Control of multiphoton and avalanche ionization using an ultraviolet-infrared pulse train in femtosecond laser micro/nano-machining of fused silica

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DOIResolve DOI: http://doi.org/10.1117/12.2035290
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TypeArticle
Proceedings titleLaser-based Micro- and Nanoprocessing VIII
Series titleProceedings of SPIE - The International Society for Optical Engineering; Volume 8968
ConferenceLaser-Based Micro- and Nanoprocessing VIII, February 4-6, 2014, San Francisco, CA, USA
ISSN0277-786X
ISBN9780819498816
Article number89680G
SubjectFabrication; Multiphoton processes; Nanostructures; Ultrafast lasers; Ultrashort pulses; Avalanche ionization; Avalanche process; Damage threshold; Micro and nanostructures; Multi-photon absorption; On-electron density; Shorter wavelength; Ultraviolet , uv; Pulse generators
AbstractWe report on the experimental results of micro- and nanostructures fabricated on the surface of fused silica by a train of two femtosecond laser pulses, a tightly focused 266 nm (ultraviolet, UV) pulse followed by a loosely focused 800 nm (infrared, IR) pulse. By controlling the fluence of each pulse below the damage threshold, micro- and nanostructures are fabricated using the combined beams. The resulting damage size is defined by the UV pulse, and a reduction of UV damage threshold is observed when the two pulses are within ∼ 1 ps delay. The effects of IR pulse duration on the UV damage threshold and shapes are investigated. These results suggest that the UV pulse generates seed electrons through multiphoton absorption and the IR pulse utilizes these electrons to cause damage by avalanche process. A single rate equation model based on electron density can be used to explain these results. It is further demonstrated that structures with dimensions of 124 nm can be fabricated on the surface of fused silica using 0.5 NA objective. This provides a possible route to XUV (or even shorter wavelength) laser nano-machining with reduced damage threshold.
Publication date
PublisherSPIE
LanguageEnglish
AffiliationNational Research Council Canada; Security and Disruptive Technologies
Peer reviewedYes
NPARC number21272864
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Record identifier3f8e32cb-7394-4f5b-8c67-d3bf81ffd52a
Record created2014-12-03
Record modified2016-05-09
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