Features of mode locking in laser with quantum well in broad waveguide layer

Passive mode locking (PML) regimes in two-section lasers with quantum wells in broad waveguides operating at λ = 1.06 μm have been studied. The room temperature spectrum of the saturable absorber section retains exciton peak at the absorption edge, which decreases in amplitude shifts toward longer wavelengths by 18 meV when the reverse bias voltage is varied from 0 to 14 V. The PML regime is observed at relatively large voltages (above 9 V) that are necessary to compensate for the effect of band broadening in the gain section by the Stark shift of absorption in the reversely biased section. The PML regime exists, beginning with threshold values of the pumping current, and is characterized by a narrow RF signal with a 20-kHz linewidth. As the reverse bias voltage on the absorber section is increased, a low-frequency amplitude modulation superimposes on the mode-locked laser radiation.