Background: Weak measurement involves weak coupling between the system
and the measuring device (pointer) enables large amplification and high precision
measurement of small physical parameters. The outcome of this special measurement
procedure involving nearly mutually orthogonal pre- and post-selection of states in such
weakly interacting systems leads to weak value that can become exceedingly large and lie
outside the eigenvalue spectrum of the measured observable. This unprecedented ability of
weak value amplification of small physical parameters has been successfully exploited for
various metrological applications in the optical domain and beyond. Even though it is a
quantum mechanical concept, it can be understood using the classical electromagnetic
theory of light and thus can be realized in classical optics.
Objective: Here, we briefly review the basic concepts of weak measurement and weak value
amplification, provide illustrative examples of its implementation in various optical domains.
The applications involve measuring ultra-sensitive beam deflections, high precision
measurements of angular rotation, phase shift, temporal shift, frequency shift and so forth, and
expand this extraordinary concept in the domain of nano-optics and plasmonics.
Methods: In order to perform weak value amplification, we have used Gaussian beam and
spectral response as the pointer subsequently. The polarization state associated with the
pointer is used as pre and post-selection device.
Results: We reveal the weak value amplification of sub-wavelength optical effects namely
the Goos-Hänchen shift and the spin hall shift. Further, we demonstrate weak measurements
using spectral line shape of resonance as a natural pointer, enabling weak value
amplification beyond the conventional limit, demonstrating natural weak value
amplification in plasmonic Fano resonances and so forth. The discussed concepts could
have useful implications in various nano-optical systems to amplify tiny signals or effects.
Conclusion: The emerging prospects of weak value amplification towards the development
of novel optical weak measurement devices for metrological applications are extensively