Processing and Functionalization of Vertical Graphene Nanowalls by Laser Irradiation.

The processing of vertical graphene nanowalls (VGNWs) via laser irradiation is proposed as a means to modulate their physicochemical properties. The effects of the number of applied pulses and fluence of each pulse are examined. Raman spectroscopy studies the effect of irradiation on the chemical structure of the VGNWs.

Quantum dot based 3D printed woodpile photonic crystals tuned for the visible.

The development of dynamically responsive 3D photonic elements, which is crucial for the design of active integrated photonic circuits, requires the incorporation of material systems with fast and tunable response. To this end, semiconductor quantum dots have been widely used to perform as the active material system to be integrated; nonetheless, multiple-step processing is usually required for the active functions to be preserved, thereby restricting functionality of integrated 3D quantum photonic elements mostly to the infrared. Here, we report a simple scheme for the realization of visible light active 3D photonic devices by combining direct laser writing with two-photon absorption and synthesis of cadmium sulfide (CdS) nanoparticles.

Ultrafast laser pulse chirp effects on laser-generated nanoacoustic strains in Silicon.

Nanoacoustic strains are generated in Silicon by chirped femtosecond laser pulses using thin Titanium films as transducers. We investigate the effect that the generating laser pulse chirp has on the amplitude of the induced strains, manifested as Brillouin oscillations observed in degenerate femtosecond pump-probe transient reflectivity measurements. The strain amplitude is larger when negatively chirped pulses are used, which is attributed to the more efficient conversion of laser pulse light into acoustic strain in the Titanium transducer.

High acoustic strains in Si through ultrafast laser excitation of Ti thin-film transducers.

The role of thin-film metal transducers in ultrafast laser-generated longitudinal acoustic phonons in Si (100) monocrystal substrates is investigated. For this purpose degenerate femtosecond pump-probe transient reflectivity measurements are performed probing the Brillouin scattering of laser photons from phonons. The influence of the metallic electron-phonon coupling factor, acoustical impedance and film thickness is examined.

Controlling ripples' periodicity using temporally delayed femtosecond laser double pulses.

We demonstrate the capability to control the ripple periodicity on polycrystalline ZnO films by applying temporally delayed femtosecond double pulses. It is shown that there is a characteristic pulse separation time for which one can switch from low- to high- spatial-frequency ripple formation. Results are interpreted based on the relation of the characteristic delay time with the electron-phonon relaxation time of the material.