Experiment plan for a small optical transponder onboard a 50 kg-class small satellite

50 kg-class satellites can reduce production cost and time compared to larger satellites. On the other hand, the communication capacity in radio frequency for 50 kg-class satellites is limited, however it can be improved by using optical communications. The National Institute of Information and Communications Technology (NICT) has begun to develop a Small Optical TrAnsponder (SOTA) onboard a 50 kg-class satellite, which project is called the Space Optical Communications Research Advanced Technology Satellite (SOCRATES). We will introduce the experiment plan for SOTA onboard the 50 kg-class small satellite.