Fabrication of Periodic Nanostructures on Silicon Suboxide Films with Plasmonic Near-Field Ablation Induced by Low-Fluence Femtosecond Laser Pulses.

Tatsuyoshi Takaya,Lukas Janos Richter,Jürgen Ihlemann,Issei Takahashi,Godai Miyaji

doi:10.3390/nano10081495

Tatsuyoshi Takaya, Lukas Janos Richter + Show 3 more

Open Access

https://doi.org/10.3390/nano10081495

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Abstract

Silicon suboxide (SiOx, x ≈ 1) is a substoichiometric silicon oxide with a large refractive index and optical absorption coefficient that oxidizes to silica (SiO2) by annealing in air at ~1000 °C. We demonstrate that nanostructures with a groove period of 200–330 nm can be formed in air on a silicon suboxide film with 800 nm, 100 fs, and 10 Hz laser pulses at a fluence an order of magnitude lower than that needed for glass materials such as fused silica and borosilicate glass. Experimental results show that high-density electrons can be produced with low-fluence femtosecond laser pulses, and plasmonic near-fields are subsequently excited to create nanostructures on the surface because silicon suboxide has a larger optical absorption coefficient than glass. Calculations using a model target reproduce the observed groove periods well and explain the mechanism of the nanostructure formation.

Highlights

Structures smaller than the wavelength of light can induce optical anisotropy and rotatory and resonant scattering [1,2]
We demonstrate that nanostructures with a groove period of 200–330 nm can be formed in air on a silicon suboxide film with 800 nm, 100 fs, and 10 Hz laser pulses at a fluence an order of magnitude lower than that needed for glass materials such as fused silica and borosilicate glass
Experimental results show that high-density electrons can be produced with low-fluence femtosecond laser pulses, and plasmonic near-fields are subsequently excited to create nanostructures on the surface because silicon suboxide has a larger optical absorption coefficient than glass

Summary

Introduction

Structures smaller than the wavelength of light can induce optical anisotropy and rotatory and resonant scattering [1,2]. Using the birefringence of nanostructures formed in fused silica with fs pulses, Beresna et al developed a spatial-distributed wave plate that can convert a Gaussian beam to structured light such as a radially polarized beam or an optical vortex [12]. This remarkable optical element is currently commercially available. The linearly polarized fs laser pulses were focused in air at nor3mofa1l0 incidence on the silicon suboxide films with a lens with a 250 mm focal length. The focal spot size was 120 μm in diameter at 1/e2 of the maximum intensity

GP CCD

Excited layer Silicon suboxide

Conclusions