Chaos on lasers and masers discovered in 1964:

A. Z. Grasyuk and A.N. Oraevsky, Radio Eng. Electron. Phys. (USSR) 9, 924 (1964).

A. Z. Grasyuk and A.N. Oraevsky,"Transient processes in molecular oscillators," Radiotek, Elektron.9, 524-532 (1964)