Theory of sub-10 fs-generation in Kerr-lens mode-locked solid-state lasers with a coherent semiconductor absorber

Abstract

The results of the study of ultra-short pulse generation in continuous-wave Kerr-lens mode-locked (KLM) solid-state lasers with semiconductor saturable absorbers are presented. The issues of extremely short pulse generation are addressed in the frames of the theory that accounts for the coherent nature of the absorber-pulse interaction. We developed an analytical model that bases on the coupled generalized Landau-Ginzburg laser equation and Bloch equations for coherent absorber. We showed, that in the absence of KLM semiconductor absorber produces 2it-non-soliton pulses of self-induced transparency, while the KLM provides an extremely short soliton generation. 2it-and itsech-shaped soliton solutions and variablesquared chirped solutions have been found. It was shown, that the presence of KLM loosens the stability requirements for ultra-short pulse generation removing the limitation on the minimal modulation depth in absorber necessary for the pulse stabilization. An automudulation stability and self-starting ability analysis is presented.

Nonlinear dynamics of spatial and temporal patterns in lasers and atom optics: Kerr-lens mode-locked laser, Zeeman laser and Bose-Einstein atomic condensate

“…ОР course, there exists the exponential factor appearing from Laguerre-Gaussian modes, but it has no influence on singular points. This 2D vector field can be associated with the autonomous dynamical system: й й x=X(x(), (1), y=Y(x( 2), (1)), (18) and the classification оё the KL-mode polarization pattern can be made investigating the character of the singular points (zeroes оЁ X апа Y ) оЁ this system. There are three possibilities [49]:…”

“…The Schrédinger equation for the field envelope was completed with gain, losses, high-order dispersion terms [16,17], Bloch equations for the coherent semiconductor absorber [18], stimulated Raman gain [19] and then either solved numerically or evaluated analytically using the hyperbolic secant ansatz for the solution [14, 3,4]. This allows one to estimate the pulse chirp, pulse width and stability conditions.…”

Interactions of chirped femtosecond soliton-like pulses

“…As is well-known, the symmetry of the soliton will be destroyed when one of the high-order effects, such as third-order dispersion, nonlinear dispersion, nonlinear gradient term and nonlinear absorption etc, acts separately. But the balance between them can keep the shape of soliton, this has been verified both experimentally [12,13] and theoretically. [11,14−16] For an optical system, including bandwidth-limited gain and higher order effects, a so-called distributed model can be used when the period of the perturbation is small in comparison with the amplifiers spacing.…”