A time-resolved Faraday rotation magnetometer using externally triggered pulsed diode lasers is described. This device permits measurement of the dynamic properties of polarized electronic spins in semiconductors. A nonequilibrium spin polarization is created in the conduction band electrons of -type GaAs using a circularly polarized laser pulse generated by a pulsed laser diode. A subsequent linearly polarized pulse from a second laser diode probes the time evolved electronic polarization via the Faraday effect. Since two different laser diodes are used for the pump and probe process, the dynamics of optically pumped spins can be directly observed at arbitrarily long pump–probe delays with a temporal resolution of and a spatial resolution of . The signal-to-noise of the laser diodes is sufficient to achieve a sensitivity on the order of 3000 spins.
REFERENCES
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