Two-color, two-photon imaging at long excitation wavelengths using a diamond Raman laser

Tragardh, Johanna and Murtagh, Michelle and Robb, Gillian and Parsons, Maddy and Lin, Jipeng and Spence, David J. and McConnell, Gail (2016) Two-color, two-photon imaging at long excitation wavelengths using a diamond Raman laser. Microscopy and Microanalysis. ISSN 1431-9276 (https://doi.org/10.1017/S143192761601151X)

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Abstract

We demonstrate that the second-Stokes output from a diamond Raman laser, pumped by a femtosecond Ti:Sapphire laser, can be used to efficiently excite red-emitting dyes by two-photon excitation at 1080 nm and beyond. We image red fluorescent protein (RFP) expressing HeLa cells, as well as dyes such as Texas Red and Mitotracker Red. We demonstrate the potential for simultaneous two-color, two-photon imaging with this laser by using the residual pump beam for excitation of a green-emitting dye. We demonstrate this for the combination of AlexaFluor 488 and AlexaFluor 568. Because the Raman laser extends the wavelength range of the Ti:Sapphire laser, resulting in a laser system tunable 680 nm-1200 nm it can be used for two-photon excitation of a large variety and combination of dyes.