A robust laser cavity platform for NV-diamond singlet infrared absorption magnetometry

Quantum Physics [Submitted on 21 Apr 2026] A robust laser cavity platform for NV-diamond singlet infrared absorption magnetometry Shao Qi Lim, Alexander A. Wood, Brett C. Johnson, Qiang Sun, Jan Jeske, Hiroshi Abe, Takeshi Ohshima, David J. Ottaway, Heike Ebendorff-Heidepriem, Robert E. Scholten, Andrew D. Greentree, Brant C. Gibson The negatively charged nitrogen-vacancy center (NV^-) in diamond is a versatile platform for quantum magnetometry under ambient conditions. Recently, laser threshold magnetometry (LTM) has been proposed as a means to significantly enhance the sensitivity of NV-based magnetometers by incorporating a diamond hosting NV^- centers within a laser cavity and operating near threshold. While demonstrations have validated the concept, practical implementations remain technically demanding, requiring high pump powers and precise alignment of free-space cavities. It remains unclear whether the benefits of operating near threshold will outpace increased laser noise. In this work, we integrate an NV-diamond with a high NV^- content into a compact external cavity diode laser and demonstrate singlet infrared absorption optically detected magnetic resonance (ODMR). The system exhibits exceptional threshold current stability, enabling ODMR using the threshold current as the read-out parameter. We report a five-fold enhancement in the ODMR contrast by operating near threshold. The best magnetic field sensitivity of 7.6~\mathrm{nT/\sqrt{Hz}} (DC-500 Hz) is achieved well above threshold, while near threshold sensitivity is limited by increased probe laser noise. These results establish a compact and mechanically robust platform for singlet absorption-based NV^- magnetometry and highlight key trade-offs between contrast enhancement and laser noise near threshold. Comments: 10 pages, 5 figures Subjects: Quantum Physics (quant-ph) Cite as: arXiv:2604.18937 [quant-ph]   (or arXiv:2604.18937v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.18937 Focus to learn more Submission history From: Shao Qi Lim PhD [view email] [v1] Tue, 21 Apr 2026 00:23:47 UTC (823 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)