{'fraction_non_alphanumeric': 0.03292181069958848, 'fraction_numerical': 0.0, 'mean_word_length': 6.371212121212121, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Topology optimization in nonlinear nanophotonics: from frequency conversion to exceptional points

We apply a large-scale inverse design strategy based on topology optimization (TO) toward the automatic discovery of complex nanophotonic structures-new kinds of micropillars, photonic-cyrstal slabs, and waveguides comprising complicated arrangements of subwavelength dielectrics-exhibiting unusual nonlinear and spectral properties. The structures support multiple, tightly confined resonances at far-away wavelengths and exhibit the largest nonlinear confinement factors predicted thus far (oders of magnitude larger than state-of-the-art ring resonators or PhC cavities), leading to highly efficient nonlinear frequency conversion (NFC). The same TO approach can be exploited to design PhCs supporting dual-polarization, dual-wavelength, or highly degenerate Dirac cones, with implications to zero-index metamaterials, topological photonics, and exceptional points (EP).