Self-focusing and stimulated scattering of picosecond pulses in the active medium of an injection laser

Self-focusing and stimulated scattering of picosecond pulses in the active medium of a multisectioned Q-switched AlGaAs/GaAs heterolaser was observed for the first time. When the pulse power exceeded a certain critical value the distribution of the intensity on the end face of the laser split into two filaments of about 2 μm size. In the short-wavelength part of the optical spectrum of a train of picosecond pulses there were equidistant components separated by 56 ± 6 cm ^– 1 (7.0 ± 0.7 meV), which could be attributed to the interaction of ultrashort pulses with transverse acoustic phonons or with acoustic plasmons in GaAs.