Thermo-optical parameters, including the refractive index temperature coefficient (d<i>n</i>/d<i>T</i>) and the absolute non-radiative quantum efficiency (Φ), were determined in solutions of a natural dye using a method based on thermally driven self-phase modulation (SPM) effects. The ring-pattern response to SPM effects was determined for annatto extracts obtained from the seeds of the tropical shrub <i>Bixa orellana L</i>. This approach determined the linear behavior of the ring numbers (<i>n</i>) observed in the far-field region as a function of excitation laser power (<i>P</i><sub>e</sub>). Thermo-optical characterizations of bixin (C<sub>25</sub>H<sub>30</sub>O<sub>4</sub>) solutions extracted using three solvents (toluene, chloroform, and acetone) were performed. The Φ results are in good experimental agreement with those obtained using the thermal lens (TL) technique. Values obtained for thermal diffusivity parameters were typical for pure solvents.
ADALBERTO N. IWAZAKI, VIVIANE. PILLA, VANESSA M. DIAS, EGBERTO. MUNIN, and ACÁCIO A. ANDRADE, "Self-Induced Phase Modulation for Thermo-Optical Characterization of Annatto Extracted Using Different Solvents," Appl. Spectrosc. 65, 1393-1397 (2011)