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Efficient photoinduced second-harmonic generation in silicon nitride photonics

TitleEfficient photoinduced second-harmonic generation in silicon nitride photonics
Publication TypeJournal Article
Year of Publication2020
AuthorsX. Lu, G. Moille, A. Rao, D. A. Westly, and K. Srinivasan
JournalNature Photonics
Date Published11/2020

Silicon photonics lacks a second-order nonlinear optical (χ(2)) response in general, because the typical constituent materials are centrosymmetric and lack inversion symmetry, which prohibits χ(2) nonlinear processes such as second-harmonic generation (SHG). Here, we realize high SHG efficiency in silicon photonics by combining a photoinduced effective χ(2) nonlinearity with resonant enhancement and perfect phase matching. We show a conversion efficiency of (2,500 ± 100)% W−1 that is two to four orders of magnitude larger than previous field-induced SHG works. In particular, our devices realize milliwatt-level SHG output powers with up to (22 ± 1)% power conversion efficiency. This demonstration is a breakthrough in realizing efficient χ(2) processes in silicon photonics, and paves the way for further integration of self-referenced frequency combs and optical frequency references.