LAUSR

In this study, the authors present experimental results on 6 mm long monolithic passively colliding-pulse mode-locked (CPM) lasers. The AlGaAs-based devices with In x Ga1−x As y P1−y double-quantum-well (DQW) active regions emit between 860 and 880 nm. To optimise the laser performance and to shorten the pulses the optical gain is spectrally broadened to increase the number of longitudinal lasing modes by using a chirped DQW structure where the In-content of the QWs differs by Δx = 0.08. Lasers having the chirped DQW with lasers having a conventional, unchirped DQW active region are compared. The mode locking operation is investigated in dependence on gain current, absorber voltage and absorber length. According to the experimental results, the lasers with the chirped DQW exhibit an overall better performance and generate shorter pulses with higher average optical output powers over a wider range of parameters. For an optimum set of parameters, the generated pulses have a full width at half maximum of the autocorrelation function of 1.9 ps at a repetition frequency of 12.9 GHz.