Control of mode-locking efficiency in a Kerr-lens mode-locked Ti:sapphire laser

Multipulse operation and limits of the Kerr-lens mode-locking stability

“…This generic scheme is suitable to model practically all the published experimental studies of multipulsing in Kerr-lens mode-locked lasers in different active media [1], [13], [14], [19], [20], [22], [23], [26]. While our main interest stays with the case of the Cr:ZnSe laser [26], we also consider the Kerr-lens mode-locked Ti:Sapphire laser to verify our model.…”

“…While our main interest stays with the case of the Cr:ZnSe laser [26], we also consider the Kerr-lens mode-locked Ti:Sapphire laser to verify our model. For the latter, we take the well-documented experiment in [13] for modeling. It is also important that for both experiments the setup parameters are available in every detail.…”

“…The slowly decaying exponential wings corresponds to the "bounded" perturbations, which increase as a result of the approach to the stability boundary (transition from the dash-dotted to the solid curve). As the increase of the pulse intensity saturates the fast absorber, its discrimination strength decreases [13], thus favoring the perturbation growth and the pulse dissociation (dotted curve). The described picture agrees qualitatively with the analytical analysis presented in [45], where the complex amplitude of the perturbation is proportional to the pulse energy and the parameter of the saturation of the self-amplitude modulation.…”

“…In the calculation, we took into account only the first term in the expansion on in the last term of (10) (dashed curve in Fig. 9(a); this treatment is similar to that for the explanation of the colliding-pulses regime in [13], where the double-pulse generation resulted from the stronger Kerr lensing for the colliding pulses). The combination with the spectral filtering can lead to the "absorption" of the pulses into the "potential well" for the comparatively small and (dotted curve in Fig.…”

“…The presence of the continuous local (i.e., through the pulse wings) interaction between the pulses distinguishes such bounded soliton-like complexes from the regimes created as a result of the repetition-rate multiplication due to the change of the gain and loss saturation balance in the system [10]- [12]. One should also distinguish the stable multipulse operation from the generation of the double pulses colliding in an active medium [13]- [16]. It should be noted that the transition to multipulse operation is not the sole scenario of the stability loss in the continuous-wave (CW) mode-locked solid-state lasers: the automodulational instability can produce regular as well as nonregular oscillations of the single pulse or the so-called picosecond collapse with the abrupt transition from the femtosecond to the picosecond generation [17], [18].…”