High repetition rate femtosecond lasers able to deliver pulse energies ranging from few hundred microjoules to the millijoule level is a very active and competitive field in laser research. In laser bulk technology, major improvements toward high average power were (i) the reduction of the pump heat load through Yb-doped crystals development and (ii) the availability of low cost and bright diode-laser pump sources. Nodaways, Yb:YAG laser sources provide few hundreds of watts at multi-kHz repetition rates in thin disk or slab amplifier configurations with pulse duration close to the picosecond level due to the restricted gain bandwidth of Yb:YAG. Shortening the pulse duration of high average power laser, without the help of self-phase modulation process inside or outside the amplifier, requires Yb-doped crystal hosts associating broad gain bandwidth and good thermal conductivity. So far, Yb-doped regenerative amplifiers delivering multi-watt at multi-kHz repetition rate provide pulse duration close to 300 fs in Yb:CALGO and 200 fs in Yb:CaF 2 at cryogenic temperature. In this work, we report on the first 130 fs room temperature Yb:CaF 2 chirped pulse regenerative amplifier delivering an average power exceeding 4.3 watts when the laser system operates from 5 kHz to 50 kHz. By means of an Yb-doped fiber pump source, a long Yb:CaF 2 crystal with low doping concentration has been used to increase the heat load volume and therefore reduce the amplifier temperature while maintaining high optical efficiency and broad effective bandwidth emission.
We report the development of a compact diode-pumped Terawatt laser dedicated to intense mJ-level Terahertz generation. It delivers 220mJ at 50Hz with 415fs pulse duration and a Strehl ratio exceeding 0,98.
By means of a high-brightness optical pumping scheme with a fiber laser, we demonstrate Kerr-lens mode locking (KLM) with an Yb:CaF2 laser crystal. Stable 48 fs pulses are produced at an average power of 2.7 W.
Get PDF Email Share Share with Facebook Share on X Post on reddit Share with LinkedIn Add to Mendeley Add to BibSonomy Share with WeChat Get Citation Copy Citation Text P. Sevillano, P. Camy, J. L. Doualan, R. Moncorgé, D. Descamps, and E. Cormier, "130fs – Multiwatt Yb:CaF2 regenerative amplifier pumped by a fiber laser," in Lasers Congress 2016 (ASSL, LSC, LAC), OSA Technical Digest (online) (Optica Publishing Group, 2016), paper ATh4A.5. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article
High power high energy lasers have recently emerged as potential solution for several applications such as secondary rays generation, nuclear fusion and medical therapy. One major limitation of such systems for high energy extraction is the laser-induced damage threshold (LIDT) of laser components. In this context, many studies have been devoted to the determination of the LIDT of laser materials under certain operational conditions and the identification of the limiting factors at the nanoseconds and femto/sub-picoseconds regime 1–3.However, these measurements do not consider that in most high intensity laser chains such as chirped pulsed amplification (CPA), pulses are stretched to larger duration such as hundreds of picoseconds. Thus, measuring the LIDT of laser materials under stretched pulses irradiation becomes critical. In this work, we report a study of the influence of the coating treatment and fatigue in the LIDT of Yb:YAG crystals under stretched pulses by means of 1-on-1, Rasterscan and S-on-1 tests. We use a 1mJ, 1kHz laser (S-Pulse model from Amplitude Systèmes) modified to support 150 ps-pulse duration. We show a lower LIDT of the AR-coating compared to that of the HR-coating (7J/cm2) and preliminary outcomes point out a non-deterministic effect of the fatigue at this regime of pulse duration. These results show the importance of testing critical components at hundred-picoseconds regime for high power and high energy lasers. 1. Sozet, M. et al. Laser damage density measurement of optical components in the sub-picosecond regime. 40, 2–5 (2015). 2. Smith, A. V & Do, B. T. Bulk and surface laser damage of silica by picosecond and nanosecond pulses at 1064 nm. (2008). 3. Jensen, L. O. et al. Investigations on SiO 2 / HfO 2 mixtures for nanosecond and femtosecond pulses a Laser. 7842, 1–10 (2017).
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.
We report on Kerr lens mode locking (KLM) of Yb:CALGO by means of high-brightness optical pumping with a diffraction limited fibre laser. Various cavity configurations (intracavity group delay dispersion and output coupler transmission) have been investigated to deliver sub-40 fs pulses at watt level and pulse duration as short as 32 fs.
By means of a diffraction limited pump source delivering 40 W at 976 nm, we demonstrate a broadband booster amplifier operating at 96 MHz based on a 29 mm Yb:CaF2 crystal. Without any stretching, pulses as short as 70 fs have been amplified up to 16.5 W in a single-pass configuration corresponding to an optical efficiently of 34 % and an optical gain of 5.7.
