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Title: Femtosecond laser surface structuring of silicon using optical vortex beams generated by a q-plate

We report on laser surface structuring of silicon using Ti:Sa femtosecond laser ablation with optical vortex beams. A q-plate is used to generate an optical vortex beam with femtosecond pulse duration through spin-to-orbital conversion of the angular momentum of light. The variation of the produced surface structures is investigated as a function of the number of pulses, N, at laser fluence slightly above the ablation threshold value. At low N (≈10), only surface corrugation of the irradiated, ring-shaped area is observed. This is followed by a progressive formation of regular ripples at larger N (≈100–500), which eventually transform in smaller columnar structures for N ≈ 1000. Moreover, the central, non-ablated part is gradually decorated by nanoparticles produced during laser ablation, a process which eventually leads to the formation of a central turret of assembled nanoparticles. Our experimental findings suggest the importance of a feedback mechanism and a cumulative effect on the formation of ripples with interesting patterns not achievable by the more standard beams with a Gaussian intensity profile.
Authors:
; ; ; ;  [1] ;  [2] ; ;  [3] ; ;  [4]
  1. Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)
  2. (Italy)
  3. CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy)
  4. CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)
Publication Date:
OSTI Identifier:
22299881
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABLATION; FEEDBACK; IRRADIATION; LASER RADIATION; LIMITING FRAGMENTATION; PULSES; SILICON; SPIN; SURFACES; VISIBLE RADIATION; VORTICES NANOPARTICLES