Q-switched and mode-locked lasers for biophotonic applications

We have attempted an overview of fast-pulsating lasers (gain-switched, Q-switched and mode-locked) in various biomedical applications. By necessity, the accents in the chapter have been to an extent coloured by our research experience and interests; apologies are extended to those authors whose work may have been omitted. Different properties of a laser system are important for different applications (e.g., high instantaneous and average power for multiphoton spectroscopy vs. spectral tuning range for OCT), but all the designs above benefit from the properties of semiconductor lasers such as chip compactness, ease of pumping, and high gain per unit length. The use of nanostructures, particularly QDs, has been shown to open new exciting opportunities.