Experimental Comparison of Filter Integration Strategies for Nitrogen Vacancy Center Photoluminescence Detection in Optically Detected Magnetic Resonance Measurements

Optically detected magnetic resonance (ODMR) based on nitrogen‐vacancy (NV) centers in diamond is a powerful technique for sensing applications where the efficient detection of NV photoluminescence is a critical performance factor. Although optical filters are routinely employed to suppress the green excitation light, their integration at the detector level is often treated as a secondary design aspect. In this work, we present a systematic experimental comparison of different filter integration strategies applied directly to otherwise identical photodiodes and evaluate their impact on ODMR performance. The study was conducted using a breadboard ODMR setup comprising a green laser excitation source, a high‐pressure high‐temperature (HPHT) diamond containing NV centers with a concentration in the ppm range, microwave excitation, and lock‐in‐based signal detection. The filter variants were characterized using both ODMR contrast measurements at the NV − zero‐phonon line and optical density (OD) values extracted from laser power versus photocurrent measurements. Particular emphasis is placed on, showing that a higher OD does not always correlate with a higher ODMR contrast. We suggest that thin‐film filter approaches offer a favorable compromise between excitation suppression and ODMR signal quality, providing useful design guidance for NV‐center‐based sensing applications.