Abstract
We demonstrate a nanotip electron source based on a graded index multimode silica optical fiber, tapered at one end to a radius of curvature r ∼50 nm and coated with a thin film of gold. We report observation of laser-induced electron photoemission at tip bias potentials below the onset of dark field emission. Single-photon photofield emission is identified as the emission mechanism that exhibits fast switching times with an upper limit on the order of 1 μs. The explored fiber optic nanotips are flexible back-illuminated emitters, which can be operated in continuous wave and pulsed modes using lasers with photon energies in the visible range or higher. The mechanical flexibility of the source can facilitate externally controlled positioning. Multiple, individually addressable, nanotips may be assembled into a bundle for applications such as computational electron ghost imaging.
Original language | English |
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Article number | 061102 |
Journal | Applied Physics Letters |
Volume | 117 |
Issue number | 6 |
DOIs | |
State | Published - Aug 10 2020 |
Funding
A. Passian acknowledges support from the Laboratory Directed Research and Development Program at the Oak Ridge National Laboratory (ORNL). ORNL is managed by UT-Battelle, LLC, for the U.S. DOE under Contract No. DE-AC05-00OR22725. The fiber optic probes were fabricated at ORNL. S. Keramati and H. Batelaan acknowledge support from a UNL Collaborative Initiative grant and from the National Science Foundation (NSF) under Award Nos. EPS-1430519 and PHY-1912504. The SEM images were taken at the NanoEngineering Research Core Facility (NERCF), which was partially funded by the Nebraska Research Initiative. We thank Dr. P. Lougovski at ORNL for useful discussions. S. Keramati would like to thank Dr. C. Uiterwaal for helpful discussions.