Mode-locked operation characteristics of a monolithic integrated two-section InGaAs/GaAs double quantum wells laser with asymmetric waveguide

Abstract

We report on subpicosecond pulse generation using passively mode locked lasers (MLL) based on asymmetric waveguide with InGaAs/GaAs double quantum wells (DQW) passively mode-locked lasers (MLLs) grown in one epitaxial step. With systematic measurement of the performances of two-section MLLs, we found that the gain region current, absorber reverse bias voltage and operating temperature all have obvious modulation effects on the mode-locked frequency, line width, pulse width, emitting wavelength, and signal intensity of the MLL. Especially, the prepared device emitting at 1065.4 µm exhibited ∼396 fs of a pulse width at 12.155 GHz repetition rate, peak power of ∼1.25 W under an ideal time bandwidth product (TBWP) at 20 °C. To our knowledge, it is the best value ever reported for DQW MLLs. And we obtained that the pulse width increase caused by the temperature rise should be in the range of 6.5–11.4 fs/°C, also found that the heat accumulation or thermal effect in the reverse bias section has a key influence on MLL. This is of great significance for us to improve the performance of MLL.