title: Label-free imaging of thick tissue at 1550 nm using a femtosecond optical parametric generator.
abstract: We have developed a simple wavelength-tunable optical parametric generator (OPG), emitting broadband ultrashort pulses with peak wavelengths at 1530-1790 nm, for nonlinear label-free microscopy. The OPG consists of a periodically poled lithium niobate crystal, pumped at 1064 nm by a ultrafast Yb:fiber laser with high pulse energy. We demonstrate that this OPG can be used for label-free imaging, by third-harmonic generation, of nuclei of brain cells and blood vessels in a >150 μm thick brain tissue section, with very little decay of intensity with imaging depth and no visible damage to the tissue at an incident average power of 15 mW.
authors.forename: Johanna
authors.initials: J
authors.lastname: Trägårdh
authors.forename: Gillian
authors.initials: G
authors.lastname: Robb
authors.forename: Kamal K E
authors.initials: KK
authors.lastname: Gadalla
authors.forename: Stuart
authors.initials: S
authors.lastname: Cobb
authors.forename: Christopher
authors.initials: C
authors.lastname: Travis
authors.forename: Gian-Luca
authors.initials: GL
authors.lastname: Oppo
authors.forename: Gail
authors.initials: G
authors.lastname: McConnell
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology; D051379:Mice; D055096:Optical Devices; D061848:Optical Imaging / Q000295:instrumentation / Q000379:methods*