Modal gain characteristics of a two-section InGaAs/GaAs double quantum well passively mode-locked laser with asymmetric waveguide

Monolithic two-section InGaAs/GaAs double quantum well (DQW) passively mode-locked lasers (MLLs) with asymmetric waveguide, consisting of the layers of p-doped AlGaAs waveguide and no-doped InGaAsP waveguide, emitting at similar to 1.06 mu m, with a fundamental repetition rate at similar to 19.56 GHz have been demonstrated. Modal gain characteristics, such as a gain bandwidth and a gain peak wavelength of the MLL, as a function of the saturable absorber (SA) bias voltage (V-a) as well as the injection current of gain section (I-g), were investigated by the Hakki-Paoli method. With the increase of V-a, the lasing wavelength and net modal gain peak of the MLL both exhibited red-shifts to longer wavelength significantly, while the modal gain bandwidth was narrowed. Both the net modal gain bandwidth and gain peak of the MLL followed a polynomial distribution versus the reverse bias at the absorber section. In addition, for the first time, it was found that V-a had an obvious effect on the modal gain characteristics of the MLL.

Automated summary

This paper investigates the modal gain characteristics of InGaAs/GaAs double quantum well laser and finds that the bias voltage of the saturable absorber has a significant effect on the laser's wavelength and gain characteristics.