26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Doping Optical Fibres with NV-diamonds for Magnetic Field Sensing

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Speaker

Jacob Dalgleish (Adelaide University)

Description

Nitrogen-vacancy (NV) centres in diamond are prominent quantum defects that have attracted significant interest for sensing applications, particularly room-temperature magnetometry. Their optical and spin properties, with excitation at ~532 nm and emission spanning 600–800 nm, make them well suited for integration into optical systems. Embedding NV-diamonds within optical fibres enables compact, robust photonic platforms capable of remote operation in challenging environments, including liquid immersion and other inaccessible locations.

Several fabrication strategies have been developed to integrate NV-diamonds into glass fibres, each presenting distinct advantages and trade-offs in optical performance and device functionality. Direct incorporation into the molten glass during fibre fabrication produces a uniform distribution of diamonds throughout the fibre, enabling distributed sensing but limiting spatial selectivity. Interface doping, in which glass preforms or rods are dip-coated with an ethanol-based NV-diamond suspension prior to fibre drawing, confines the diamonds to the fibre core, improving overlap with the guided optical mode and enhancing collection efficiency. Splice doping, achieved by attaching diamonds to a fibre end-face before fusion splicing, creates highly localized sensing regions suitable for point measurements. Together, these approaches demonstrate the balance between fabrication complexity, optical coupling, and spatial resolution in the design of NV-diamond fibre devices.

The sensing functionality of these fibres is realised using techniques such as optically detected magnetic resonance (ODMR), which exploits the spin-dependent optical response of the NV centre. Under green optical excitation, resonant microwaves drive transitions from the ms = 0 ground state to the magnetically split ms = ±1 states. The resulting increase in non-radiative decay reduces the NV photoluminescence, enabling precise measurement of the local magnetic field. By combining established fibre fabrication methods with the unique quantum-optical properties of NV centres, fibre-integrated NV-diamond devices provide a versatile platform for both localized and distributed magnetometry.