Qutronix developed a photon beam splitting system with complete intellectual property rights. We use multiple Fabry–Pérot cavities in cascade mode, assisted with appropriate auxiliary light paths, to achieve beam splitting operation for photons of different frequencies. We finally achieved both filtering and frequency division functions at the same time, especially suitable for ultra-fine spectrum analysis of weak light signals which exceeds the limit of traditional Dichroic Mirrors (DM). Furthermore, the spectrum accuracy and channel number of the instrument can be customized according to specific user requirements.