Probing Ultrafast Switch-on Dynamics of Frequency Tuneable Semiconductor Lasers Using Terahertz Time-domain Spectroscopy

We report measurements of switch-on dynamics, mode competition and frequency selection in a monolithic frequency-tuneable laser using coherent time-domain sampling of the laser emission. We observe hopping between lasing modes on picosecond-timescales and temporal evolution of transient multi-mode emission into steady-state single mode emission.