• Ahn SJ, Ruiz-Uribe NE, Li B, Porter J, Sakadzic S, Schaffer CB (2020) Label-free assessment of hemodynamics in individual cortical brain vessels using third harmonic generation microscopy. Biomedical Optics Express 11(5), 2665-2678. https://doi.org/10.1364/BOE.385848

  • Akturk S, Gu X, Kimmel M, Trebino R (2006) Extremely simple single-prism ultrashort- pulse compressor. Opt Express 14(21), 10101-10108. https://doi.org/10.1364/OE.14.010101

  • Bertie JE, Lan Z (1996) Infrared Intensities of Liquids XX: The intensity of the OH stretching band of liquid water revisited, and the best current values of the optical constants of H2O(l) at 25°C between 15,000 and 1 cm-1. Applied Spectroscopy 50, 1047-1057. https://www.osapublishing.org/as/abstract.cfm?uri=as-50-8-1047

  • Cable JR, Albrecht AC (1986) A condensed phase study of the benzene B2u ← A1g three-photon transition. J Chem Phys 85(6), 3155–3164. https://doi.org/10.1063/1.450982

  • Catelano IM, Cingolani A (1979) Three-photon absorption coefficient determination by means of nonlinear luminescence experiments. J Appl Phys 50(9), 5638-5641. https://doi.org/10.1063/1.326738

  • Chen B, Huang X, Gou D, Zeng J, Chen G, Pang M, Hu Y, Zhao Z, Zhang Y, Zhou Z, Wu H, Cheng H, Zhang Z, Xu C, Li Y, Chen L, Wang A (2018) Rapid volumetric imaging with Bessel-beam three-photon microscopy. Biomed. Opt. Express 9(4), 1992-2000. https://doi.org/10.1364/BOE.9.001992

  • Cheng L, Horton NG, Wang K, Chen S, Xu C (2014) Measurements of multiphoton action cross sections for multiphoton microscopy. Biomedical Optics Express 5(10), 3427–3533. https://doi.org/10.1364/BOE.5.003427.

  • Chow D, Sinefeld D, Kolkman KE, Ouzounov DG, Akbari N, Tatarsky R, Bass A, Xu C, Fetcho JR (2020) Deep three-photon imaging of the brain in intact adult zebrafish. Nature Methods 17, 605–608. https://doi.org/10.1038/s41592-020-0819-7

  • Curcio JA, Petty CC (1951) The near infrared absorption spectrum of liquid water. J Opt Soc Am 41(5), 302-304. https://doi.org/10.1364/JOSA.41.000302

  • Davey AP, Bourdin E, Henari F, Blau W (1995) Three photon induced fluorescence from a conjugated organic polymer for infrared frequency upconversion. Appl Phys Lett 67(7), 884–885. https://doi.org/10.1063/1.114724

  • Debarre D, Suppato W, Beaurepaire E (2005) Structure sensitivity in third-harmonic generation microscopy. Optics Letters 30(16), 2134-2136. https://doi.org/10.1364/OL.30.002134

  • Deng X, Zhuang Z, Liu H, Qiu P, Wang KE (2019) Measurement of 3-photon excitation and emission spectra and verification of Kasha’s rule for selected fluorescent proteins excited at the 1700-nm window. Optics Express 27(9) 12723-12731. https://doi.org/10.1364/OE.27.012723

  • Farinella DM, Roy A, Liu CJ, Kara P (2020) Improving laser standards for three-photon microscopy. bioRchiv https://doi.org/10.1101/2020.09.09.289603

  • Farrar MJ, Wise FW, Fetcho JR, Schaffer CB (2011) In vivo imaging of myelin in the vertebrate central nervous system using third harmonic generation microscopy. Biophysical Journal 100(5), 1362-1371. https://doi.org/10.1016/j.bpj.2011.01.031

  • Gryczynski I, Malak H, Lakowicz JR (1995a) Three-photon induced fluorescence of 2,5-diphenyloxazole with a femtosecond Ti:sapphire laser. Chemical Physics Letters 245, 30-35. https://doi.org/10.1016/0009-2614(95)00958-7

  • Gryczynski I, Szmaczinski H, Lakowicz JR (1995b) On the possibility of calcium imaging using Indo-1 with three-photon excitation. Photochemistry & Photobiology 62(4), 804–808. https://doi.org/10.1111/j.1751-1097.1995.tb08733.x

  • Gryczynski I, Malak H, Hell SW, Lakowicz JR (1996a) Three-photon excitation of 2,5-bis(4- biphenyl)oxazole. J Biomed Opt 1(4), 473-480. https://doi.org/10.1111/j.1751-1097.1995.tb08733.x

