Spectroscopic imaging for characterization of metal-enhanced upconversion

We use a custom built spectrally-resolved confocal microscopy system to investigate the enhanced near infrared to visible upconversion produced in NaYF₄:Er_.03:Yb_.17 nano-crystals. We examine the spatial variations in the intensity and spectral variations in the near infrared to visible upconversion due to thin films of NaYF₄:Er_.03:Yb_.17 nano-particles embedded in PMMA, supported on Au and Ag metallic nano-structured substrates, including randomly distributed Ag nanowire monolayers and Au nano-pillar arrays fabricated by electron beam lithography. Spectrally-resolved imaging provides a massively parallel means of assessing the range of achievable enhancement and its relation to the specific configuration of the substrate / upconverting nano-particle system. A statistical analysis of the images obtained provides the average and extremes of the enhancement, and can be used as a guide to engineer coatings and / or substrates with optimal properties.