Pulse-to-pulse wavelength switchable fiber laser for multi-color two-photon excitation fluorescence (TPEF) microscopy

Non-linear bio-molecular imaging is a growing field with a strong demand for high power lasers. Especially two-photon excited fluorescence (TPEF) microscopy is a very promising and already widely applied imaging modality. The work horses for two-photon excitation are currently ultra-short pulse Ti:Sa lasers [1]. As these lasers tend to be bulky, expensive, and often not fiber compatible, there is a demand for new, easier to use, excitation sources. Hence, alternative approaches are investigated and recent studies [2-4] suggest that laser diode based all fiber light sources have a great potential to replace Ti:Sa lasers, at least for some TPEF fluorophores. However, a big drawback of these diode-based lasers is that they lack spectral flexibility as they operate at one wavelength only.