Numerical investigation of 1550 nm passively mode-locked diode lasers with different gain and absorber configurations

In this study, passively mode-locked semiconductor lasers with a central wavelength of 1550 nm are theoretically investigated, consisting of gain and absorption sections. Variation of carrier density with time and pulse profiles of the laser outputs are obtained. Comparative results are obtained for different lengths of the gain sections and absorber sections. In addition, the results are also examined while the absorption section is located between two gain sections and at the far end. It has been found that the devices with two gain sections have higher power and shorter pulse width when the absorber section is located between the two gain sections. Finally, ultrashort stable optical pulses with nearly 800 mW peak power and 1.57 ps duration have been obtained from mode-locked laser diodes with two gain sections and one absorber section located between.