[1] Li R, Wang X X, Zhou Y et al. Advances in nonlinear optical microscopy for biophotonics[J]. Journal of Nanophotonics, 12, 033007(2018).

[2] Zhang Z Y, Wang M X, Liu Z H et al. Application of second harmonic generation in biomedical imaging[J]. Chinese Journal of Lasers, 47, 0207008(2020).

[3] Staedler D, Magouroux T, Hadji R et al. Harmonic nanocrystals for biolabeling: a survey of optical properties and biocompatibility[J]. ACS Nano, 6, 2542-2549(2012).

[4] Rice W, Kaplan D L, Georgakoudi I. Quantitative biomarkers of stem cell differentiation based on intrinsic two-photon excited fluorescence[J]. Journal of Biomedical Optics, 12, 060504(2007).

[5] Duncan M D, Reintjes J, Manuccia T J. Scanning coherent anti-Stokes Raman microscope[J]. Optics Letters, 7, 350-352(1982).

[6] Denk W, Strickler J H, Webb W W. Two-photon laser scanning fluorescence microscopy[J]. Science, 248, 73-76(1990).

[7] Grange R, Lanvin T, Hsieh C L et al. Imaging with second-harmonic radiation probes in living tissue[J]. Biomedical Optics Express, 2, 2532-2539(2011).

[8] Autere A, Jussila H, Dai Y Y et al. Nonlinear optics: nonlinear optics with 2D layered materials[J]. Advanced Materials, 30, 1870172(2018).

[9] Franken P A, Hill A E, Peters C W et al. Generation of optical harmonics[J]. Physical Review Letters, 7, 118-119(1961).

[10] Dempsey W P, Fraser S E, Pantazis P. SHG nanoprobes: advancing harmonic imaging in biology[J]. BioEssays, 34, 351-360(2012).

[11] Čulić-Viskota J, Dempsey W P, Fraser S E et al. Surface functionalization of barium titanate SHG nanoprobes for in vivo imaging in zebrafish[J]. Nature Protocols, 7, 1618-1633(2012).

[12] Fine S, Hansen W P. Optical second harmonic generation in biological systems[J]. Applied Optics, 10, 2350-2353(1971).

[13] Gannaway J N, Sheppard C J R. Second-harmonic imaging in the scanning optical microscope[J]. Optical and Quantum Electronics, 10, 435-439(1978).

[14] Freund I, Deutsch M, Sprecher A. Connective tissue polarity. Optical second-harmonic microscopy, crossed-beam summation, and small-angle scattering in rat-tail tendon[J]. Biophysical Journal, 50, 693-712(1986).

[15] Campagnola P J, Millard A C, Terasaki M et al. Three-dimensional high-resolution second-harmonic generation imaging of endogenous structural proteins in biological tissues[J]. Biophysical Journal, 82, 493-508(2002).

[16] Nucciotti V, Stringari C, Sacconi L et al. Probing myosin structural conformation in vivo by second-harmonic generation microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 107, 7763-7768(2010).

[17] Olivier N, Luengo-Oroz M A, Duloquin L et al. Cell lineage reconstruction of early zebrafish embryos using label-free nonlinear microscopy[J]. Science, 329, 967-971(2010).

[18] Brown R M,, Millard A C, Campagnola P J. Macromolecular structure of cellulose studied by second-harmonic generation imaging microscopy[J]. Optics Letters, 28, 2207-2209(2003).

[19] Freund I, Deutsch M. Second-harmonic microscopy of biological tissue[J]. Optics Letters, 11, 94-96(1986).

[20] Wang N N, Gao Y F, Zheng W et al. Quantitative assessment of age-related changes in aorta based on second harmonic generation microscopy[J]. Chinese Journal of Lasers, 50, 1507102(2023).

[21] Tilbury K, Campagnola P J. Applications of second-harmonic generation imaging microscopy in ovarian and breast cancer[J]. Perspectives in Medicinal Chemistry, 7, 21-32(2015).

[22] Kim E, Steinbrück A, Buscaglia M T et al. Second-harmonic generation of single BaTiO3 nanoparticles down to 22 nm diameter[J]. ACS Nano, 7, 5343-5349(2013).

[23] Bonacina L, Mugnier Y, Courvoisier F et al. Polar Fe(IO3)3 nanocrystals as local probes for nonlinear microscopy[J]. Applied Physics B, 87, 399-403(2007).

[24] Nakayama Y, Pauzauskie P J, Radenovic A et al. Tunable nanowire nonlinear optical probe[J]. Nature, 447, 1098-1101(2007).

[25] Aufray M, Menuel S, Fort Y et al. New synthesis of nanosized niobium oxides and lithium niobate particles and their characterization by XPS analysis[J]. Journal of Nanoscience and Nanotechnology, 9, 4780-4785(2009).

[26] Johnson J C, Yan H Q, Schaller R D et al. Near-field imaging of nonlinear optical mixing in single zinc oxide nanowires[J]. Nano Letters, 2, 279-283(2002).

[27] Duan Y L, Ju C G, Yang G A et al. Aggregation induced enhancement of linear and nonlinear optical emission from a hexaphenylene derivative[J]. Advanced Functional Materials, 26, 8968-8977(2016).

[28] Chervy T, Xu J L, Duan Y L et al. High-efficiency second-harmonic generation from hybrid light-matter states[J]. Nano Letters, 16, 7352-7356(2016).

[29] Xu J L, Semin S, Niedzialek D et al. Self-assembled organic microfibers for nonlinear optics[J]. Advanced Materials, 25, 2084-2089(2013).

[30] Pelayo García de Arquer F, Talapin D V, Klimov V I et al. Semiconductor quantum dots: technological progress and future challenges[J]. Science, 373, eaaz8541(2021).

[31] Ghosh M, Nath S, Sen S et al. Nonlinear optical response and characteristic Raman spectra of phagraphene quantum dots[J]. Physica Scripta, 98, 045109(2023).

[32] Medintz I L, Uyeda H T, Goldman E R et al. Quantum dot bioconjugates for imaging, labelling and sensing[J]. Nature Materials, 4, 435-446(2005).

[33] Petryayeva E, Algar W R, Medintz I L. Quantum dots in bioanalysis: a review of applications across various platforms for fluorescence spectroscopy and imaging[J]. Applied Spectroscopy, 67, 215-252(2013).

[34] Qi X Y, Liu H P, Guo W J et al. New opportunities: second harmonic generation of boron-doped graphene quantum dots for stem cells imaging and ultraprecise tracking in wound healing[J]. Advanced Functional Materials, 29, 1902235(2019).

[35] Nayfeh M H, Akcakir O, Belomoin G et al. Second harmonic generation in microcrystallite films of ultrasmall Si nanoparticles[J]. Applied Physics Letters, 77, 4086-4088(2000).

[36] Nayfeh M H, Rigakis N, Yamani Z. Photoexcitation of Si-Si surface states in nanocrystallites[J]. Physical Review B, 56, 2079-2084(1997).

[37] Hubert C, Billot L, Adam P M et al. Role of surface plasmon in second harmonic generation from gold nanorods[J]. Applied Physics Letters, 90, 4-39(2007).

[38] Gupta A, Swihart M T, Wiggers H. Luminescent colloidal dispersion of silicon quantum dots from microwave plasma synthesis: exploring the photoluminescence behavior across the visible spectrum[J]. Advanced Functional Materials, 19, 696-703(2009).