Coupled Nonlinear Optical Processes During Absorption by Manipulating the Induced Cubic Susceptibility

We present a theoretical study of the experimentally proved fact that, in perspective nonlinear materials with an absorption band in the tuning frequency range, two simultaneous three-wave processes are realized – optical parametric generation and generation of the second harmonic of an idler wave. The analysis is carried out, taking into account the depletion of the pump wave, the phase mismatch, and the losses of all interacting waves. These two three-wave processes can be phenomenologically described as an overall four-wave interaction of waves with a phase mismatch, which induces an effective third-order optical susceptibility in a nonlinear medium that exceeds the intrinsic third-order susceptibility of the medium. In the pump depletion regime, we give a more correct determination of the induced effective cubic susceptibility of a nonlinear medium and show that the effective cubic susceptibility depends on the intensities and coefficients of the nonlinear coupling of all interacting waves. Thus, by controlling the induced cubic susceptibility, it is possible to develop promising laser tunable sources through absorption bands in the UV and mid-IR spectral ranges.