摘要： The dynamic polarization of nuclear spins interacting with resident electrons under resonant excitation of trions is studied in a nominally undoped GaAs/(Al,Ga)As quantum well. Unlike in common time-resolved pump-probe techniques, we used a single-beam approach in which the excitation light is modulated between the circular and linear polarization states. The time-integrated intensity of the excitation laser re?ected from the sample surface, proportional to the optical generation rate and changing due to the pumping of the resident electrons, is detected. Polarized electrons, on the other hand, transfer their spin to the lattice nuclei via the hyper?ne interaction. Exciting the sample with a train of pulses in an external magnetic ?eld leads to resonant spin ampli?cation observed when the Larmor precession frequency is synchronized with the laser pulse repetition rate. A buildup of the nuclear spin polarization causes a shifting of the resonant spin ampli?cation peaks since the resulting nuclear ?eld alters the strength of the external magnetic ?eld experienced by the electrons. It was established that the nuclear spin polarization time T1 is temperature dependent and, owing to the electron localization at lower temperatures, becomes shorter. “Locking” of the nuclear (Overhauser) ?eld in the oblique external magnetic ?eld, related to the anisotropy of the electron g factor, was observed. The g factor ratio between the in-plane (g(cid:2)) and out-of-plane (g⊥) components was estimated to be g⊥/g(cid:2) = 1.3.