An example telemetry signal detection apparatus may include a optical splitter, a light source optically coupled to the optical splitter, and a light detector optically coupled to the optical splitter. The apparatus further may include a reference loop optically coupled to the optical splitter and a sensor loop optically coupled to the reference loop and the optical splitter. The reference loop may be contained within a reference loop enclosure. The sensor loop and reference loop may comprise a zero-area Sagnac loop with folded optical fiber or dual fiber cable configurations.