Label-free imaging of thick tissue at 1550nm using a femtosecond optical parametric generator

Trägårdh, Johanna and Robb, Gillian and Gadalla, Kamal K.E. and Cobb, Stuart and Travis, Christopher and Oppo, Gian-Luca and McConnell, Gail (2015) Label-free imaging of thick tissue at 1550nm using a femtosecond optical parametric generator. Optics Letters. ISSN 0146-9592

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Abstract

We have developed a simple wavelength tunable optical parametric generator (OPG), emitting broad band 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 .