Space has unique conditions such as zero gravity and the thermal environment.　It's completely different from the terrestrial environment and it's a world where our common sense doesn't work. However, it makes us realize what we have not achieved on earth. Somehow space attracts us a lot. Optical communication has spread because people have studied and developed. Also, the optical communication devices and systems have been developed and they are expected to be used in space, too. We are making efforts in the development for the free-space optical communication in space and the stratosphere. in the case of the terrestrial optical communication, it is necessary to use optical fibers for long-distance and high-performance data networking. However, using the free-space optical communication in space the large capacity and high bandwidth network services can be provided without the optical fibers. Therefore, it could be possible to provide optical communication to the disconnected area affected by disaster and developing countries. As an optical engineer, I contribute to building a new optical communication system in space and the stratosphere.

[Keywords] Space ／ Stratosphere／ Satellite／ Free-space Optical Communication／ Optical Fiber Communication／ Optical Device／ Laser