  Multiphoton microscopes employ femtosecond lasers as light sources because
the high peak power of the ultrashort pulse allows for multiphoton excitation
of fluorescence in the examined sample. However, such short pulses are
susceptible to broadening in a microscope's highly dispersive optical elements
and require careful dispersion management, otherwise decreasing excitation
efficiency. Here, we have developed a 10 nJ Yb:fiber picosecond laser with an
integrated pulse picker unit and evaluated its performance in multiphoton
microscopy. Our results show that performance comparable to femtosecond pulses
can be obtained with picosecond pulses only by reducing the pulse repetition
rate and that such pulses are significantly less prone to the effect of
chromatic dispersion. These findings proved that the temporal compression of
fiber lasers is not always efficient, and it can be omitted by using a smaller
and easier-to-use all-fiber setup.
