A/Prof. Brant Gibson
Hybrid nanodiamond-doped photonic sensors
Fluorescent nanodiamonds (NDs) have a range of unique properties which make them highly desirable for solid system quantum applications. Their fluorescence is produced via optical excitation of atomic defects, such as the negatively charged nitrogen vacancy centre (NV), within the diamond crystal lattice. Possessing long-wavelength emission, high brightness, no photobleaching, no photoblinking, single photon emission at room temperature, nanometer size, biocompatibility, and an exceptional resistance to chemical degradation make NDs almost the ideal fluorescent nanoprobe. Furthermore, the NV defect has a spin-triplet ground state, within which its electronic spin can be polarised and read out optically at room temperature. I will discuss these exciting properties in detail and also give examples of ND integration with photonic materials for hybrid ND-photonic sensing applications.
The approach for combining NV quantum emitters [1,2] with photonic structures has been developed by embedding NDs into tellurite (TZN) glass, which is then drawn into fiber. This approach allows improved efficiency of the NV emitter to be coupled to a bound mode in the fiber  and significantly enhances device robustness. Tellurite glass was selected as the host material as it is liquid at relatively low temperatures (600-700 °C), which minimizes ND oxidation while enabling the NDs to be mixed into the glass melt . Tellurite glasses transmit light in the NV center excitation and emission wavelength range (500-800 nm), and have a high refractive index (n=2.0), which enhances the capture of the NV emission in the fiber core. In this work, the origin of loss in ND-doped tellurite glass was explored . Based on this understanding, the loss of ND-doped tellurite fibers was reduced by more than an order of magnitude down to 10 dB/m across the 600-800 nm wavelength range while preserving functional NDs in the glass . Using these optimised fabrication conditions, propagation of quantum information is being explored through ND-doped fibers as a backbone for remote hybrid diamond-photonic applications.
A/Prof. Gibson was awarded his PhD from La Trobe University in 2004. From 2004-05, he was a Research Fellow in the School of Physics at the University of Melbourne developing Ultra High Throughput Optical Probes for sub-diffraction limited microscopy. From 2005-09, A/Prof. Gibson was a Photonics Development Engineer at Quantum Communications Victoria (QCV) where he and colleagues designed and developed Australia’s first commercial quantum security product (QCV SPS 1.01). From 2009-11, A/Prof. Gibson was a Senior Research Fellow in Physics at The University of Melbourne and in 2011 he was awarded an ARC Future Fellowship on Hybrid Diamond Materials for Next Generation Sensing, Biodiagnostic and Quantum Devices. In July 2013, he commenced the position of Senior Lecturer at RMIT University in the School of Applied Sciences. A/Prof. Gibson is the RMIT Node Leader and a Science Theme Leader of the Australian Research Council Centre of Excellence for Nanoscale BioPhotonics.