Nonlinear Magneto-Optical Rotation with Amplitude-Modulated Light: AMOR
  A new technique of nonlinear magneto-optical rotation with amplitude modulated light is developed. The technique is an alternative to its counterpart with frequency modulated light and can be applied to sensitive measurements of magnetic fields ranging from microgauss to the Earth-field level. The rotation signals exhibit nontrivial features like narrowed non-Lorentzian lineshapes and multi-component resonances. 
W. Gawlik, L. Krzemien, S. Pustelny, D. Sangla, J. Zachorowski, M.   Graf, A.O. Sushkov, D. Budker