A triple Fano resonance Si-graphene metasurface for multi-channel tunable ultra-narrow band sensing.

In this work, a dielectric metasurface composed of a silicon nanodisk etched with a square hole is proposed. By introducing symmetry breaking, the symmetry-protected bound states in the continuum (SP-BIC) is transformed into a quasi-BIC (Q-BIC), simultaneously inducing triple Fano resonances in the near-infrared light band corresponding to one dipole and two Q-BIC resonances. The characteristics of Q-BIC resonances are elucidated through multipole decomposition and near-field distribution analysis.

Regular Periodic Surface Structures on Indium Tin Oxide Film Efficiently Fabricated by Femtosecond Laser Direct Writing with a Cylindrical Lens.

Regular laser-induced periodic surface structures (LIPSS) were efficiently fabricated on indium tin oxide (ITO) films by femtosecond laser direct writing with a cylindrical lens. It was found that randomly distributed nanoparticles and high spatial frequency LIPSSs (HSFL) formed on the surface after a small number of cumulative incident laser pulses per spot, and regular low spatial frequency LIPSSs (LSFL) appeared when more laser pulses accumulated. The mechanism of the transition was studied by real-time absorptance measurement and theoretical simulation.

Electromagnetic origin of femtosecond laser-induced periodic surface structures on GaP crystals.

The formations of different types of laser-induced periodic surface structures (LIPSS) on the surface of GaP crystals with different laser fluence are researched in experiments. The transition from the high spatial frequency LIPSS (HSFL) to the low spatial frequency LIPSS (LSFL) occurred as the number of the irradiated laser pulse increased. The finite difference time domain method combined with the holographic ablation model is used to simulate the LIPSS formation under the irradiation of multiple pulses.

Surface birefringence of regular periodic surface structures produced on glass coated with an indium tin oxide film using a low-fluence femtosecond laser through a cylindrical lens.

Large-area regular laser-induced periodic surface structures (LIPSSs) with a birefringence effect were efficiently produced on a glass surface coated with an indium tin oxide (ITO) film, through irradiation by a femtosecond laser (800 nm, 50 fs, 3 mJ, 1 kHz) focused with a cylindrical lens. The laser fluence of 0.44 J/cm on the coated glass was only one-tenth of that on bare glass, which significantly reduced the thermal effect.

Ultrafast dynamics of the thin surface plasma layer and the periodic ripples formation on GaP crystal irradiated by a single femtosecond laser pulse.

Ultrafast dynamic of thin surface plasma layer plays a crucial role in the formation of periodic surface ripples after laser pulse irradiation. Using the pump-probe imaging technique, a complete scenario of the periodic ripples formation on a GaP surface is demonstrated after being irradiated by single femtosecond laser pulse. The ripples firstly emerge at delay time of several tens of picoseconds, and disappear completely at several hundreds of picoseconds, resulting in a transient overheating solid state ablation crater.

Ultrafast imaging on the formation of periodic ripples on a Si surface with a prefabricated nanogroove induced by a single femtosecond laser pulse.

This paper reports the ultrafast imaging on the formation of periodic surface ripples induced by a single 800 nm, 50 fs laser pulse. The evolution process is observed on a Si surface with a prefabricated nanogroove. The ripples emerge very quickly, only 3 ps after the laser pulse with a fluence of 0.

Direct writing of 150 nm gratings and squares on ZnO crystal in water by using 800 nm femtosecond laser.

We present a controllable fabrication of nanogratings and nanosquares on the surface of ZnO crystal in water based on femtosecond laser-induced periodic surface structures (LIPSS). The formation of nanogrooves depends on both laser fluence and writing speed. A single groove with width less than 40 nm and double grooves with distance of 150 nm have been produced by manipulating 800 nm femtosecond laser fluence.