A fraction of the fundamental beam energy deposited into nonlinear crystals to generate second harmonic waves (SHW) causes a temperature gradient within the crystal. This temperature inhomogeneity can alter the refractive index of the medium leading to a well-known effect called thermal dispersion. Therefore, the generated SHW suffers from thermal lensing and a longitudinal thermal phase mismatching. In this work by coupling the heat equation with second harmonic generation (SHG) formalism applied to type-II configuration along with walk-off effect, we investigate the continuous wave (CW) SHW beam profile and conversion efficiency when a non-linear KTP crystal is under induced thermal load. We have demonstrated for average and high powers, the thermal de-phasing lead to considerable reduction in SHG compared to an ideal case in which induced heat is neglected.

In this work, the effects of size and wetting layer (WL) on subband electronic envelop functions, eigenenergies, linear and nonlinear absorption coefficients, and refractive indices of a dome-shaped InAs/GaAs quantum dot (QD) were investigated. In our model, a dome of InAs QD with its WL embedded in a GaAs matrix was considered. A finite height barrier potential at the InAs/GaAs interface was assumed. To calculate envelope functions and eigenenergies, the effective one-electronic-band Hamiltonian and electron effective mass approximation were used. The linear and nonlinear optical properties were calculated by the density matrix formalism.

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Knowledge about the temperature distribution inside solid-state laser crystals is essential for calculation of thermal phase shift, thermal lensing, thermally induced birefringence, and heat-induced crystal bending. Solutions for the temperature distribution for the case of steady-state heat loading have appeared in the literature only for simple cylindrical crystal shapes and are usually based on numerical techniques. For the first time, to our knowledge, a full analytical solution of the heat equation for an anisotropic cubic cross-section solid-state crystal is presented. The crystal is assumed to be longitudinally pumped by a Gaussian pump profile. The pump power attenuation along the crystal and the real cooling mechanisms, such as convection, are considered in detail. A comparison between our analytical solutions and its numerical counterparts shows excellent agreement when just a few terms are employed in the series solutions.