@Lup Yuen Lee 李立源 We send data via light often times except we seldom see it as such. Infrared remote controls send data back and forth every time they're used. I remember once having a laptop which had an infrared port, which I'd use to sync my Palm Pilot back in the way back time.
Back in maybe 1998 our office printer by HP had an infrared port, and the Pentium II laptop had that too. A fast data transfer that was not, but got the work done.