20-mj-1-ps-ybyag-thin-disk-regenerative-amplifier

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

This is a report on a 100 W, 20 mJ, 1 ps Yb:YAG thin-disk regenerative amplifier. A homemade Yb:YAG thin-disk, Kerr-lens mode-locked oscillator with ...

Ludwig Maximilian University of Munich

Max Planck Institute of Quantum Optics

We demonstrate pulse shortening of 1-ps Yb:YAG thin-disk regenerative amplifier to 500 fs by cross-polarized wave generation (XPW) in a 6 mm BaF<sub>2</sub> crystal. The process is self-compressed and has 8.5% conversion efficiency corresponding to 18 µJ energy. Our theoretical and experimental investigation shows that the factor of 3 spectral broadening and pulse shortening in ps-XPW-generation only happens in unsaturated regime. We demonstrate that the initial spectral chirp affects the spectral broadening and pulse shortening of XPW pulses.

Self-compressed, spectral broadening of a Yb:YAG thin-disk amplifier.

We report on the generation of a multi-octave, phase-stable continuum from the output of a Yb:YAG regenerative amplifier delivering 1-ps pulses with randomly varying carrier-envelope phase (CEP). The intrinsically CEP-stable spectral continuum spans from 450 nm to beyond 2500 nm, covering a spectral range of about 0.6 PHz. The generated coherent broadband light carries an energy of 4 μJ, which can be scaled to higher values if required. The system has been designed and is ideally suited for seeding broadband parametric amplifiers and multichannel synthesizers pumped by picosecond Yb:YAG amplifiers, obviating the need for active timing synchronization required in previous approaches. The presented concept paves the way to cost-effective, reliable all-Yb:YAG single-cycle sources with terawatt peak-power and tens-of-Watts average power.

Near-PHz-bandwidth, phase-stable continua generated from a Yb:YAG thin-disk amplifier.

We reasoned that a prospective assessment of glucocorticoid withdrawal in subjects with asthma would provide insight into the basis for flares of the disease. We therefore enrolled 25 subjects with moderate persistent asthma and treated them for 30 days with inhaled fluticasone propionate (1,760 microg/day) followed by a withdrawal period that lasted until peak expiratory airflow decreased by 25% and FEV(1) by 15% or 6 weeks elapsed. After glucocorticoid withdrawal, 13 of 25 subjects reached the target, whereas 12 subjects did not. The number of eosinophils in bronchial biopsies was increased by glucocorticoid withdrawal in both groups, but increases in airway T cells were found in only those with exacerbation. T-cell accumulation was a reflection of similar increases in both CD4(+) and CD8(+) T cells and was accompanied by increased expression of chemokine CCL5 (regulated upon activation, normal T cell expressed and secreted) in the airway epithelium without activation of the transcription factor nuclear factor-kappaB. The pattern of glucocorticoid-sensitive inflammation during an asthma exacerbation is more reminiscent of an antiviral response than an eosinophil-predominant response to allergen and implies an independent role for airway T cells in mediating asthma flares and in determining glucocorticoid efficacy in the treatment of this disease.

Asthma exacerbations after glucocorticoid withdrawal reflects T cell recruitment to the airway.

We report a 100 W, 20 mJ, 1-ps, all-Yb:YAG thin-disk regenerative amplifier seeded by a microjoule-level Yb:YAG thin-disk Kerr-lens mode-locked oscillator. The regenerative amplifier is implemented in a chirped pulse amplification system and operates at an ambient temperature in air, delivering ultrastable output pulses at a 5 kHz repetition rate and with a root mean square power noise value of less than 0.5%. Second harmonic generation of the amplifier's output in a 1.5 mm-thick BBO crystal results in more than 70 W at 515 nm, making the system an attractive source for pumping optical parametric chirped pulse amplifiers in the visible and near-infrared spectral ranges.

Haochuan Wang

Department of Physics

Ludwig Maximilian University of Munich

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

Haochuan Wang

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Physics

Ludwig Maximilian University of Munich

20 mJ, 1 ps Yb:YAG Thin-disk Regenerative Amplifier

Department of Physics