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

Origins of propagation loss in diamond-doped optical fibers

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Description

Diamond particles containing nitrogen-vacancy (NV) centers enable fiber-based magnetic field sensing by allowing optical excitation and collection of NV fluorescence within an optical fiber. Tellurite glass is a promising host for NV-diamond particles because its refractive index (~2.0) is closer to that of diamond (~2.4) than most oxide and fluoride glasses, thereby reducing scattering at the glass-diamond interface. However, propagation loss remains a major limitation for diamond-doped fibers, with contributions arising from multiple fabrication and material related mechanisms.

In this work, tellurite fibers were fabricated to investigate the contributions of voids from incomplete glass fusion, diamond incorporation and refractive index contrast between host glass and diamond or voids on propagation loss. Propagation losses of an undoped tellurite fiber and a diamond-doped tellurite fiber with identical glass composition and fiber geometry were compared to quantify the additional loss introduced by diamond particles. An unstructured tellurite fiber fabricated from the same glass composition was used to estimate the contribution from void formation associated with the fiber fabrication process. In addition, a diamond-doped silicate glass fiber was investigated to uncover the influence of host glass refractive index on scattering loss by comparing the low-index silicate glass (n ≈ 1.6) with high-index tellurite glass (n ≈ 2.0).

The results show that void formation, diamond incorporation and host glass refractive index each make distinct contributions to propagation loss. Increasing the refractive index mismatch between the host glass and diamond particles results in higher scattering loss, while voids introduced during fiber fabrication contribute significantly to attenuation independently of the doped particles. Separating these loss mechanisms provides a clearer understanding of the factors limiting the performance of diamond-doped optical fibers and establishes a framework for developing lower-loss fibers for NV-based quantum sensing.