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Title: Engineered second-order nonlinearity in silicon nitride

The lack of a bulk second-order nonlinearity (χ(2)) in silicon nitride (Si3N4) keeps this low-loss, CMOS-compatible platform from key active functions such as Pockels electro-optic (EO) modulation and efficient second harmonic generation (SHG). We demonstrate a successful induction ofχ(2)in Si3N4through electrical poling with an externally-applied field to align the Si-N bonds. This alignment breaks the centrosymmetry of Si3N4, and enables the bulkχ(2). The sample is heated to over 500°C to facilitate the poling. The comparison between the EO responses of poled and non-poled Si3N4, measured using a Si3N4micro-ring modulator, shows at least a 25X enhancement in ther33EO component. The maximumχ(2)we obtain through poling is 0.30pm/V. We observe a remarkable improvement in the speed of the measured EO responses from 3 GHz to 15 GHz (3 dB bandwidth) after the poling, which confirms theχ(2)nature of the EO response induced by poling. This work paves the way for high-speed active functions on the Si3N4platform.

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Publication Date:
Journal Name:
Optical Materials Express
Page Range or eLocation-ID:
Article No. 237
Optical Society of America
Sponsoring Org:
National Science Foundation
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