Abstract
We describe advances inlight pulse sources using semiconductor lasers and focus on the recent progress
in light pulse generation and applications for multi-photon biomedical imaging. Studies on gain
switching under fast and intensive pulsed excitation revealed the potential of the reliable generation of
light pulses of a duration of several picoseconds. Combining gain-switched laser diodes (GSLDs) and
optical amplifiers, we experimentally produced compact, highly functional light pulse sources and
demonstrated that they enabled the world’s deepest in vivo multi-photon imaging of mouse brains. To
further extend LD functionality, wealso developed a method for producing smooth-shaped subnanosecond
light pulses utilizing a pulsed operation of a semiconductor laser amplifier instead of a
GSLD. This light pulse source will be used for very high performance pulsed-mode super-resolution
imaging. We also generated sub-picosecond light pulses with high-peak-power exceeding 1 megawatt
by removing spontaneous emission noise during light amplification. This technology will enable the
adoption of GSLDs for laser micro-processing applications.
