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We present a comprehensive study of both continuous-wave and first mode-locked operation of a diode-pumped Yb:Ca3La2(BO3)4 laser in the soliton regime. Using a 976-nm single-spatial-mode, fiber-coupled InGaAs diode laser as pump source, the Yb:Ca3La2(BO3)4 laser delivers a maximum continuous-wave output power of 491 mW at 1050.6 nm, with a slope efficiency of 63%. Passive mode-locking is realized using a commercial semiconductor saturable absorber mirror, generating soliton pulses as short as 35 fs at 1055.9 nm, with an average output power of 96 mW at a pulse repetition rate of ∼66.5 MHz. By optimizing the output coupling, the average output is scaled to 239 mW for slightly longer 48-fs pulses at 1051.9 nm, corresponding to a peak power of 65.9 kW and a laser efficiency of 29%. These results highlight the potential of Yb:Ca3La2(BO3)4 as a gain medium for sub-50-fs ultrafast laser applications.

Dry synthesis is a highly versatile method for the fabrication of nanoporous metal films, since it enables easy and reproducible deposition of single or multi-layers of nanostructured materials that can find intriguing applications in plasmonics, photochemistry and photocatalysis, to name a few. Here, we extend the use of this methodology to the preparation of copper nano-islands that represent an affordable and versatile example of disordered plasmonic substrates. Although the island morphology is disordered, the high density of these nanostructures with large surface area results in a good homogeneity on a macroscale, which is beneficial for plasmonic applications such as bio-sensing and photo-catalysis. With cathodoluminescence and electron-energy-loss spectroscopies we confirm the nano-islands as sources of the local field enhancement and identify the plasmonic resonance bands in the visible and near-infrared spectral range. The decay dynamics of the plasmonic signal are slower in the nano-island as compared to bulk copper films, which can be rationalized by a reduced energy dissipation in the nano-island films. Our study demonstrates a robust and lithography-free fabrication pathway to obtain nanostructured plasmonic copper substrates that represent a highly versatile low-cost alternative for future applications ranging from sensing to photochemistry and photocatalysis.

We present a detailed comparative investigation of the continuous-wave and mode-locked laser performance of a mixed rare-earth calcium oxoborate crystal, Yb:(Gd,Y)Ca4O(BO3)3, abbreviated as Yb:(Gd,Y)COB, for all three principal optical polarizations. Pumped by a low-power, single-transverse-mode, fiber-coupled laser diode at 976 nm, the Yb:(Gd,Y)COB laser generated soliton pulses as short as 32 fs at 1052.4 nm via soft-aperture Kerr-lens mode-locking, delivering an average output power of 51 mW at ∼66.2 MHz for light polarization E || Z. For light polarization E || Y, slightly longer (34 fs) pulses were directly generated at 1053.7 nm, with a higher average output power of 86 mW at ∼66.7 MHz. To the best of our knowledge, these results represent the shortest pulses ever achieved from any Yb3+-doped borate crystal.

Nanoporous metals are a class of nanostructured materials finding extensive applications in multiple fields thanks to their unique properties attributed to their high surface area and interconnected nanoscale ligaments. They can be prepared following different strategies, but the deposition of an arbitrary pure porous metal is still challenging. Recently, a dry synthesis of nanoporous films based on the plasma treatment of metal thin layers deposited by physical vapour deposition has been demonstrated, as a general route to form pure nanoporous films from a large set of metals. An interesting aspect related to this approach is the possibility to apply the same methodology to deposit the porous films as a multilayer. In this way, it is possible to explore the properties of different porous metals in close contact. As demonstrated in this paper, interesting plasmonic properties emerge in a nanoporous Au–Ag bi-layer. The versatility of the method coupled with the possibility to include many different metals, provides an opportunity to tailor their optical resonances and to exploit the chemical and mechanical properties of components, which is of great interest to applications ranging from sensing, to photochemistry and photocatalysis.

We use a vortex retarder approach to generate few optical cycles light pulses carrying orbital angular momentum and arbitrary polarization. The optical vortices' structure is then reconstructed in the spatio-temporal domain.

