PORTFOLIO

Optical lasers, as table-top commercial systems, go down in wavelength to the so-called deep ultraviolet at the shortest, such as for instance at wavelength = 193 nm (argon fluoride exciplex) or 157 nm (difluorine excimer). Shorter wavelength lasers in the extreme ultraviolet (EUV: = 10— 100 nm) or even soft X-ray ( < 10 nm) are desirable for enhanced nano-structuring resolution and precision, for nano-scale imaging, and for elemental and structural analysis. In fact, the smallest dimension of a nano-fabrication or nano-inspection process is critically dependent on the wavelength of the illumination, similarly like in ordinary life you feel or manipulate objects with size comparable to your fingers! Henceforth, «smaller fingers» permits to fabricate lighter, wearable, or highly performing nano-devices. High-brightness sources in the XUV spectral range are non-commercial facilities, being km-long billion Euro buildings, attached to particle accelerators. These can be booked only with a few-hour beam-time, after several months for request evaluation (and hopefully no rejection!). Such bottlenecked access to short-wavelength light-sources paces-down the scientific throughput, hinders any optimization, excludes proprietary in-house research under non-disclosure terms as well as any industrial high volume manufacturing. A compact plasma-driven XUV light source, that can be operated in the own lab as «turnkey system», is being integrated in this GRS project, in order to address such gap. Table-top plasma-driven XUV source operation has been indeed demonstrated in proof-of-principle theoretical and experimental studies, by using a micro-plasma as the amplification medium. Micro-plasmas from high-voltage electrical discharges or laser-produced breakdowns are harnessed here as XUV amplification media, similarly like gases or crystal-rods are used as gain media for optical lasers. Thus adopting a plasma gain-medium permits cutting-down the emission wavelength in a table-top footprint.

The availability of a table-top XUV laser for the own user lab (no beam-time limitation!) would benefit the progress and duty cycle in fundamental science, but also open ways for the industry, speeding-up the pace and cutting down the costs. Thus a laser in the XUV wavelength range can be pre-market engineered and prototyped for future market releases.

The short-wavelength laboratory source demonstrator was integrated and operated. This was an ambitious project, for budget and scheduling, but it was accomplished. A hollow cathode discharge produced a plasma in a work gas, such as Ar, He, N2, air, etc. Depending on the working gas, the discharge is repeated at higher or lower replicate rate, in the range of 10-30Hz. This generates short-wavelength light that has been characterized spectroscopically between 5 and 20 nm in wavelength. The operation has been tested for several hours with reliable performance and no loss of intensity. The performance has been tested on several months and several work gas, with results that are being published. The collimation of the light was not so successful as expected which demands more efforts. The source is presently being implemented in application with national (e.g. Paul Scherrer Institute, ETH Zurich) or international (e.g. Ecole Polytechnique Paris) collaborators.

Plasma Soucress Sci. Technlol 26 (2017), «He-doped pseudospark as a home-lab XUV source beyond the beamtime bottleneck», Yunieski Arbelo, Francesco Barbato and Davide Bleiner;
Review of Scientific Instruments 88 (2017), «Induction spectrometry using an ultrafast hollow-coredtoroidal-coil (HTC) detector», Yunieski Arbelo and Davide Bleiner

A delegation of Italian Press in visit to Switzerland came to my laboratory and saw the source in operation