Two-color multiphoton imaging with a femtosecond diamond Raman laser.

Two-color multiphoton microscopy through wavelength mixing of synchronized lasers has been shown to increase the spectral window of excitable fluorophores without the need for wavelength tuning. However, most currently available dual output laser sources rely on the costly and complicated optical parametric generation approach. In this report, we detail a relatively simple and low cost diamond Raman laser pumped by a ytterbium fiber amplifier emitting at 1055 nm, which generates a first Stokes emission centered at 1240 nm with a pulse width of 100 fs.

Deep in vivo two-photon microscopy with a low cost custom built mode-locked 1060 nm fiber laser.

Here we demonstrate that a mode-locked ytterbium fiber laser for two-photon fluorescence microscopy can be built for $13,000. The laser emits at a wavelength of 1060 nm with a usable average power of 1 W at a repetition rate of 40 MHz and a compressed pulse width of 81 fs at the sample. The laser is used to obtain deep in vivo two-color images of layer-V pyramidal neurons expressing YFP and vasculature labelled with Texas Red at depths up to 900 µm.