Fabrication of nano-devices using ultrafast lasers

Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon that can be observed on almost any material after the irradiation by linearly polarized laser beams, particularly when using ultrashort laser pulses with durations in the picosecond to femtosecond range. During the past few years significantly increasing research activities have been reported in the field of LIPSS, since their generation in a single-step process provides a simple way of nanostructuring and surface functionalization towards the control of optical, mechanical or chemical properties.

Relevant publications in this area:

Finding new routes for enhancing the photo-emissive properties of materials without compromising their reliability is a crucial task. In this regard, plasmonic effects are poised to play a key role in the efficiency of photo-emissive devices. In the field of accelerator physics, plasmonic nanostructures enhancing non-linear and multi-photon photoemission from metallic nanoholes and nanogrooves have been demonstrated

There are significant advantages of operating in the linear photoemission regime while exploiting plasmonic effects; the lower intensity allows for higher charge production without material damage, while DUV laser technology currently could allow to operate at high average current. Here, in contrast to non-linear photoemission, the highly localized confinement of surface plasmons can lead to the production of high energy electrons via non-radiative decay, a process characterized by a significant deviation from the Fermi–Dirac distribution traditionally assumed in classic photoemission models. The combination of metallic nanostructures with ultra-thin-film dielectric coatings can further enhance the emission current density and corresponding QE of plasmonic nanostructures

Diamond has long been recognized as an exceptional material featuring outstanding mechanical, thermal and optical properties. Beside these advantageous properties, an important stimulus that boosted researchers' interest in diamond photonics is the discovery of stable, room-temperature single photon emission from color centers hosted in single crystal diamond, as single photon sources are the enabling building block for a variety of quantum technologies in imaging, computing, and communication.

Although integrated photonic devices have been demonstrated in polycrystalline diamond, the performance in polycrystalline diamond will be inferior to single crystal diamond devices. For example, the propagation loss will be higher for polycrystalline diamond waveguides due to scattering at grain boundaries and increased surface roughness, and the grain boundaries in poly-diamond will lead to higher background noise in single photon sources. Here we show an alternative technique based on photo-oxidation processes on diamond surfaces at mesoscopic scales.