Ultrafast time-resolved spectroscopy of spin precession by an asynchronous optical sampling based on a dual-comb system

We developed an asynchronous optical sampling measurement (ASOPS) system based on a dual-comb fiber laser. This measurement system enables us to significantly accelerate a time-resolved measurement using the optical pump and optical probe method. We demonstrated the time-resolved measurement of laser-induced spin precession dynamics in a ferromagnetic permalloy thin film. The time resolution of the system was sub-picoseconds, the time window was 16 nanoseconds, and the overall measurement time was tens of seconds. This technique is expected to be useful for the temporal characterization of spin dynamics, taking advantage of high-speed measurement.