Nick Holonyak, Jr. invented the first visible-spectrum light-emitting diode.

Nick Holonyak, Jr. first began work on the visible-spectrum light-emitting diode in 1960 while working at General Electric. He had discovered that the wave length of the GaAs diode (gallium arsenide) could be shifted from the infrared to the visible spectrum by merely changing the chemical composition of the crystal itself to GaAsP (gallium arsenide phosphide). Holonyak (1928 - ) developed the first practical visible-spectrum LED in 1962.

Holonyak received his B.S. (1950), M.S. (1951), and Ph.D. (1954) in Electrical Engineering from the University of Illinois. Before joining G.E. in 1957 he worked as a member of the technical staff at Bell Telephone Laboratories. He left G.E. in 1963 to begin a career as a professor of electrical engineering at the University of Illinois, Urbana, where he continues his teaching and research today.

Light-emitting diode technology was used for the digital display in the first digital quartz watch, the Pulsar.

The LED display used in the Hamilton Pulsar was developed with Monsanto. Early in his career at the University of Illinois, Nick Holonyak helped Monsanto set up their LED display division, a field which the company led for a number of years. The LED time display was commonly used in digital watches until 1977, when the LCD display became the preferred choice.