Working with single nano-antennas and single quantum emitters directly implies a strong interest in nanoscopy, and nano-manipulation. Questions one immediately ask are for instance: how do you select an excellent emitter on basis of its photophysical properties, how do you position one object relative to the other via chance, lithography, or nanomechanical manipulation, and what are the scattering properties of single objects. A workhorse tool in our group is single molecule fluorescence microscopy. Using state of the art methods, one can nowadays measure the spectrum and lifetime of a single emitter within 10 ms, meaning that one can really follow changes in photophysics in time (missing reference). Superresolution and NSOM techniques can be used for localizing single objects relative to each other. In our work, we focus on applying such techniques to light-matter interaction problems. Examples are measuring Purcell factors as function of spatial coordinate with superresolution [88], measuring the intrinsic quantum efficiency of single emitters [57], [61], and measuring emission properties while you make geometrical changes to a resonant nanostructure [59].

### Fourier microscopy - mapping radiation patterns in amplitude, vector and phase (Stokes polarimetry):

Resolving angles in microscopy is at least as informative as resolving space. What is the distribution of scattering or of photon emission over angle? In the fields of plasmonics and metamaterials, intuition very often relies on classifying a structure as a dipole, multipole, magnetic moment, as having chiral contributions, or as being a coherent interfering sum of terms. Quantifying this intuition is difficult as one can not actually measure induced multipole moments. Alternatively, one can measure the amplitude, polarization, and phase-properties of the light that a single nano-objecct emits or radiates into each solid angle. In principle this is sufficient information to reconstruct all the near-field properties. We use so-called `Fourier’ microscopy [42], mapping the angular distribution of light directly on a camera to quantify radiation patterns and polarization [74], [82]. We apply this method to plasmon antennas that beam fluorescence in a specific direction, to plasmon lattice phosphors and lasers [69], [91], and to antennas that impart chirality, and orbital angular momentum, to emitted light [87].

[91] | A. H. Schokker and A. F. Koenderink, , Optica Lasing in Quasi-Periodic and Aperiodic Plasmon Lattices3, 686–693, (2016). |
(p)reprint DOI |

[88] | K. Guo, M. A. Verschuuren, and A. F. Koenderink, , Optica Superresolution Imaging of the Local Density of States in Plasmon
Lattices3, 289–298, (2016). |
(p)reprint DOI |

[87] | M. Cotrufo, C. I. Osorio, and A. F. Koenderink, , ACS Nano Spin-Dependent Emission from Arrays of Planar Chiral Nanoantennas Due To
Lattice and Localized Plasmon Resonances10, 3389–3397, (2016). |
(p)reprint DOI |

[82] | A. Mohtashami, C. I. Osorio, and A. F. Koenderink, , Phys. Rev. Appl. Angle-Resolved Polarimetry of Antenna-Mediated Fluorescence4, 054014, (2015). |
(p)reprint DOI |

[74] | C. I. Osorio, A. Mohtashami, and A. F. Koenderink, , Sci. Rep. K-Space Polarimetry of Bullseye Plasmon Antennas5, 9966, (2015). |
(p)reprint DOI |

[69] | A. H. Schokker and A. F. Koenderink, , Phys. Rev. B Lasing at the Band Edges of Plasmonic Lattices90, 155452, (2014). |
(p)reprint DOI |

[61] | P. Lunnemann, F. T. Rabouw, R. J. A. van Dijk-Moes, F. Pietra, D. Vanmaekelbergh, and A. F. Koenderink, , ACS Nano Calibrating and Controlling the Quantum Efficiency Distribution Of
Inhomogeneously Broadened Quantum Rods by Using a Mirror Ball7, 5984–5992, (2013). |
(p)reprint DOI |

[59] | M. Frimmer and A. F. Koenderink, , Phys. Rev. Lett. Spontaneous Emission Control in a Tunable Hybrid Photonic System110, 217405, (2013). |
(p)reprint DOI |

[57] | M. Frimmer, A. Mohtashami, and A. F. Koenderink, , Appl. Phys. Lett. Nanomechanical Method to Gauge Emission Quantum Yield Applied To
Nitrogen-Vacancy Centers in Nanodiamond102, 121105, (2013). |
(p)reprint DOI |

[42] | I. Sersic, C. Tuambilangana, and A. F. Koenderink, , New. J. Phys. Fourier Microscopy of Single Plasmonic Scatterers13, 083019, (2011). |
(p)reprint DOI |