Silicon as a virtual plasmonic material: Acquisition of its transient optical constants and the ultrafast surface plasmon-polariton excitation

Abstract

Ultrafast intense photoexcitation of a silicon surface is complementarily studied experimentally and theoretically, with its prompt optical dielectric function obtained by means of time resolved optical reflection microscopy and the underlying electron-hole plasma dynamics modeled numerically, using a quantum kinetic approach. The corresponding transient surface plasmon-polariton (SPP) dispersion curves of the photo excited material were simulated as a function of the electron-hole plasma density, using the derived optical dielectric function model, and directly mapped at several laser photon energies, measuring spatial periods of the corresponding SPP mediated surface relief nanogratings. The unusual spectral dynam ics of the surface plasmon resonance, initially increasing with the increase in the electron-hole plasma den sity but damped at high interband absorption losses induced by the high density electron-hole plasma through instantaneous bandgap renormalization, was envisioned through the multi color mapping.

Ultrashort laser pulse ablation of copper, silicon and gelatin: effect of the pulse duration on the ablation thresholds and the incubation coefficients

“…The errors (about 10 %, not shown) arise from the error in determination of the spot size from the slope The errors (about 6 %, not shown) arise from the error in determination of the spot size from the slope The errors (about 7 %, not shown) arise from the error in determination of the spot size from the slope silicon and as s 0.22 for gelatin film. This general trend is consistent with multi-photon absorption as one of the underlying energy deposition mechanisms in these materials, with their power increasing from copper (linear intraband or two-photon interband absorption in near IR) to silicon (two-photon interband absorption in near IR) [24,25] and 3-5 photons near-IR-photon absorption in gelatin. Since multi-photon absorption coefficient increases with increasing intensity, for the fixed laser fluence the threshold fluence decreases with the pulse width.…”

Ultrafast photoionization and excitation of surface-plasmon-polaritons on diamond surfaces

“…Due to its high refractive index in UV-VIS range, it is prospective material for all-dielectric 4 and even hybrid metaldielectric nano-photonic devices and circuits [5][6][7] . Moreover, despite its dielectric character, similarly to silicon it can be promptly turned by intense ultrashort laser pulses into short-lived plasmonic state, becoming socalled "virtual plasmonic material", supporting photoexcitation and propagation of surface plasmon-polaritons (SPPs) [8][9][10] , for potential applications in ultrafast optical switching, spatial phase modulation and saturable absorption 8 , [11][12][13][14] . Meanwhile, experimental ultrafast SPP photoexcitation on diamond surfaces was not realized yet, even though their potential imprinting in surface relief in the form of polarization-dependent laser-induced periodical surface structures (LIPSS, surface ripples) was numerously evidenced [15][16][17] .…”

Specific Features of Formation of Laser‐Induced Periodic Surface Structures on Ge2Sb2Te5 Amorphous Thin Films under Illumination by Femtosecond Laser Pulses

“…A specific feature of an ultrashort pulse interaction with a matter is its ability to change the dielectric properties of the material due to the response of the electronic subsystem, whereas other processes (in particular, associated with the transfer of energy to the lattice) start after the end of the light pulse. Although initially amorphous GST225 is a semiconductor, [ 28 ] when exposed to ultrashort pulses, an increase in the density of free carriers is possible, which at a certain threshold value will lead to “metallization” [ 29–33 ] of the GST surface. In this case, the real part of the dielectric permittivity ε changes its sign to negative and favorable conditions appear for the formation of surface waves.…”