We present experimental and numerical studies of nonlinear magneto-optical rotation (NMOR) in rubidium vapor excited with resonant light tuned to the $5^2!S_{1/2}rightarrow 6^2!P_{1/2}$ absorption line (421~nm). Contrary to the experiments performed
to date on the strong $D_1$ or $D_2$ lines, in this case, the spontaneous decay of the excited state $6^2!P_{1/2}$ may occur via multiple intermediate states, affecting the dynamics, magnitude and other characteristics of NMOR. Comparing the experimental results with the results of modelling based on Auzinsh et al., Phys. Rev. A 80, 1 (2009), we demonstrate that despite the complexity of the structure, NMOR can be adequately described with a model, where only a single excited-state relaxation rate is used.
We report on an all-optical magnetometric technique based on nonlinear magneto-optical rotation with amplitude-modulated light. The method enables sensitive magnetic-field measurements in a broad dynamic range. We demonstrate the sensitivity of $4.3t
imes10^{-9}$ G/$sqrt{text{Hz}}$ at 10 mG and the magnetic field tracking in a range of 40 mG. The fundamental limits of the method sensitivity and factors determining current performance of the magnetometer are discussed.
