High-brightness fiber laser-pumped 68  fs–23  W Kerr-lens mode-locked Yb:CaF_2 oscillator

Abstract

By using a high-brightness fiber pump laser, we demonstrate a pure Kerr-lens mode-locked (ML) Yb:CaF(2) oscillator. The laser delivers 68 fs pulses with 2.3 W average power at 73 MHz repetition rate and an optical-to-optical efficiency of 33% is achieved. To the best of our knowledge, this is the first demonstration of Kerr-lens mode-locking in Yb:CaF(2). Incidentally, we report here the highest average power ever achieved for a sub-100-fs active Kerr-lens ML Yb-bulk oscillator.

Powerful 67 fs Kerr-lens mode-locked prismless Yb:KGW oscillator

“…In another recent KLM experiment, 2.3 W were produced from an Yb:CaF 2 laser with 75 fs pulses and extracavity compression down to 68 fs. This laser, however, was not directly diode-pumped and required a diffraction limited pump beam [22].…”

Diode-pumped ultrafast Yb:KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking

“…The generation of 68 fs and 48 fs pulses with output powers of 2.3 W and 2.7 W using the Kerr-lens mode locking have been reported in [12] and [10], respectively. It should be noted that results presented in [9,10] and [12] were not obtained with directly diodepumped lasers which greatly reduces their overall efficiency and potential for further power scaling. Therefore, the use of commercially available laser diodes for direct diode pumping is a desired feature due to the reduced cost and complexity of the laser system.…”

“…Another promising Yb-doped laser crystal for generating high power sub-100 fs pulses is Yb:CaF2 crystal with a thermal conductivity coefficient of 6 W/m/K and emission bandwidth of 30 nm [34,35]. The generation of 68 fs and 48 fs pulses with output powers of 2.3 W and 2.7 W using the Kerr-lens mode locking have been reported in [12] and [10], respectively. It should be noted that results presented in [9,10] and [12] were not obtained with directly diodepumped lasers which greatly reduces their overall efficiency and potential for further power scaling.…”

“…The Yb-ion based laser oscillators are well suited for this task. The generation of watt-level sub-100 femtosecond laser pulses directly from Yb-doped bulk crystal lasers has been reported for Yb:KGW [5][6][7], Yb:CALGO [8,9], Yb:CaF2 [10][11][12] and Yb 3+ :Lu2O3 [13] gain media. Such a performance of a mode-locked laser is feasible owing to the propitious properties of Yb-ion crystals, including a fairly broad gain bandwidth, absorption properties suitable for a diode pumping, an absence of parasitic losses and a tolerable level of thermo-optical effects [14][15][16].…”

Kerr-Lens Mode-Locked Femtosecond Yb:GdYSiO5 Laser Directly Pumped by a Laser Diode

“…In addition, the large lower-level splitting results in a broad emission bandwidth, which is beneficial to generate ultrashort pulses by various mode-locking techniques. Until now, a number of Yb 3+ -doped laser materials have been developed to generate femtosecond pulses [3][4][5][6][7]. The shortest pulse duration reported thus far was 32 fs in a Yb:CaGdAlO4 oscillator optically pumped by a fiber laser [8].…”