Nonlinear fundamental photothermal response in three-dimensional geometry: Theoretical model

Abstract

Theoretical and experimental aspects of three-dimensional infrared photothermal radiometry of semiconductors A general three-dimensional theoretical model for fundamental and harmonic response generation as a result of periodic heating of a system consisting of a nonlinear layer with temperature-dependent thermal conductivity and specific heat and a linear substrate is developed. Analysis of the fundamental component of the surface temperature shows that the nonlinear thermal conductivity alone does not affect the phase of the thermal-wave field. The efficiency of the thin nonlinear layer as an energy conversion filter that drives the harmonic response of the substrate is shown by the analysis of the limiting cases of the theoretical model.

Nonlinear photoacoustic response of opaque media in gas microphone signal detection

“…In the second case, δp 1N (ω) suppresses the linear component of the signal, while if we neglect thermal nonlinearity, K 1N = 1 and expression (19) becomes formula (27) from [1], obtained for thermally thick, opaque systems. Expressions (18) and (19) are the desired quantities and show that first of all, in the considered case, thermal nonlinearity does not affect the phase of the photoacoustic signal, which is consistent with the conclusion in [26], obtained when solving the nonlinear thermal wave problem in a laser radiation field for a constant absorption coefficient. Secondly, a trivial relationship exists between the amplitudes of the overall and nonlinear components of the photoacoustic signal and the thermal nonlinearity parameters of the thermophysical and optical quantities.…”

Double modulated thermoreflectance microscopy of semiconductor devices

“…In both cases, 2 f and 4 f detection, the signals from the surrounding mesa region are very weak, since possible higher harmonic thermal waves related, e.g., to the temperature dependence of the thermophysical properties, 17 are small in comparison to the coupling effects generated by the combined optical and electrical excitation.…”

Dynamic photothermal and thermoelastic microscopies described by complex finite element analysis

“…[1][2][3][4][5] Related analytical models have been developed in order to describe the generated thermal field. 2,4,6,7 As a matter of fact, most photothermal applications deal with two main topics: subsurface imaging [8][9][10] and thermal constants determination that require photothermal modeling. 1,8,9,11 The heat source generated by laser irradiation induces elastic deformations that yield surface displacement.…”