OD-FMR involves the application of a high-frequency microwave field to a ferromagnetic sample. This field induces precession of the magnetic moments within the material. The precession can be detected optically through changes in the material's magneto-optical properties, such as the Kerr effect or Faraday effect. A laser beam is typically used to probe these changes, and the resulting optical signal is analyzed to extract information about the magnetic dynamics.
