Photonic ATM switching systems with Terabit/s throughput are desirable for future broadband ISDN systems. Since electronic LSI-based ATM switching systems are planned to have the throughput of 160Gb/s, a photonic ATM switching system should take the role of the highest layer in a hybrid switching network which includes electronic LSI-based ATM switching systems as its sub-system. This report discusses the state-of-the-art photonic devices needed for a frequency-self-routing ATM photonic switching system with maximum throughput of 5Tb/s. This kind of systems seems to be a moderate system for the first phase photonic switching system with no insuperable obstacle for initiating development, even though none of the devices and technologies required have yet been developed to meet the specifications. On the contrary, for realizing further enlarged throughput as the second-phase photonic switching system, there are huge fundamental research projects still remaining for establishing the technology utilizing the spectrum broadened over 120nm and highly-dense FDM technologies based on homodyne coherent detection, if supposing a simple architecture. "Ultra devices" seem to be the photonic devices based on new tailored materials of which gain and refractive index are designed to realize ultra-wide spectrum utilization.