Tailoring a coherent control solution landscape by linear transforms of spectral phase basis

Abstract

Abstract:Finding an optimal phase pattern in a multidimensional solution landscape becomes easier and faster if local optima are suppressed and contour lines are tailored towards closed convex patterns. Using wideband second harmonic generation as a coherent control test case, we show that a linear combination of spectral phase basis functions can result in such improvements and also in separable phase terms, each of which can be found independently. The improved shapes are attributed to a suppressed nonlinear shear, changing the relative orientation of contour lines. The first order approximation of the process shows a simple relation between input and output phase profiles, useful for pulse shaping at ultraviolet wavelengths.

Investigation of adaptive laser pulse shaping by direct estimation of group delay profile

“…Given the insufficient knowledge about the complex underlying dynamics and/or the control mechanism in many practical optimizations, pulse shaping is commonly implemented using an adaptive scheme [4][5][6][7][8]. Despite successful demonstration of the phasesensitive nature of many light-matter interactions using adaptive schemes, efficient implementations of optimization algorithms in such experiments and the extraction of (even qualitative) insight from the "optimal" phase profiles are still key challenges [9][10][11][12].…”

Tailoring pulses for coherent Raman microscopy

“…The patterns associated with similar-parity orders feature a reduced symmetry, compared to quasi-symmetric patterns of oppositeparity orders. These symmetries are very similar to the 2D polynomial landscapes of second harmonic generation [68,71].…”

“…Replacing the spectral phase basis of a coherent control experiment with appropriate linear combinations of the basis functions can result in a new landscape with more convex contours, less shear, and even separable phase terms [68,71]. This technique can also be used successfully in the case of a CARS experiment.…”

“…However, note that this transform is a shear and not a rotation of contour lines. This is why the apparent ellipticity of the contour lines has changed [68].…”

“…Ideally, the contour lines are convex, connected (no local optima), and without nonlinear shear (relative rotation) [68].…”