Broadband high energy diode pumped Yb:KYW multipass amplifier

International audienceWe report a diode pumped Yb:KYW amplifier delivering up to 27 mJ pulses at a repetition rate of 100 Hz and a spectral bandwidth of 5.5 nm, centered at around 1030 nm. The system is based on a double-head multipass amplifier configuration where the pump thermal load is distributed over two relatively thin laser crystals which permits a sufficiently large number of passes with minimal passive losses thus maximizing the energy extraction efficiency. The amplified pulse bandwidth theoretically supports 340 fs pulses and as a demonstration, a small fraction of the amplified pulses has been compressed to 560 fs

High-contrast Ultrabroadband Frontend Source for High Intensity Few-Cycle Lasers

An ultrabroadband seed source for high-power, high-contrast OPCPA systems at 800 nm is presented. The source is based on post compression in a hollow-core fiber followed by crossed polarized waves (XPW) filtering and is capable of delivering 80$\mu$J, 5fs, CEP-stable (0.3rad RMS) pulses with excellent spectral and temporal qualit

High peak-power stretcher-free femtosecond fiber amplifier using passive spatio-temporal coherent combining

International audienceWe report on the passive coherent combining of up to 8 temporally and spatially separated ultrashort pulses amplified in a stretcher-free ytterbium-doped fiber system. An initial femtosecond pulse is split into 4 temporal replicas using divided-pulse amplification, and subsequently divided in two counter-propagating beams in a Sagnac interferometer containing a fiber amplifier. The spatio-temporal distribution of the peak-power inside the amplifier allows the generation of record 3.1 µJ and 50 fs pulses at 1 MHz of repetition rate with 52 MW of peak-power from a stretcher-free fiber amplifier and without additional nonlinear post-compression stages

Compact, simple and robust cross polarized wave generation source of few-cycle, high-contrast pulses for seeding petawatt-class laser systems

International audienceA compact and robust, dual-crystal cross polarized wave generation setup combined with a hollow waveguide filter is implemented to deliver few-cycle, high-contrast laser pulses sourced from a commercial multipass Ti:Sa amplifier. The initial 25-fs pulses with a temporal contrast of 108 are shortened to 10 fs with an improved contrast of at least 10^10. The single nonlinear stage for spectral broadening and contrast enhancement of a commercial amplifier serves as an ideal injector for petawatt-class laser systems

Temporal cleaning of a high energy fiber-based ultrafast laser using cross-polarized wave generation

International audienceWe report the use of cross-polarized wave generation to perform both pulse shortening and temporal cleaning of a high-energy ytterbium-doped fiber-based femtosecond laser system. The nonlinear processes allow both a highly efficient nonlinear conversion of 20% and a large compression ratio of 3.5, with inherently improved coherent and incoherent contrasts. This results in the generation of 37 μJ, 115 fs pulses at a repetition rate of 100 kHz with high temporal quality

Passive coherent combining of CEP-stable few-cycles pulses from a temporally divided hollow fiber compressor

International audienceWe demonstrate a simple and robust passive coherent combining technique for temporal compression of millijouleenergy laser pulses down to few-cycle duration in a gas-filled hollow fiber. High combining efficiency is achieved byusing carefully oriented calcite plates for temporal pulse division and recombination. Carrier-envelope phase (CEP)-stable, 6-fs, 800-nm pulses with more than 0.6 mJ energy are routinely generated. This method could aid in theenergy scaling of CEP-stable hollow-fiber compressor systems

Low-repetition-rate femtosecond operation in extended-cavity mode-locked Yb:CALGO laser

International audienceWe report on an extended-cavity mode-locked laser based on an Yb:CALGO crystal operating either at 27 MHz and 93 fs pulse duration or at 15 MHz and 170 fs duration single-pulse regime. To the best of our knowledge this is the first demonstration of an extended-cavity oscillator based on Yb-doped crystal produc- ing sub-100 fs pulses. The pulse energy was 24 nJ directly at the output of the oscillator (and 17 nJ after compression). Based on a similar design, we also demonstrate an unprecedented double-pulse dual- wavelength femtosecond regime. An explanation of this atypical regime is proposed

Mode-locked operation of a diode-pumped femtosecond Yb : SrF2 laser

International audienceFemtosecond mode-locked operation is demonstrated for the first time, to our knowledge, with a Yb:SrF2 crystal. The shortest pulse duration is 143 fs for an average power of 450 mW. The highest average power is 620 mW for a pulse duration of 173 fs. Since Yb:SrF2 corresponds to the longest-lifetime Yb-doped crystal with which the mode-locking operation has been achieved, a detailed analysis is carried out to characterize the quality of the solitonlike regime

High-power diode-pumped cryogenically cooled Yb:CaF2 laser with extremely low quantum defect

International audienceHigh-power diode-pumped laser operation at 992-993nm under a pumping wavelength of 981 of 986nm is demonstrated with Yb:CaF2 operating at cryogenic temperature (77K), leading to extremely low quantum defects of 1.2% and 0.7%, respectively. An average output power of 33Whas been produced with an optical efficiency of 35%. This represents, to the best of our knowledge, the best laser performance ever obtained at such low quantum defects on intense laser lines

On Yb:CaF2 and Yb:SrF2 : Review of spectroscopic and thermal properties and their impact on femtosecond and high power laser performance

International audienceWe present an overview of laser results we obtained with Yb-doped calcium fluoride and its isotype strontium fluoride. In order to study the laser performance in femtosecond and high power regimes, spectral and thermal properties are first discussed including the potential of these crystals at room and cryogenic temperatures. Experimental demonstrations of high-power and ultrashort pulse oscillators and amplifiers are presented and analyzed