Two-section passively Mode-locked laser as a test for amplification and absorption parameters of a quantum well based InP optical amplifier at 1300 nm

A quantum well based semiconductor optical amplifier (SOA) compatible with a butt-joint active passive integration scheme at 1300 nm is tested in a monolithic passively mode locked laser operating at 1300 nm. The different laser dynamics are investigated in detail and the gain and absorption parametrization of the SOA as used in a laser simulator is described. Simulation outcomes are compared with the characterization results of a passively mode-locked two-section laser that was realized using a fully active quantum well layer stack. The different laser dynamic regimes are identified by recording light intensity characteristics for a range of operating conditions with 50 GHz bandwidth in real time as well as the high frequency electrical spectra from a photodetector. Passive mode-locking has been achieved with a 20.4 GHz repletion rate with a 0.32% detuning of repetition rate by increasing the current, where a 0.25% detuning was predicted by the parametrized model. The stepped heterodyne technique has been used to measure the output pulse duration. A FWHM of 1.0 ps has been recorded after propagating for 110 m in standard single mode fiber. The phase spectrum with a maximum of 2.5 radians variation within the 6 nm frequency comb has been obtained. This value agrees with the simulation output, which models the amplification and the absorption out of this two-section laser. Q-switched mode-locking behavior is observed from the time traces. The measurements of the q-switching dynamics reveal a stepped behavior in the relaxation oscillations as function of current injected into the semiconductor optical amplifier, with the presence of an exotic dynamical system with different periodicities at the transition currents, that cannot be predicted by the model. The fit of the relaxation oscillation with the Q-switching self-pulsation frequencies, reveals a differential gain that is in-line with the parameter used in the simulations.