Cavity-enhanced second-harmonic generation via nonlinear-overlap optimization
Author(s)
Lin, Zin; Lončar, Marko; Rodriguez, Alejandro W.; Liang, Xiangdong; Johnson, Steven G
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We describe a novel approach based on topology optimization that enables automatic discovery of wavelength-scale photonic structures for achieving high-efficiency second-harmonic generation (SHG). A key distinction from previous formulation and designs that seek to maximize Purcell factors at individual frequencies is that our method aims to not only achieve frequency matching (across an entire octave) and large radiative lifetimes, but also optimizes the equally important nonlinear-coupling figure of merit [bar over β], involving a complicated spatial overlap-integral between modes. We apply this method to the particular problem of optimizing micropost and grating-slab cavities (one-dimensional multilayered structures) and demonstrate that a variety of material platforms can support modes with the requisite frequencies, large lifetimes 𝑄 > 10[superscript 4], small modal volumes ∼(𝜆/𝑛)[superscript 3], and extremely large [bar over β] ≳ 10−2, leading to orders of magnitude enhancements in SHG efficiency compared to state-of-the-art photonic designs. Such giant [bar over β] alleviate the need for ultranarrow linewidths and thus pave the way for wavelength-scale SHG devices with faster operating timescales and higher tolerance to fabrication imperfections.
Date issued
2015-05Department
Massachusetts Institute of Technology. Department of MathematicsJournal
Optica
Publisher
Optical Society of America
Citation
Lin, Zin et al. “Cavity-Enhanced Second-Harmonic Generation via Nonlinear-Overlap Optimization.” Optica 3.3 (2016): 233.
Version: Original manuscript
ISSN
2334-2536