(Invited) Isolating an Individual Ion Emitter and Light-Induced Tunneling Upconversion

Abstract

This talk will review two recent discoveries made in my group. Single Photon Emitters: Intrigued by the promise of single-photon quantum technologies, many have studied the properties of single ion defect emitters, particularly lanthanides in a crystal matrix (including praseodymium, cerium, and erbium). I will report on a way of reliably isolating individual erbium ion emitters in nanocrystals with the potential for 100% individual emitter yield in post-selection. We used a nanoplasmonic (metal nanostructure) aperture optical tweezer to reliably isolate individual erbium ion emitters in individually trapped NaYF4 nanocrystals. The nanoplasmonic aperture solved two major problems: (1) it enhanced the emission rate so that single ions could be detected reliably in a short time, and (2) it isolated the single Er containing nanocrystal from the other nanocrystals in solution. This new demonstration follows our recently published work showing 400× increased emission using the nanoapertures. Light-Induced Upconversion Emission: Upconverted light from nanostructured metal surfaces can be produced by harmonic generation and multi-photon luminescence; however, these are very weak processes and require extremely high field intensities to produce a measurable signal. Here we report on bright emission, 5 orders of magnitude greater than harmonic generation, that can be seen from metal tunnel junctions due to light-induced inelastic tunneling. Like inelastic tunneling light emission, which was recently reported to have 2% conversion efficiency per tunneling event, the emission wavelength recorded varies with the local electric field applied; however, here the field is from a 1560 nm femtosecond pulsed laser source. Finite-difference time-domain simulations of the experimental conditions show the local field is sufficient to generate tunneling-based inelastic light emission in the visible regime. This phenomenon is promising for producing ultrafast upconverted light emission with higher efficiency than conventional nonlinear processes.