Key words. Imaging depth, femtosecond optical parametric amplifier (OPA), femtosecond regenerative amplifier, femtosecond oscillator, two-photon fluorescence microscopy. SummaryWe experimentally demonstrate, for the first time to the best of our knowledge, two-photon fluorescence imaging with a femtosecond optical parametric amplifier. In particular, we systematically compare the imaging depths of two-photon fluorescence microscopes based on three different excitation sources, including a femtosecond oscillator, a femtosecond regenerative amplifier and the optical parametric amplifier. The results show that the optical parametric amplifier can greatly extend the penetration depth by approximately 227% as compared with that obtained with the femtosecond oscillator due to effective suppression of scattering at longer wavelength and enhanced excitation efficiency enabled by higher pulse energy.

No abstract