  • Gryczynski I, Malak H, Lakowicz JR (1996b) Three-photon excitation of tryptophan derivative using a fs Ti:sapphire laser. Biospectroscopy 2, 9-15. https://doi.org/10.1002/(SICI)1520-6343(1996)2:1<9::AID-BSPY2>3.0.CO;2-6

  • Grubb SG, Otis CE, Haber KS, Albrecht AC (1984) The three photon spectrum of the 1B2u ← 1A1g transition in benzene: analysis of vibronic and rotational structure. J Chem Phys 81(12), 5255–5265. https://doi.org/10.1063/1.447692

  • Guesmi K, Abdeladim L, Tozer S, Mahou P, Kumamoto T, Jurkus K, Rigaud P, Loulier K, Dray K, Georges P, Hanna M, Livet J, Supatto W, Beaurepaire E, Druon F (2018) Dual-color deep-tissue three-photon microscopy with a multiband infrared laser. Light: Sci. Appl. 7(1), 12. https://doi.org/10.1038/s41377-018-0012-2

  • Hale GM, Querry MR (1073) Optical constants of water in the 200-nm to 200µm wavelength region. Applied Optics 12(3), 555-563. https://doi.org/10.1364/AO.12.000555

  • He GS, Bhalkawar JD, Prasad PN, Rhinhard BN (1995) Three-photon absorption-induced fluorescence and optical limiting effects in an organic compound. Opt Lett 20(14), 1524–1526. https://doi.org/10.1364/OL.20.001524

  • Hell SW, Bahlmann K, Schrader M, Soini A, Malak H, Gryczynski I, Lakowicz JR (1996) Three-photon excitation in fluorescence microscopy. J Biomed Opt 1(1), 71-74. https://doi.org/10.1117/12.229062

  • Horton NG, Wang K, Kobat D, Clark CG, Wise FW, Schaffer CB, Xu C (2013) In vivo three-photon microscopy of subcortical structures within an intact mouse brain. Nature Photonics 7, 205-209. https://doi.org/10.1038/nphoton.2012.336

  • Horton NG, Xu C (2015) Dispersion compensation in three-photon fluorescence microscopy at 1,700 nm. Biomedical Optics Express 6(4), 1392–1397. https://doi.org/10.1364/BOE.6.001392

  • Huland DM, Charan K, Ouzounov DG, Jones JS, Nishimura N, Xu C (2013) Three-photon excited fluorescence imaging of unstained tissue using a GRIN lens endoscope. Biomedical Optics Express 4, 652–658. https://doi.org/10.1364/BOE.4.000652

  • Hsu K-J, Lin Y-Y, Chiang A-S, Chu S-W (2018) Whole-brain imaging and characterization of Drosophila brains based on one-, two-, and three-photon excitations. bioRchiv http://dx.doi.org/10.1101/339531

  • Jabłoński A (1933) Efficiency of anti-Stokes fluorescence in dyes. Nature 131, 839-840. https://doi.org/10.1038/131839b0

  • Jacques SL (2013) Optical properties of biological tissues: a review. Phys Med Biol 58, R37–R61. https://doi.org/10.1088/0031-9155/58/11/R37

  • Ji N, Milkie DE, Betzig E (2010) Adaptive optics via pupil segmentation for high-resolution imaging in biological tissues. Nature Methods 7(2), 141-147. https://doi.org/10.1038/nmeth.1411
  • Ji N, Sato TR, Betzig E (2012) Characterization and adaptive optical correction of aberrations during in vivo imaging in the mouse cortex. PNAS 190(1), 22-27. https://doi.org/10.1073/pnas.1109202108

  • Kleinfeld D, Denk W (2000) Two-photon imaging of neocortical microcirculation, in Imaging Neurons: A Laboratory Manual, Yuste, Lanni, Konnerth, eds. Cold Spring Harbor Laboratory Press, Cold Spring Harbor.

  • Klioutchnikov A, Wallace DJ, Frosz MH, Zeltner R, Sawinski J, Pawlak V, Voit K-M, Russell P St.J, Kerr JND (2020) Three-photon head-mounted microscope for imaging deep cortical layers in freely moving rats. Nature Methods 17, 509–513. https://doi.org/10.1038/s41592-020-0817-9

  • Kobat D, Durst ME, Nishimura N, Wong AW, Schaffer CB, Xu C (2009) Deep tissue multiphoton microscopy using longer wavelength excitation. Optics Express 17(16), 13354-13364. https://doi.org/10.1364/OE.17.013354

