Currently deployed fiber and free-space optical communication systems use on-off keying (OOK) with direct detection, and some are beginning to use differential phase-shift keying (DPSK) with interferometric detection. Wave propagation is guided by optical fibres. Co pared to twisted pair and coaxial cable, it has a greater bandwidth efficiency. Therefore, certain characteristics of light (such as brightness and vibration state) need to be adjusted. Fiber optic communication has expanded significantly in the fields of data transmission and communication engineering in the modern communication environment.