Spatio-Temporal Dynamics in the Near Field of a 980nm Ridge Waveguide Pump Laser Diode

The dynamic behavior of the light output from aluminum-free 980nm ridge waveguide GaInAs/GaInAsP/GaInP pump lasers is studied in the high power regime on a picosecond time scale. Three types of the temporal evolution of the turn-on emission dynamics measured by a single-shot streak-camera can be distinguished in the near field, according to the injection current. First, at moderate pumping, the laser emission evolves through a regime of relaxation oscillations, which can be modelled by rate equations incorporating nonlinear gain. Second, at a higher current, high frequency switching between the left and right part of the active region (ridge width is approx. 5μm) is observed. The frequency of the switching increases proportional to the excitation current amplitude and is in the order of 10GHz. The third regime shows highly complex spatio-temporal dynamics with the coexistence of low and high frequency spatial switching and temporal pulsations. Finally, consequences of the results for applications will be discussed.