Geon is a terrestrial silicon single-photon detector (SPD) intended for laboratory and ground-based quantum systems. Covering a 300–1000 nm wavelength range, it offers high photon detection efficiency, low dark counts, and adjustable operating parameters such as dead time, output pulse width, and saturation level. With nanosecond timing jitter and TTL output, Geon supports applications including quantum optics experiments, photon counting, calibration tasks, and educational or research setups. Its compact enclosure and standard SMA output make it suitable for bench-top use and system integration in terrestrial quantum laboratories.