Generation of sub-20-fs pulses from a graphene mode-locked laser

TL;DR

This paper reports the generation of the shortest solid-state laser pulses to date, achieving 19-fs duration using a graphene saturable absorber in a diode-pumped Cr3+:LiSAF laser, with stable operation and tunability.

Contribution

It demonstrates for the first time sub-20-fs pulses directly from a graphene mode-locked solid-state laser with detailed mode locking verification.

Findings

Generated 19-fs pulses at 850 nm

Achieved stable mode locking with graphene saturable absorber

Tunable pulse duration from 80 to 190 fs

Abstract

We demonstrate, what is to our knowledge, the shortest pulses directly generated to date from a solid-state laser, mode locked with a graphene saturable absorber (GSA). In the experiments, a low-threshold diode-pumped Cr3+:LiSAF laser was used near 850 nm. At a pump power of 275 mW provided by two pump diodes, the Cr3+:LiSAF laser produced nearly transform-limited, 19-fs pulses with an average output power of 8.5 mW. The repetition rate was around 107 MHz, corresponding to a pulse energy and peak power of 79 pJ and 4.2 kW, respectively. Once mode locking was initiated with the GSA, stable, uninterrupted femtosecond pulse generation could be obtained. In addition, the femtosecond output of the laser could be tuned from 836 nm to 897 nm with pulse durations in the range of 80-190 fs. We further performed detailed mode locking initiation tests across the full cavity stability range of the laser to verify that pulse generation was indeed started by the GSA and not by Kerr lens mode locking.