Fourier Plane Optical Microscopy and Spectroscopy

Abstract

Intensity, wavevector, phase, and polarization are the most important parameters of any light beam. Understanding the wavevector distribution has emerged as a very important problem in recent days, especially at nanoscale. It provides unique information about the light–matter interaction. Back focal plane or Fourier plane imaging and spectroscopy techniques help to measure wavevector distribution not only from single molecules and single nanostructures but also from metasurfaces and metamaterials. This article provides a birds‐eye view on the technique of back focal imaging and spectroscopy, different methodologies used in developing the technique, and applications including angular emission patterns of fluorescence and Raman signals from molecules, elastic scattering, etc. We first discuss on the information one can obtain at the back focal plane of the objective lens according to both imaging and spectroscopy viewpoints and then discuss the possible configurations utilized to project back focal plane of the objective lens onto the imaging camera or to the spectroscope. We also discuss the possible sources of error in such measurements and possible ways to overcome it and then elucidate the possible applications.

Guide to optical spectroscopy of layered semiconductors

“…A very active field of research is devoted to incorporating TMD materials into photonic cavities, plasmonic and dielectric meta-surfaces 149 . These structures will affect the recombination dynamics but also change the emission direction, which can be investigated by Fourier plane imaging 150 . In this case, angular information on the light scattered from the sample can be collected.…”

Visualization of Directional Beaming of Weakly Localized Raman from a Random Network of Silicon Nanowires

“…So far, this occurrence has only been observed by means of angle resolved light scattering measurements. Previously, momentum‐space imaging had been employed for patterning the angular distribution of typical Raman bands in 2D materials, such as graphene, [ 52 ] in order to evaluate their polarization ratio or in plasmonic antennas [ 53 , 54 , 55 ] for estimating their degree of directional emission. In this work, we have further demonstrated the possibility of using Fourier imaging for tuning the directional beaming of coherent Raman light scattered by a random medium.…”

Directional Emission from Tungsten Disulfide Monolayer Coupled to Plasmonic Nanowire‐on‐Mirror Cavity

“…To transfer the Fourier plane from the back aperture of the objective lens to the EMCCD, 4f configuration is used. [ 55 ] High NA excitation ensures efficient excitation of surface plasmon in the NW as well as high electric field in the cavity. Combination of edge and notch filter has been used to efficiently reject the elastically scattered light.…”