Superfluorescence in microrods and microfibers

Superfluorescence (SF) is a unique optical phenomenon that consists of an ensemble of emitters coupling collectively to produce a short but extremely intense burst of light. Despite our recently published works showing that room temperature anti-Stokes shifted SF were achieved in a few randomly assembled or even single lanthanide-doped upconversion nanoparticle (UCNP), the coupling required to produce and optimize Burnham-Chiao ringing (echoing of pulses) is not understood. Such ringing could be particularly useful to provide timing and multiplexing in potential applications as an alternative light source device. We previously found a lack of Burnham Chiao ringing in single nanocrystals, but strong ringing in a random cluster. The ordered assembly of these crystals will not only create a SF superburst, but also enable understanding of the periodicity of the Burnham Chiao ringing. This work explores SF microrod (MR), with enhanced SF performance and the closely spaced assembly of MR result in a greater active volume, which gives rise to greater reabsorption of the initial emission, which is then re-emitted, leading to greater oscillatory fluorescence or Burnham Chiao ringing. We also correlate the MR dimension and orientation with the corresponding SF spectral properties.