Nickel (II) oxide, NiO, is a wide band gap Mott insulator characterized by strong Coulomb repulsion between d-electrons and displays antiferromagnetic order at room temperature. NiO has gained attention in recent years as a very promising candidate for applications in a broad set of areas, including chemistry and metallurgy to spintronics and energy harvesting. Here, we report on the fabrication of polycrystalline NiO using spray-pyrolysis technique, which is a deposition technique able to produce quite uniform films of pure and crystalline materials without the need of high vacuum or inert atmospheres. The composition and structure of the NiO thin films were then studied using x-ray diffraction, and atomic force and scanning electron microscopies (SEM). The phononic and magnonic properties of the NiO thin films were also studied via Raman spectroscopy, and the ultrafast electron dynamics by using optical pump probe spectroscopy. We found that the NiO samples display the same phonon and magnon excitations expected for single crystal NiO at room temperature, and that electron dynamics in our system is like those of previously reported NiO mono- and polycrystalline systems synthesized using different techniques. These results prove that spray-pyrolysis can be used as affordable and large-scale fabrication technique to synthesize strongly correlated materials for a large set of applications.

We study ultrafast charge and spin dynamics in magnetoplasmonic Au-Ni nanostructures. Experiments reveal modification of the ultrafast magnetization dynamics time induced by a strong plasmonic response, and the results are supported by numerical modelling.

We use a vortex retarder-based approach to generate few optical cycles light pulses carrying orbital angular momentum (OAM) (known also as twisted light or optical vortex) from a Yb:KGW oscillator pumping a noncollinear optical parametric amplifier generating sub-10 fs linearly polarized light pulses in the near infrared spectral range (central wavelength 850 nm). We characterize such vortices both spatially and temporally by using astigmatic imaging technique and second harmonic generation-based frequency resolved optical gating, respectively. The generation of optical vortices is analyzed, and its structure reconstructed by estimating the spatio-spectral field and Fourier transforming it into the temporal domain. As a proof of concept, we show that we can also generate sub-20 fs light pulses carrying OAM and with arbitrary polarization on the first-order Poincaré sphere.

In the past 20 years, we have reached a broad understanding of many light-driven phenomena in nanoscale systems. The temporal dynamics of the excited states are instead quite challenging to explore, and, at the same time, crucial to study for understanding the origin of fundamental physical and chemical processes. In this review, we examine the current state and prospects of ultrafast phenomena driven by plasmons both from a fundamental and applied point of view. This research area is referred to as ultrafast plasmonics and represents an outstanding playground to tailor and control fast optical and electronic processes at the nanoscale, such as ultrafast optical switching, single photon emission, and strong coupling interactions to tailor photochemical reactions. Here, we provide an overview of the field and describe the methodologies to monitor and control nanoscale phenomena with plasmons at ultrafast timescales in terms of both modeling and experimental characterization. Various directions are showcased, among others recent advances in ultrafast plasmon-driven chemistry and multi-functional plasmonics, in which charge, spin, and lattice degrees of freedom are exploited to provide active control of the optical and electronic properties of nanoscale materials. As the focus shifts to the development of practical devices, such as all-optical transistors, we also emphasize new materials and applications in ultrafast plasmonics and highlight recent development in the relativistic realm. The latter is a promising research field with potential applications in fusion research or particle and light sources providing properties such as attosecond duration.

Photonics and spintronics represent a great promise to overcome the fundamental limits of electronics since light and spins are simultaneously much faster and less dissipative of electrons. In this framework, the quest for energy-efficient data processing and storage functionalities led great attention to the field of femtomagnetism, the study and control of magnetism using ultrashort light pulses. However, our knowledge of magnetic phenomena and ultrafast light-matter interactions in nanoscale magnetic materials is extremely limited. In this work, we introduce a time-resolved magneto-optical pump-probe spectroscopy scheme enabling to access both the thermal and nonthermal spin (and charge) dynamics with sub-15 fs temporal resolution. We test the capabilities of our system on archetypical magnetic and magnetoplasmonic materials, such as Ni thin films and Ni nanodisks.