2026/08/03 by Tobias Probst, Florian Schall, Sebastian Heuft +9
Physics and Astronomy · #quant-ph #cond-mat.mtrl-sci #physics.app-ph #physics.optics
8 pages, 5 figures
arxiv created 2026/08/03 · arxiv updated 2026/08/04
Magnetometry with nitrogen-vacancy (NV) centers in diamond has shown great promise in recent years. In particular, absorption-based magnetometry techniques, employing a cavity to enhance the absorption length, can improve the contrast and sensitivity compared to conventional techniques based on reading out the NV- triplet fluorescence. The absorption techniques rely on magnetic-field-dependent absorption at the NV- singlet zero phonon line at 1042 nm and its phonon sideband. In a cavity-enhanced spectroscopy approach, we study pump-laser- and microwave-induced cavity signal changes at room temperature over a spectral range of 680-1050 nm. Through normalization, we eliminate the cavity-enhancement effect and provide quasi-single-pass values for the absorption and optically detected magnetic resonance (ODMR) contrast. The highest contrast is found at 1042 nm, but multiple points of high contrast are found at the peaks of the phonon sideband. Additionally, cavity-enhanced ODMR contrasts in the range of 50-80 % are presented. We further measure the broadband singlet absorption cross section at room temperature with a novel method through microwave-induced signal changes. This method is insensitive to pump-laser-induced signal changes by other defects and quantifies the room-temperature absorption strength of the singlet transition and its entire phonon sideband. We determine the absorption cross section at 1042 nm to be σ \bigstar1042=(0.89±0.14)⋅ 10-21 m2 or σ \blacktriangle1042=(2.9±0.5)⋅ 10-21 m2. depending on the employed 532 nm NV- absorption cross section.