grated gain model at a thickness of 75 A, the solid line shows logarithmic dependence, and the dashed line shows the dependence of degree 0.541.
The figure shows that the logarithmic model most exactly describes the calculation diagram.
An analysis of the quasi-Fermi level versus electron concentration and QW layer thickness has been presented. Is shown that, at a thickness less than 200 A, the thickness influences the curve steepness of the characteristic.
5. Conclusions
In this work, we have deduced the gain in the form g s ' Ε½ . G N r 1 q S using Bloch equations, and have compared expressions for the nonlinear parameters and . As a ws result, s r2. With important numerical research, the ws dynamic characteristics using single-mode rate equations are compared to two forms of gain nonlinearities, with and without a square root in a large-signal regime. The gain in the form with a square root agrees better with experimental results the rather large light power.
Thus, a calculation technique for modeling the carrier concentration influence on the quasi-Fermi level is proposed to calculate the peculiarities of the bulk and QW structures. A modified expression is given for the function of the total density of states versus energy that has enabled us to reduce the time of the numerical analysis. Numerical investigations have been realized, and the dependence of the quasi-Fermi levels on the conduction band of QW laser structures is reported for various thicknesses of the active layer. So, in this work, the original expression for the QW laser total density of states calculation is shown. This expression has allowed us to reduce the model calculation time.
During numerical analysis, the optical gain versus electron concentration at a thickness less than 200 A is shown, and the nonlinearity of this characteristic is observed. During comparative analysis, the expression that most exactly describes the calculation diagram is determined. This model is the logarithmic gain model.