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21 results on '"Zabelich, Boris"'

1. Monolithic silicon nitride electro-optic modulator enabled by optically-assisted poling

Author

Lafforgue, Christian, Zabelich, Boris, and Brès, Camille-Sophie

Subjects
Physics - Optics
Abstract

Electro-optic (EO) modulation is a key functionality to have on-chip. However, achieving a notable linear EO effect in stoichiometric silicon nitride has been a persistent challenge due to the material's intrinsic properties. Recent advancements revealed that the displacement of thermally excited charge carriers under a high electric field induces a second-order nonlinearity in silicon nitride, thus enabling the linear EO effect in this platform regardless of the material's inversion symmetry. In this work, we show for the first time optically-assisted poling of a silicon nitride microring resonator, removing the need for high-temperature processing of the device. The optical stimulation of charges avoids the technical constraints due to elevated temperature. By optimizing the poling process, we experimentally obtain a long-term effective second-order nonlinearity of 1.2 pm/V. Additionally, we measure the high-speed EO response of the modulator, showing a bandwidth of 4 GHz, only limited by the quality factor of the microring resonator. This work goes towards the implementation of monolithic, compact silicon nitride EO modulators, a necessary component for high-density integrated optical signal processing.

Published
2024

4. Difference-frequency generation in optically poled silicon nitride waveguides

Author

Sahin Ezgi, Zabelich Boris, Yakar Ozan, Nitiss Edgars, Liu Junqiu, Wang Rui N., Kippenberg Tobias J., and Brès Camille-Sophie

Subjects
all-optical poling, difference-frequency generation, integrated optics, second-order nonlinearity, Physics, QC1-999
Abstract

Difference-frequency generation (DFG) is elemental for nonlinear parametric processes such as optical parametric oscillation and is instrumental for generating coherent light at long wavelengths, especially in the middle infrared. Second-order nonlinear frequency conversion processes like DFG require a second-order susceptibility χ (2), which is absent in centrosymmetric materials, e.g. silicon-based platforms. All-optical poling is a versatile method for inducing an effective χ (2) in centrosymmetric materials through periodic self-organization of charges. Such all-optically inscribed grating can compensate for the absence of the inherent second-order nonlinearity in integrated photonics platforms. Relying on this induced effective χ (2) in stoichiometric silicon nitride (Si3N4) waveguides, second-order nonlinear frequency conversion processes, such as second-harmonic generation, were previously demonstrated. However up to now, DFG remained out of reach. Here, we report both near- and non-degenerate DFG in all-optically poled Si3N4 waveguides. Exploiting dispersion engineering, particularly rethinking how dispersion can be leveraged to satisfy multiple processes simultaneously, we unlock nonlinear frequency conversion near 2 μm relying on all-optical poling at telecommunication wavelengths. The experimental results are in excellent agreement with theoretically predicted behaviours, validating our approach and opening the way for the design of new types of integrated sources in silicon photonics.

Published
2021
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13. Fine-tuning of spark-discharge aerosol CVD reactor for single-walled carbon nanotube growth

Author

Iakovlev, Vsevolod Ya, Krasnikov, Dmitry V., Khabushev, Eldar M., Alekseeva, Alena A., Grebenko, Artem K., Tsapenko, Alexey P., Zabelich, Boris Yu, Kolodiazhnaia, Julia V., Nasibulin, Albert G., Skolkovo Institute of Science and Technology, Department of Chemistry and Materials Science, Aalto-yliopisto, and Aalto University

Subjects
Differential mobility analyzer, Aerosol CVD synthesis, Floating catalyst, Catalyst activation, Single-walled carbon nanotubes, Spark-discharge generator
Abstract

We report a development of recently designed apparatus equipped with a spark discharge generator of catalytic nanoparticles for robust aerosol CVD synthesis of single-walled carbon nanotubes. We achieve a profound control over the diameter distribution and the defectiveness of carbon nanotubes produced. By providing a justified comparison of the apparatus with the most abundant aerosol CVD reactor utilizing ferrocene as a catalyst precursor, we reveal the role of the activation procedure: while spark-discharge generator provides aerosol of nanoparticles (ex situ route), the ferrocene vapor decomposes in the nanotube growth zone providing an in situ formation of the catalyst. With other parameters being equal, we reveal the differences in the nanotube growth (diameter and length distribution, yield, defectiveness) employing a comprehensive set of methods (the analysis of differential mobility of the aerosol particles, optical spectroscopy, scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy). We show the ex situ activation in the spark discharge reactor to provide a lower utilization degree of the nanoparticles due to over-coagulation. However, the same method provides an independence of the key performance parameters of the nanotubes opening a room for scaling the apparatus.

Published
2020

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