Custom Ultrafast Lasers
Multiphoton microscopy relies upon ultrafast pulsed lasers to provide the peak power necessary to achieve two- or three-photon excitation. While Ti:sapphire lasers have been the workhorse of the multiphoton microscopy field for the past 25 years, they are not optimal for deep imaging and require the use of expensive oscillators or amplifiers to achieve greater penetration depths. Recent advances in fiber optic technology have allowed for the creation of a new class of fiber-based lasers that offer longer excitation wavelengths and therefore deeper penetration into cortial tissue.
Our lab has built a custom mode-locked ytterbium fiber laser (1060 nm) that can achieve imaging depths comparable to those from commercial systems for approximately one tenth the cost of a standard Ti:sapphire laser. This fiber laser is used to pump a diamond Raman laser to generate even longer wavelength light (1240 nm). Because the outputs from the fiber laser and the diamond Raman laser are synchronized, they allow for two-color multiphoton microscopy where two photons of different wavelengths are absorbed to excite fluorescence. Together these two lasers provide a significant increase in coverage of fluorophores excitable between 1000 to 1300 nm.