Simultaneous determination of nonlinear optical and thermo-optic parameters of liquid samples

Abstract

The authors apply the theory of photothermal lens formation and also that of pure optical nonlinearity to account for the phase modulation in a beam as it traverses a nonlinear medium. It is used to simultaneously determine the nonlinear optical refraction and the thermo-optic coefficient. They demonstrate this technique using some metal phthalocyanines dissolved in dimethyl sulfoxide, irradiated by a Q-switched Nd:YAG laser with 10 Hz repetition rate and a pulse width of 8 ns. The mechanism for reverse saturable absorption in these materials is also discussed.

Time-resolved study electronic and thermal contributions to the nonlinear refractive index of Nd3+:SBN laser crystals

“…K is the thermal conductivity, j is the fraction of excitation photon energy that is converted into heat, and ds/dT is the temperature coefficient of the optical path length change. Unlike liquid samples where we take into account only the temperature coefficient of the refractive index variation, dn/dT [11], in solid ones we have to consider ds/dT, which involves dn/ dT, thermal expansion, and optical stress caused by the heating of the sample [6]. The TL temporal signal evolution depends on the characteristic response time, which is given by…”

Nonlinear absorption study in four and five energy level systems

“…Experimentally researchers have seen the four and five energy levels participation in the degenerate absorption process [9][10][11][12][13][14][15][16][17][18][19][20]. But still, no article has discussed absorption cross-sections and lifetimes effect in the nonlinear absorption process.…”