Sub-100-fs bulk solid-state lasers near 2-micron

SESAM mode-locked Tm:LuYO3 ceramic laser generating 54-fs pulses at 2048 nm

“…It demonstrates that a resonant-type SA can be equally good or even better for mode-locking of such femtosecond lasers. Whereas from previous studies it is known that such SESAMs typically show slower response, larger modulation depths and lower non-saturable losses compared to SWCNT-SAs [13], the present results indicate that these characteristic parameters are not of crucial importance and can vary in quite broad ranges, see Table 1 in [13]. Finally, we note that while Tm-fiber lasers have produced slightly shorter pulse durations, this was only the case after external compression in a prism pair [16] while the oscillator itself operated in the chirped pulse regime, delivering pulse durations of the order of 1 ps.…”

“…Such 2-μm SESAMs show a fast (few ps) absorption recovery time in particular for the nearsurface design [11] and an exceptionally broad reflection band of ~ 300 nm due to the use of lattice-matched GaSb/AlAsSb distributed Bragg reflectors (DBRs) [12]. Sub-100-fs pulse ML operation of Tm 3+ doped or Tm 3+ , Ho 3+ co-doped laser materials at ~2 μm using such SESAMs has already been demonstrated [13]. In this work, we focus on the study of the mixed Tm:LuYO 3 ceramic as an active medium in combination with a GaSb-based SESAM for ML operation.…”

High-power modelocked thin-disk oscillators as potential technology for high-rate material processing

“…In particular, materials with good thermal properties that remain high at high doping concentration, wide emission bandwidths, large emission and absorption cross-sections and pumping wavelengths compatible with high-power pumping are needed, and are challenging to find. Generally, finding such materials has gained significant attention in the last decade, but most research has so far focused on bulk laser modelocking with moderate power levels [ 94 ]. In the thin-disk geometry, most results in this wavelength region have only been achieved in cw operation and had not – until very recently – conclusively shown large potential.…”

“…So far, no ultrafast operation of a Tm-doped disk laser has been demonstrated. In the bulk geometry however, several Tm-doped materials have been explored in modelocked operation: for example sesquioxides, CALGO and MgWO 4 , demonstrating pulse durations in the sub-100 fs duration with few tens of mW to few hundreds mW output power [ 94 ]. Among these materials, sesquioxides and CALGO based lasers are potentially good candidates for ultrafast TDLs.…”

“…This latest progress shows that currently, Ho-doped materials appear to be the most promising for high-power ultrafast TDL operation, see Figure 5 . Too much Tm ions with respect to other potential Ho-doped materials for the thin-disk geometry, most ultrafast bulk oscillators were accomplished by codoping with Tm ions [ 94 ], which can then be diode-pumped via the Tm ions and broader bandwidths can be exploited as their single ion counterparts, reaching pulse durations as short as sub-50 fs with an average output power of 121 mW [ 107 ]. However, Tm, Ho codoping method adds an additional degree of freedom which is the ratio between the Tm and Ho ions, which strongly affects lasing operation and depends on the host material, and therefore needs more detailed investigation before being attempted in the more complex thin-disk geometry.…”