Author(s)
Xiyuan Lu, Kartik Srinivasan
Abstract
Photo-induced second harmonic generation (SHG) in centro-symmetric materials like silica and silicon nitride has been commonly explained as an effective second-order (chi(2)) process mediated by a DC electric field and the medium's third-order (chi(3)) nonlinearity. In this explanation, the coherent photogalvanic effect is the source of a DC electric field whose spatial periodicity naturally enables quasi-phase matching. While successful in explaining many observations from experiment, this perspective is incomplete in that it does not provide quantitative predictions of the threshold power for photo-induced SHG, or the origin of amplification in this process. In this letter, we demonstrate how photo-induced SHG can be viewed within the framework of four-wave mixing involving degenerate pump, second harmonic signal, and DC electric field. This DC-Kerr optical parametric oscillation/amplification process explains the threshold behavior of photo-induced SHG, and moreover, predicts unconventional light amplification, both of which we verify by experiments in silicon nitride microresonators.
Citation
Physical Review Applied
Citation
Lu, X.
and Srinivasan, K.
(2021),
Considering photoinduced second-harmonic generation as a DC Kerr optical parametric oscillation or amplification process, Physical Review Applied, [online], https://doi.org/10.1103/PhysRevApplied.16.014027 , https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930754 (Accessed April 25, 2026)
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