All possible unauthorized accesses to fiber-optic communication systems were analyzed, and destructive, non-destructive, and optical-radio wave methods of data collection were considered. An optoelectronic method for countering unauthorized data collection and modern technical means for unauthorized data collection in fiber-optic communication systems was developed. An optoelectronic device implementing an optoelectronic method for countering unauthorized data collection and modern technical means for unauthorized data collection in fiber-optic communication systems was developed.