Iteratively seeded mode-locking

TL;DR

This paper introduces an iteratively seeded mode-locking technique that overcomes fundamental performance limits in ultrashort pulsed lasers, significantly increasing pulse energy and offering broad applicability.

Contribution

The authors propose and numerically demonstrate an iteratively seeded mode-locking method that surpasses traditional performance limits in ultrashort pulsed lasers.

Findings

Achieved a five-fold increase in pulse energy with the new method.

Identified a performance limit related to the laser's seeding process, not the solution stability.

The approach can be integrated into existing laser systems without major modifications.

Abstract

Ultrashort pulsed mode-locked lasers enable research at new time-scales and revolutionary technologies from bioimaging to materials processing. In general, the performance of these lasers is determined by the degree to which the pulses of a particular resonator can be scaled in energy and pulse duration before destabilizing. To date, milestones have come from the application of more tolerant pulse solutions, drawing on nonlinear concepts like soliton formation and self-similarity. Despite these advances, lasers have not reached the predicted performance limits anticipated by these new solutions. In this letter, towards resolving this discrepancy, we demonstrate that the route by which the laser arrives at the solution presents a limit to performance which, moreover, is reached before the solution itself becomes unstable. In contrast to known self-starting limitations stemming from suboptimal saturable absorption, we show that this limit persists even with an ideal saturable absorber. Furthermore, we demonstrate that this limit can be completely surmounted with an iteratively seeded technique for mode-locking. Iteratively seeded mode-locking is numerically explored and compared to traditional static seeding, initially achieving a five-fold increase in energy. This approach is broadly applicable to mode-locked lasers and can be readily implemented into existing experimental architectures.