One embodiment includes a nuclear magnetic resonance (NMR) gyroscope system. The system includes a vapor cell comprising an alkali metal and a plurality of gyromagnetic isotopes and a pump laser configured to generate an optical pump beam configured to spin-polarize the alkali metal. The system also includes a probe laser that generates an optical probe beam and a detection system configured to monitor the optical probe beam and to calculate a rotation of the NMR gyroscope system about a sensitive axis based on a modulation of the optical probe beam in response to precession of the plurality of gyromagnetic isotopes resulting from the spin-polarization of the alkali metal. The system further includes a calibration controller that modulates a characteristic of the optical pump beam to substantially mitigate bias errors associated with the gyromagnetic isotopes in the calculation of the rotation of the NMR gyroscope system about the sensitive axis.