Thermal lens formation study in Chlorophyll compound using CW laser

Abstract

In this research, the thermal lens technique was used to study the thermal effect and the nonlinear optical phenomena of chlorophyll dissolved in a chloroform. The measurements were performed using a high-power continuous wave laser with a wavelength of 532 nm, and another low-power laser (Helium - Neon) used as a probe laser with wavelength of 632.8 nm.

The thermal lens signals were recorded as function of the input pumping powers; the experimental results have shown that at high input pump powers, the curve shape of the signal changes to what is called the “inflection point phenomenon”. The experimental values of the thermal lens signals were fitted using a mathematical model in order to calculate a number of optical parameters such as: the photo-thermal coefficient (dn/dT), the nonlinear refractive index (n₂) and the thermal diffusivity (D).Then, the evolution time of thermal lens formation was studied. Our experimental results have shown the possibility of using the chlorophyll as optical modulator in the optoelectronic devices in the future.