  Spectral filtering of resonance fluorescence is widely employed to improve
single photon purity and indistinguishability by removing unwanted backgrounds.
For filter bandwidths approaching the emitter linewidth, complex behaviour is
predicted due to preferential transmission of components with differing photon
statistics. We probe this regime using a Purcell-enhanced quantum dot in both
weak and strong excitation limits, finding excellent agreement with an extended
sensor theory model. By changing only the filter width, the photon statistics
can be transformed between antibunched, bunched, or Poissonian. Our results
verify that strong antibunching and a sub-natural linewidth cannot
simultaneously be observed, providing new insight into the nature of coherent
scattering.
