New approach for the incoherent and coherent combination of pulsed lasers

TL;DR

This paper introduces a novel method for combining pulsed laser beams both coherently and incoherently, demonstrating that the combined intensity at the pulse peak remains consistent with continuous-wave modes, while allowing flexible laser arrangements.

Contribution

The work presents a new configuration that removes paraxial constraints and enables arbitrary spatial positioning of lasers in pulsed beam combination.

Findings

At pulse peak, combined intensity matches continuous-wave results.

Incoherent pulsed combination causes spatial thinning for pulses under 100 fs.

Filling factor does not affect secondary lobes or energy distribution.

Abstract

This work focuses on the incoherent and coherent combination of pulsed laser beams, building on previous research [1] that addressed the combination of continuous-wave laser beams. For the pulsed combination, we have focused on the temporal evolution of the combined intensity at the image plane. Simulation results show that at the pulse peak, the combined intensity profile is the same, whether in continuous-wave or pulsed mode, for both coherent and incoherent combinations. However, we observe spatial thinning of the combined beams in the case of incoherent pulsed combination when the pulse widths are less than 100 fs. At the front of the pulse, we observe lateral lobes near the focal point, which disappear as we approach the peak of the pulse. Similar to the continuous-wave laser beam combination, our simulations show that in both coherent and incoherent pulsed combinations, the filling factor has no impact on the formation of secondary lobes or on the proportion of energy in the central lobe. Furthermore, with the new configuration, we are no longer constrained by paraxial optics, as the number of lasers that can be combined is arbitrary, and their positions can be chosen freely in space.