講演情報
[23p-A310-4]High Harmonic Generation from a Microplasma Source
〇(D)Maria Carla Lupu1, Filchito Renee Bagsican1, Tatsunosuke Hanano1, Michael Man1, Julien Madeo1, Keshav Dani1 (1.OIST)
キーワード：
High harmonic generation
The nonlinear process of High Harmonic Generation (HHG) has enabled table-top ultrafast sources of coherent radiation, mainly in the extreme ultraviolet (XUV) spectral region, with extensive use in a large variety of domains, such as industry, biology, and photoemission science. In particular, the latter would greatly benefit from tunable high repetition rate XUV sources, to map the electronic band structure of materials over a large range of the Brillouin Zone with fast data acquisition. Generally, in HHG experiments, the required peak intensity is reached with the use of femtosecond lasers with a pulse energy in the range of 10 µJ – 1 mJ, typically focused down to a spot diameter of 10 µm – 100 µm, respectively. Focusing the beam tighter than a few microns, thus generating a microplasma, would enable the use of sub-µJ sources. However, a microplasma HHG source is expected to lead to a very poor XUV photon flux. Here, we demonstrate experimentally the high efficiency of a microplasma XUV source, with a photon flux that exceeds 1011 photons/s/harmonic, driven by a pulse energy lower than 1 µJ. As a driving source, we use a noncolinear optical parametric amplifier system operated at 4 MHz repetition rate, from which we tune the driving wavelength between 700 nm - 900 nm. The generation of efficient XUV radiation with sub-µJ class sources could open a new era for spectroscopy and material science.