Detection of local electron and nuclear spin dynamics by time-resolved Kerr microscopy

We implement time-resolved Kerr microscopy (TRKM) system with ∼1μm spatial resolution for observation of coupled electron–nuclear spin dynamics such as dynamic nuclear polarization (DNP) in a local area of the laser spot. From TRKM measurements, Larmor precession of electron spins injected by right (σ+)(σ+) or left (σ−)(σ−) circular polarized pump pulse is detected. The difference of the precession frequencies between σ+σ+ and σ−σ− pumping corresponds to the polarization-dependent nuclear magnetic field caused by DNP. This indicates that we successfully detect coupled electron–nuclear spin dynamics in a local area of the laser spot size of ∼1.5×1.5μm2. Furthermore, we show the pump and probe power dependences of DNP in high optical intensity region. All-optical NMR is also demonstrated at arbitrary frequencies by controlling acousto-optical modulator.