  • Kobat D, Horton NG, Xu C (2011) In vivo two-photon microscopy to 1.6-mm depth in mouse cortex. J Biomed Opt 16(10), 106014. https://doi.org/10.1117/1.3646209
  • Li B, Wu C, Wang M, Charan K, Xu C (2019) An adaptive excitation source for high-speed multiphoton microscopy. Nature Methods, in press. https://doi.org/10.1038/s41592-019-0663-9
  • Liu H, Chen X, Deng X, Zhuang Z, Tong S, Xie W, Li J, Qiu P, Wang K (2020a) In vivo deep-brain blood flow speed measurement through third-harmonic generation imaging excited at the 1700-nm window. Biomedical Optics Express 11(5), 2738-2744. https://doi.org/10.1364/BOE.389662
  • Liu CJ, Roy A, Simons AA, Farinella DM, Kara P (2020b) Three‑photon imaging of synthetic dyes in deep layers of the neocortex. Scientific Reports 10, 16351. https://doi.org/10.1038/s41598-020-73438-w
  • Liu H, Deng X, Tong S, He C, Cheng H, Zhuang Z, Gan M, Li J, Xie W, Qiu P, Wang K (2019) In Vivo deep-brain structural and hemodynamic multiphoton microscopy enabled by quantum dots. Nano Letters 19, 5260-5265. https://doi.org/10.1021/acs.nanolett.9b01708
  • Maiti S, Shear JB, Williams RM, Zipfel WR, Webb WW (1997) Measuring serotonin distribution in live cells with three-photon excitation. Science 275, 530-532. https://doi.org/10.1126/science.275.5299.530

  • Mueller M, Squier J, Wilson KR, Brakenhoff GJ (1998) 3D microscopy of transparent objects using third-harmonic generation. Journal of Microscopy 191(3), 266-274. https://doi.org/10.1046/j.1365-2818.1998.00399.x

  • Norris G, Amor R, Dempster J, Amos WM, McConnell G (2012) A promising new wavelength region for three-photon fluorescence microscopy of live cells. J Microscopy 246(3), 266-273. https://doi.org/10.1111/j.1365-2818.2012.03610.x

  • Ouzounov DG, Wang T, Wang M, Feng DD, Horton NG, Cruz-Hernández JC, Cheng YT, Reimer J, Tolias AS, Nishimura N, Xu C (2017) In vivo three-photon imaging of activity of GCaMP6-labeled neurons deep in intact mouse brain. Nature Methods 14, 388-329. https://doi.org/10.1038/nmeth.4183

  • Ouzounov DG, Wang T, Wu C, Xu C (2019) GCaMP6 ΔF/F dependence on the excitation wavelength in 3-photon and 2-photon microscopy of mouse brain activity. Biomedical Optics Express 10(7), 3343-3352. https://doi.org/10.1364/BOE.10.003343

  • Podgorski K, Ranganathan G (2016) Brain heating induced by near-infrared lasers during multiphoton microscopy. J Neurophysiol. 116, 1012–1023. https://doi.org/10.1152/jn.00275.2016

  • Prevedel R, Verhoef AJ, Pernía-Andrade AJ, Weisenburger S, Huang BS, Nöbauer T, Fernández A, Delcour JE, Golshani P, Baltuska A, Vaziri A (2016) Fast volumetric calcium imaging across multiple cortical layers using sculpted light. Nature Methods 13(12), 1021-1028. https://doi.org/10.1038/nmeth.4040
  • Rehberg M, Krombach F, Pohl U, Dietzel S (2011) Label-free 3D visualization of cellular and tissue structures in intact muscle with second and third hermonic generation microscopy. PLoS ONE 6(11), e28237. https://doi.org/10.1371/journal.pone.0028237

  • Richards & Wolf (1959) Electromagnetic diffraction in optical systems, II. Structure of the image field in an aplanatic system. Proc Royal Soc A 253(1274), 358-379. https://doi.org/10.1098/rspa.1959.0200

  • Rodriguez C, Liang Y, Lu R, Ji N (2018) Three-photon fluorescence microscopy with an axial elongated Bessel focus. Optics Letters 43(8), 1914-1917. https://doi.org/10.1364/OL.43.001914

  • Rowlands CJ, Park D, Bruns OT, Piatkevich KD, Fukumura D, Jain RK, Bawendi MG, Boyden ES, So PTC (2017) Wide-field three-photon excitation of biological samples. Light: Science and Applications 6, e16255. doi.org/10.1038/lsa.2016.255

  • Shreve AP, Albrecht AC (1991) Three-photon fluorescence excitation study of the S0(A1g) → S1(B2u) transition in neat liquid benzene. J Chem Phys 94(8), 5772–5773. https://doi.org/10.1063/1.460461

  • Sinefeld D, Paudel HP, Ouzounov DG, Bifano TG, Xu C (2015) Adaptive optics in multiphoton microscopy: comparison of two, three and four photon fluorescence. Opt. Express 23(24), 31472–31483. https://doi.org/10.1364/OE.23.031472

  • SinghS, Bradley LT (1964) Three-photon absorption in nathalene crystals by laser excitation. Physical Review Letters 12(22), 612-614. https://doi.org/10.1103/PhysRevLett.12.612

  • Small D, Jones JS, Tendler II, Miller PE, Ghetti A, Nishimura N (2018) Label-free imaging of atherosclerotic plaques using third-harmonic generation microscopy. Biomedical Optics Express 9(1), 214-229. https://doi.org/10.1364/BOE.9.000214.

