Abstract: Strong backlighting and complex background interference are the critical factors that restrict the sensitivity and imaging quality of optical detection systems. Traditional interference filters are limited by nanometer-scale bandwidth and sensitivity to environmental parameters, making it difficult to achieve effective suppression under strong background and weak signal extraction from complex and dynamic scenes. Atomic filters utilize the selective absorption and dispersion characteristics near atomic resonance transitions to achieve ultra-narrowband, high transmittance, and high extinction ratio filtering, providing a new path at the physical mechanism level for overcoming the bottleneck in backlight detection. To systematically elucidate the core mechanism and technological advantages of atomic filters in backlight detection, this paper reviews the basic principles of their strong background suppression, focuses on the key progress of atomic filtering technology, represented by Faraday atomic filters, in laser communication, extreme condition imaging, and lidar in recent years, analyzes the main challenges faced by the current technical route, and looks forward to its development prospects in weak signal detection and precision measurement, with the aim of providing a reference for the research and development of high-sensitivity optical detection systems under complex background conditions.