On the criteria for strong and weak polarization responses of ordered objects and systems

Abstract

Abstract. The fundamental system of criteria for strong and weak polarization responses of ordered objects and systems is considered. It is shown that the weak responses have important properties of linearity (proportionality) and additivity. As an example, the responses of magnetically ordered materials, optical crystals and ensembles of magnetic nanoparticles are considered. When scanning laser probing of the modified leucosapphire crystals, oscillations of weak polarization responses in laser radiation scattered on texture of crystals are recorded. Investigations of magnetic fluids polarization responses have shown their high sensitivity to introduction of coagulating impurities and to processes of agglomeration of magnetic nanoparticles.

Weak polarization-optical responses of diluted magnetic nanofluid probed by laser radiation with polarization modulation

“…In a number of practical cases it is important to investigate samples with small optical anisotropy [16][17][18][19]. Our proposed natural criterion for the smallness of anisotropy is based on the inequality ∆ 1 rad [14]. When it is so, sin ∆ ∼ ∆ and the dependence ϕ(∆) becomes linear.…”

“…min.) [13,14,19,20]. In practice, the minimum value of the recorded response can often be limited, for example, by fluctuations of the laser radiation parameters used and other instrumental factors, which requires careful organization of the measuring procedure [17,18,21].…”

“…Nonstationary laser polarization-optical probing in the original combination with a differential photodetection scheme allows one to achieve a very high sensitivity of optical measurements up to a threshold that is limited only by natural (quantum, photonic) noise of radiation [13][14][15]. Earlier, by the methodology developed on this basis, we investigated the polarization characteristics of various objects, including optical elements with a high degree of optical and structural homogeneity [16], magnetically ordered materials [17], and perfect optical crystals, including those with a modified crystal structure [15].…”