Increase in the Efficiency of a Tandem Semiconductor Laser–Optical Amplifier Based on Self-Organizing Quantum Dots

Rate equations are used to analyze the characteristics of a tandem device consisting of a laser diode and a semiconductor optical amplifier made of a single heterostructure with quantum dots. The optimal value of the current-distribution coefficient between the amplifier and the laser, as well as the optimal cavity length that provides the highest output power of the tandem device are determined. It is shown that the use of the tandem device allows, at the same total consumed current, a significant (more than 4 times for 1 A) increase in the power emitted through the ground-state optical transition in comparison with that achievable with a laser diode solely being limited by the onset of lasing through the excited-state optical transition.