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Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides

[Image: see text] Silicon nitride has emerged as a prominent platform for building photonics integrated circuits. While its nonlinear properties based on third-order effects have been successfully exploited, an efficient second harmonic generation in standard stoichiometric silicon nitride (Si(3)N(4...

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Autores principales: Nitiss, Edgars, Liu, Tianyi, Grassani, Davide, Pfeiffer, Martin, Kippenberg, Tobias J., Brès, Camille-Sophie
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2019
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6996647/
https://www.ncbi.nlm.nih.gov/pubmed/32030349
http://dx.doi.org/10.1021/acsphotonics.9b01301
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author Nitiss, Edgars
Liu, Tianyi
Grassani, Davide
Pfeiffer, Martin
Kippenberg, Tobias J.
Brès, Camille-Sophie
author_facet Nitiss, Edgars
Liu, Tianyi
Grassani, Davide
Pfeiffer, Martin
Kippenberg, Tobias J.
Brès, Camille-Sophie
author_sort Nitiss, Edgars
collection PubMed
description [Image: see text] Silicon nitride has emerged as a prominent platform for building photonics integrated circuits. While its nonlinear properties based on third-order effects have been successfully exploited, an efficient second harmonic generation in standard stoichiometric silicon nitride (Si(3)N(4)) waveguides can also be achieved after all-optical poling, as was recently shown. The root of such a phenomenon has been attributed to the inscription of a self-organized periodic space-charge grating along the waveguide, allowing an effective χ((2)) and automatic quasi-phase-matching of pump and second harmonic. However, the different parameters and their role in increasing the efficiency of the process are still not fully comprehended. In this work, we use optical means to identify the general conditions of mode matching occurring during all-optical poling. The overlap integral between pump and second harmonic optical modes is shown to be the governing parameter in determining the features of the χ((2)) gratings. Two-photon microscopy measurements of the χ((2)) gratings reveal the presence of a secondary periodicity in some of the waveguides used in the study. According to overlap integral simulations, such an effect can occur due to mode mixing in the waveguide bends. From a study of poling dynamics, we observe that poling efficiency and rate increase as a function of optical pump power and waveguide length. However, in order to initiate poling, a critical pump intensity, which is lower for longer waveguides, must be coupled into a waveguide. Temporal and thermal stability tests reveal the nature of charge traps responsible for grating inscription. After applying thermally activated hopping as a conductivity mechanism in our samples, we show that only shallow traps seem to be activated during the all-optical poling process.
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spelling pubmed-69966472020-02-04 Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides Nitiss, Edgars Liu, Tianyi Grassani, Davide Pfeiffer, Martin Kippenberg, Tobias J. Brès, Camille-Sophie ACS Photonics [Image: see text] Silicon nitride has emerged as a prominent platform for building photonics integrated circuits. While its nonlinear properties based on third-order effects have been successfully exploited, an efficient second harmonic generation in standard stoichiometric silicon nitride (Si(3)N(4)) waveguides can also be achieved after all-optical poling, as was recently shown. The root of such a phenomenon has been attributed to the inscription of a self-organized periodic space-charge grating along the waveguide, allowing an effective χ((2)) and automatic quasi-phase-matching of pump and second harmonic. However, the different parameters and their role in increasing the efficiency of the process are still not fully comprehended. In this work, we use optical means to identify the general conditions of mode matching occurring during all-optical poling. The overlap integral between pump and second harmonic optical modes is shown to be the governing parameter in determining the features of the χ((2)) gratings. Two-photon microscopy measurements of the χ((2)) gratings reveal the presence of a secondary periodicity in some of the waveguides used in the study. According to overlap integral simulations, such an effect can occur due to mode mixing in the waveguide bends. From a study of poling dynamics, we observe that poling efficiency and rate increase as a function of optical pump power and waveguide length. However, in order to initiate poling, a critical pump intensity, which is lower for longer waveguides, must be coupled into a waveguide. Temporal and thermal stability tests reveal the nature of charge traps responsible for grating inscription. After applying thermally activated hopping as a conductivity mechanism in our samples, we show that only shallow traps seem to be activated during the all-optical poling process. American Chemical Society 2019-12-09 2020-01-15 /pmc/articles/PMC6996647/ /pubmed/32030349 http://dx.doi.org/10.1021/acsphotonics.9b01301 Text en Copyright © 2019 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Nitiss, Edgars
Liu, Tianyi
Grassani, Davide
Pfeiffer, Martin
Kippenberg, Tobias J.
Brès, Camille-Sophie
Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title_full Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title_fullStr Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title_full_unstemmed Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title_short Formation Rules and Dynamics of Photoinduced χ((2)) Gratings in Silicon Nitride Waveguides
title_sort formation rules and dynamics of photoinduced χ((2)) gratings in silicon nitride waveguides
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6996647/
https://www.ncbi.nlm.nih.gov/pubmed/32030349
http://dx.doi.org/10.1021/acsphotonics.9b01301
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