Tadashi Aoki, Katsumi Sakurai

Microscopic scattering processes are discussed for two structures of light incident on thermal particles. One is composed of two collinear light beams originating from different oscillating modes of a laser, and another is composed of two counter propagating beams originating from the same oscillating mode. A comparison of the cumulant expansions for the above two cases has allowed discerning which terms in the scattering structures led to the same statistical properties of the scattered photons. It is shown that, for the scattering of multimode-laser light, the statistical properties of scattered photons are not affected by the noncorrelating random phases of the incident laser fields but are the same as those in the case of single-mode laser light under practical scattering experiments. The factorial moments ${F}_{k}[=〈n(n\ensuremath{-}1)\ensuremath{\cdots}(n\ensuremath{-}k+1)〉]$ up to sixth order of the scattered photons were measured for various scattering situations including the above two cases, and they were found to support the theoretical results.

Manabu Yoshikawa, Norihito Suzuki, Tatsuro Suzuki

The photon counting statistics of light is studied, in which the various types of photon counting distribution can be represented by Nakagami'sm-distribution. To investigate this theoretical utility we have measured the photon counting distribution of laser light scattered by a very dilute solution in which non-Gaussian statistics appear. The comparison is also made by the factrial moment between the experimental value and theoretical one. The experimental distribution is in agreement with the theoretical distribution.

Hannes Risken