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Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses

Three-dimensional laser writing inside silicon remains today inaccessible with the shortest infrared light pulses unless complex schemes are used to circumvent screening propagation nonlinearities. Here, we explore a new approach irradiating silicon with trains of femtosecond laser pulses at repetit...

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Detalles Bibliográficos
Autores principales: Wang, Andong, Das, Amlan, Grojo, David
Formato: Online Artículo Texto
Lenguaje:English
Publicado: AAAS 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245002/
https://www.ncbi.nlm.nih.gov/pubmed/32510057
http://dx.doi.org/10.34133/2020/8149764
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author Wang, Andong
Das, Amlan
Grojo, David
author_facet Wang, Andong
Das, Amlan
Grojo, David
author_sort Wang, Andong
collection PubMed
description Three-dimensional laser writing inside silicon remains today inaccessible with the shortest infrared light pulses unless complex schemes are used to circumvent screening propagation nonlinearities. Here, we explore a new approach irradiating silicon with trains of femtosecond laser pulses at repetition rates up to 5.6 THz that is order of magnitude higher than any source used for laser processing so far. This extremely high repetition rate is faster than laser energy dissipation from microvolume inside silicon, thus enabling unique capabilities for pulse-to-pulse accumulation of free carriers generated by nonlinear ionization, as well as progressive thermal bandgap closure before any diffusion process comes into play. By space-resolved measurements of energy delivery inside silicon, we evidence changes in the interplay between detrimental nonlinearities and accumulation-based effects. This leads to a net increase on the level of space-time energy localization. The improvement is also supported by experiments demonstrating high performance for 3D laser writing inside silicon. In comparison to repeated single pulses, irradiation with trains of only four-picosecond pulses with the same total energy leads to an apparent decrease of the energy threshold for modification and drastic improvements on the repeatability, uniformity, and symmetricity of the produced features. The unique benefits of THz bursts can provide a new route to meet the challenge of 3D inscription inside narrow bandgap materials.
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spelling pubmed-72450022020-06-05 Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses Wang, Andong Das, Amlan Grojo, David Research (Wash D C) Research Article Three-dimensional laser writing inside silicon remains today inaccessible with the shortest infrared light pulses unless complex schemes are used to circumvent screening propagation nonlinearities. Here, we explore a new approach irradiating silicon with trains of femtosecond laser pulses at repetition rates up to 5.6 THz that is order of magnitude higher than any source used for laser processing so far. This extremely high repetition rate is faster than laser energy dissipation from microvolume inside silicon, thus enabling unique capabilities for pulse-to-pulse accumulation of free carriers generated by nonlinear ionization, as well as progressive thermal bandgap closure before any diffusion process comes into play. By space-resolved measurements of energy delivery inside silicon, we evidence changes in the interplay between detrimental nonlinearities and accumulation-based effects. This leads to a net increase on the level of space-time energy localization. The improvement is also supported by experiments demonstrating high performance for 3D laser writing inside silicon. In comparison to repeated single pulses, irradiation with trains of only four-picosecond pulses with the same total energy leads to an apparent decrease of the energy threshold for modification and drastic improvements on the repeatability, uniformity, and symmetricity of the produced features. The unique benefits of THz bursts can provide a new route to meet the challenge of 3D inscription inside narrow bandgap materials. AAAS 2020-05-14 /pmc/articles/PMC7245002/ /pubmed/32510057 http://dx.doi.org/10.34133/2020/8149764 Text en Copyright © 2020 Andong Wang et al. http://creativecommons.org/licenses/by/4.0/ Exclusive Licensee Science and Technology Review Publishing House. Distributed under a Creative Commons Attribution License (CC BY 4.0).
spellingShingle Research Article
Wang, Andong
Das, Amlan
Grojo, David
Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title_full Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title_fullStr Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title_full_unstemmed Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title_short Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses
title_sort ultrafast laser writing deep inside silicon with thz-repetition-rate trains of pulses
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245002/
https://www.ncbi.nlm.nih.gov/pubmed/32510057
http://dx.doi.org/10.34133/2020/8149764
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