Abstract

An azimuthally electric-polarized vector beam (APB), with a polarization vortex, has a salient feature that it contains a magnetic-dominant region within which the electric field is ideally null while the longitudinal magnetic field is maximum. Fresnel diffraction theory and plane-wave spectral calculations are applied to quantify field features of such a beam upon focusing through a lens. The diffraction-limited full width at half-maximum (FWHM) of the beam’s longitudinal magnetic field intensity profile and complementary FWHM of the beam’s annular-shaped total electric field intensity profile are examined at the lens’s focal plane as a function of the lens’s paraxial focal distance. Then, we place a subwavelength dense dielectric Mie scatterer in the minimum-waist plane of a self-standing converging APB and demonstrate for the first time, to the best of our knowledge, that a very-high-resolution magnetic near-field at optical frequency is achieved with total magnetic near-field FWHM of 0.23λ (i.e., magnetic near-field spot area of 0.04λ2) within a magnetic-dominant region located one radius (0.12λ) away from the scatterer. In particular, the utilization of the nanosphere as a magnetic nanoantenna (so-called magnetic nanoprobe) illuminated by a tightly focused APB is instrumental in boosting the photoinduced magnetic response and suppressing the electric response of a sample matter. The access to the weak photoinduced magnetic response in sample matter would add extra degrees of freedom to future optical photoinduced force microscopy and spectroscopy systems based on the excitation of photoinduced magnetic dipolar transitions.

© 2016 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Nonparaxial and paraxial focusing of azimuthal-variant vector beams

Bing Gu and Yiping Cui
Opt. Express 20(16) 17684-17694 (2012)

Magnetization shaping generated by tight focusing of azimuthally polarized vortex multi-Gaussian beam

Weichao Yan, Zhongquan Nie, Xueru Zhang, Yuxiao Wang, and Yinglin Song
Appl. Opt. 56(7) 1940-1946 (2017)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (17)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (32)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Metrics

You do not have subscription access to this journal. Article level metrics are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription