  There is a great desire to extend ultrasonic techniques to the imaging and
characterization of nanoobjects. This can be achieved by picosecond
ultrasonics, where by using ultrafast lasers it is possible to generate and
detect acoustic waves with frequencies up to terahertz and wavelengths down to
nanometers. In our work we present a picosecond ultrasonics setup based on
miniaturized mode-locked semiconductor lasers, whose performance allows us to
obtain the necessary power, pulse duration and repetition rate. Using such a
laser, we measure the ultrasonic echo signal with picosecond resolution in a Al
film deposited on a semiconductor substrate. We show that the obtained signal
is as good as the signal obtained with a standard bulky mode-locked Ti-Sa
laser. The experiments pave the way for designing integrated portable
picosecond ultrasonic setups on the basis of miniaturized semiconductor lasers.
