We report on the development of monolithic two-section dilute nitride passively mode-locked ridge-waveguide lasers. The dilute nitride material system can cover a wide wavelength range from 1.2 μm to 1.6 μm, while enabling fabrication on low-cost GaAs substrates. The laser structure comprised 3 GaInNAs quantum wells embedded within GaAs waveguide and AlGaAs claddings. To achieve mode-locking at 40 GHz repetition rate the laser chips consisted of a 950 μm long gain section and a 90 μm long reverse biased absorber section with a ridge width of 3.5 μm. The mode-locked laser output exceeded 3 mW per as-cleaved facet with 80 mA current in the gain region and a reverse voltage of 3.8 V applied to the saturable absorber. The corresponding pulse width was 3.4 ps. To study the effect of increasing the number of N-related recombination traps present in the proximity of the quantum wells, we have compared the performance of lasers employing GaAsN or GaAs as quantum well barriers. Time-resolved photoluminescence measurements revealed that the material comprising GaAsN barriers exhibited a photoluminescence lifetime of 12 ps with a reverse bias of 5 V. For similar reverse bias, the photoluminescence lifetime for material comprising GaAs barriers was 108 ps.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.