A route to erbium-doped nanocrystals as a single photon source using double nanohole optical tweezers
Date
2022-04-28
Authors
Dobinson, Michael
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Abstract
This thesis presents a route towards a single photon source based on erbium-doped
nanocrystals, fabricated with methods that use double nanohole optical tweezers.
Single photon sources are an exciting quantum technology and erbium is good candidate
as it emits in the low-loss fiber optic C-band, but it is a weak emitter. Double
nanohole apertures can be designed with plasmonic resonances to enhance the local
electric field. In this thesis, double nanohole optical tweezers are used to isolate
and enhance the emission of erbium-doped nanocrystals, with the tuned geometry
showing a factor of 50 additional enhancement over rectangular apertures. With
the enhanced emission, nanocrystals with discrete levels of erbium emitters are detected
and isolated in real-time, based on their level of emission. This real-time process
demonstrates a major improvement over typical post-processing approaches.
A novel method to anchor nanocrystals in a double nanohole using a photochemical
thiol reaction was investigated which yielded 40% of nanoparticles anchoring
within 2 μm of the DNH, with 5% inside. This is useful as otherwise the
trapping laser must be maintained to keep the nanocrystal in the trap. Another
challenge is coupling to an optical fiber, for which a method to combine trapping
and coupling was explored. Colloidal pattern transfer is presented as a low-cost
fabrication method for nanoaperture optical fiber tweezers, with fiber-based trapping
demonstrated using 40 nm polystyrene nanospheres and hexagonal boron
nitride. The preliminary results from these methods show great potential, and
with further refinement they may lead towards a method to fabricate a low-cost
fiber-coupled single photon source based on erbium-doped nanocrystals.
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Keywords
optical trapping, nanoaperture, single emitter