技術摘要（英）
The present invention is a photoelectric sensing device, which includes a diffusion film for introducing the light to be measured, a filter element with a plurality of coating layers to filter a detection light beam from the light to be measured, and a sensing circuit for sensing the detection light beam. The dual-band sensing function can be provided by the photoelectric sensing device. In addition, a system with the photoelectric sensing device and an operating method thereof are also disclosed in the present invention, wherein secondary light coupling elements couple the plurality of incident light into a first coupling light, and a main light coupling element couples the first coupled light into a second coupling light, and a fluorescent light is formed from part of the second coupled light when passing through an erbium-doped fiber. A first photoelectric sensing device and A second photoelectric sensing device are respectively arranged on the secondary light coupling element and the erbium-doped fiber to monitor the state of blue laser and the fluorescent light respectively, so as to provide real-time monitoring effect.