Microdiamond-doped lead-silicate glass optical fibre for remote magnetometry

We demonstrate fabrication and characterizations of intrinsically magneto-sensitive fiber with potential applications as a high-efficiency remote magnetic field sensing platform. The fibre was fabricated using lead-silicate glass and the rod-intube fibre drawing technique. The thin glass rod of ∼1 mm diameter was first coated with nitrogen-vacancy (NV) centreenriched diamond particles of ∼1 μm diameter, and subsequently inserted into the glass outer tube. This rod-in-Tube assembly was drawn down to fibre, with the diamond particles distributed at the fused interface between rod and tube. We experimentally coupled 532 nm continuous-wave laser into a 30-cm-length fibre piece from the fibre endface, and examined the photoluminescence (PL) properties of the fibre from both the side of the fibre and the output end of the fibre. PL mapping results showed that the glass-embedded NV emitters showed bright and photostable fluorescence, demonstrating characteristic NV centre zero phonon line emission. Moreover, the mapping result obtained at the output end of fibre indicated that the transmitted NV fluorescence was coupled into the propagation modes of the fibre. By using optically detected magnetic resonance (ODMR) from the NV ensemble along the fibre, we demonstrate detection of local magnetic fields via longitudinal excitation and side collection. Based on the current light transmission and collection configuration, the hybrid diamond-glass optical fibre sensor demonstrated a shot noise-limited DC magnetic field sensitivity of 3.7 μT/√Hz at room temperature. Our results open the possibility of robust, field-deployable fibre optical magnetometry.