Wideband detection of transient solid-state dynamics using ultrafast fiber lasers and asynchronous optical sampling.

We demonstrate optical time-domain spectroscopy from femtoseconds to nanoseconds using an ultrafast dual-fiber-laser system with kilohertz continuous scanning rates. Utilizing different wavelengths for the pump and probe beams, we exploit this system's broad range of timescales for quantitative studies of thermal transport and the detection of coherent spin and lattice excitations in epitaxial magnetic thin films. The extraordinary temporal dynamic range provides a way to connect the fast and slow timescales in the observation of dissipation and decoherence processes.