Fig. 3: Quantitative analysis of the coherent and incoherent dynamics in the QCL.
From: Field-resolved high-order sub-cycle nonlinearities in a terahertz semiconductor laser
a Back-transformed electric field corresponding to the pump-probe signal \(E_{{{{\mathrm{PP}}}}_1}\). b Slice through \(E_{{{{\mathrm{PP}}}}_1}\)(t, τ) at a delay time t = 1.0 ps (see black dashed line in a). Blue dashed line: numerical fit of function A1 exp(−τ⁄Tgr)+C. c Gain recovery time Tgr of the QCL as a function of the bias current, extracted from the PP1 signal (red dots) and the full nonlinear time domain signal (gray). The error bars display the uncertainty of the numerical fit. Light blue dashed line: Tgr as a function of the pump rate G, extracted from the rate equation model. d Back-transformed electric field corresponding to the four-wave mixing signal \(E_{4{{{\mathrm{WM}}}}_1}\). e Slice through \(E_{4{{{\mathrm{WM}}}}_1}\)(t, τ) at an example delay time t = 1.0 ps (see black dashed line in d). Blue dashed line: numerical fit of function \(A_2\sin \left( {2\pi \nu_{{{\mathrm{L}}}}\tau + \phi} \right)\exp \left( { - \frac{\tau }{{T_2}}} \right)\). f Decay time of the coherent population T2 as a function of the bias current. The error displays the uncertainty of T2 for different delay times between 0.45 and 1.75 ps
