Abstract
We use the magnetic field distribution of an azimuthally polarized focused laser beam to excite a magnetic dipole transition in ions embedded in a nanoparticle. The absence of the electric field at the focus of an azimuthally polarized beam allows us to unambiguously demonstrate that the nanoparticle is excited by the magnetic dipole transition near 527.5 nm. When the laser wavelength is resonant with the magnetic dipole transition, the nanoparticle maps the local magnetic field distribution, whereas when the laser wavelength is resonant with an electric dipole transition, the nanoparticle is sensitive to the local electric field. Hence, by tuning the excitation wavelength, we can selectively excite magnetic or electric dipole transitions through optical fields.
- Received 20 November 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.163903
© 2015 American Physical Society