  • Takasaki K, Tsyboulski D, Waters J (2019) Dual-plane 2-photon microscopy with remote focusing. Biomedical Optics Express 10(11), 5585-5599. https://doi.org/10.1364/BOE.10.005585

  • Takasaki K, Abbasi-Asl R, Waters J (2020) Superficial bound of the depth limit of 2-photon imaging in mouse brain. eNeuro 7(1), 1-10. https://doi.org/10.1523/ENEURO.0255-19.2019

  • Tao X, Lin H-H, Lam T, Rodriguez R, Wang JW, Kubby J (2015) Transcutical imaging with cellular and subcellular resolution. Biomedical Optics Express 8(3), 1277-1289. https://doi.org/10.1364/BOE.8.001277
  • Theer P, Denk W (2006) On the fundamental imaging-depth limit in two-photon microscopy. J Opt Soc Am A 23(12), 3139-3149. https://doi.org/10.1364/JOSAA.23.003139
  • Theer P, Hasan MT, Denk W (2003) Two-photon imaging to a depth of 1000 µm in living brains by use of a Ti:Al2O3 regenerative amplifier. Optics Letters 28(12), 1022-1024. https://doi.org/10.1364/OL.28.001022

  • Wang M, Kim M, Xia F, Xu C (2019) Impact of the emission wavelengths on in vivo multiphoton imaging of mouse brains. Biomedical Optics Express 10(4), 1905-1918. https://doi.org/10.1364/BOE.10.001905

  • Wang M, Wu C, Sinefeld D, Li B, Xia F, Xu C (2018a) Comparing the effective attenuation lengths for long wavelength in vivo imaging of the mouse brain. Biomedical Optics Express 9(8), 3534-3543. https://doi.org/10.1364/BOE.9.003534

  • Wang T, Ouzounov DG, Wang M, Xu C (2017) Quantitative comparison of two-photon and three-photon activity imaging of GCaMP6s-labeled neurons in vivo in the mouse brain. Optics in the Life Sciences. https://doi.org/10.1364/BRAIN.2017.BrM4B.4

  • Wang T, Ouzounov DG, Wu C, Horton NG, Zhang B, Wu C, Zhang Y, Schnitzer MJ, Xu C (2018b) Three-photon imaging of mouse brain structure and function through the intact skull. Nature Methods 15(10), 789–792. https://doi.org/10.1038/s41592-018-0115-y

  • Wang T, Wu C, Ouzounov DG, Gu W, Xia F, Kim M, Yang X, Warden MR, Xu C (2020a) Quantitative analysis of 1300-nm three-photon calcium imaging in the mouse brain. eLife 9:e53205. https://doi.org/10.7554/eLife.53205

  • Wang T, Xu C (2020b) Three-photon neuronal imaging in deep mouse brain. Optica https://doi.org/10.1364/OPTICA.395825

  • Weisenburger S, Tejera F, Demas J, Chen B, Manley J, Sparks FT, Traub FM, Daigle T, Zeng H, Losonczy A, Vaziri A (2019) Volumetric Ca2+ imaging in the mouse brain using hybrid multiplexed sculpted light microscopy. Cell 177(4), 1050–1066.e14. https://doi.org/10.1016/j.cell.2019.03.011

  • Witte S, Negrean A, Lodder JC, de Kock CPJ, Testa Silva G, Mansvelder HD, Groot ML (2011) Label-free live brain imaging and targeted patching with third-harmonic generation microscopy. PNAS 108(15), 5970-5975. https://doi.org/10.1073/pnas.1018743108
  • Wokosin DL, Centonze VE, Crittenden S, White J (1996) Bioimaging 4, 208-214. https://doi.org/10.1002/1361-6374(199609)4:3<208::AID-BIO11>3.0.CO;2-J

  • Xu C, Webb WW (1996) Measurement of two-photon excitation cross sections of molecular fluorophores with data from 690 to 1050 nm. J Opt Soc Am B 13, 481-491. https://doi.org/10.1364/JOSAB.13.000481

  • Yildirim M, Sugihara H, So PTC, Sur M (2019) Functional imaging of visual cortical layers and subplate in awake mice with optimized three photon microscopy. Nature Communications 10:177, 1-12. https://doi.org/10.1038/s41467-018-08179-6

  • Ying J, Liu F, Alfano RR (1999) Spatial distribution of two-photon-excited fluorescence in scattering media: erratum. Applied Optics 38(10), 2151. https://doi.org/10.1364/AO.38.000224