The Evolution of LED Technology: From Discovery to Smart Lighting

The journey of LED technology began in 1907 when British inventor H.J. Round noticed electroluminescence in a silicon carbide crystal. Despite being a notable breakthrough, the inefficiency of silicon carbide in producing light led to limited progress. In 1939, Zoltán Bay and György Szigeti introduced a patent for a lighting device using silicon or boron carbide that emitted white, yellow-tinted, or green-tinted light, depending on the crystal’s impurities.

In 1957, Ruben Braunstein discovered a new potential use for LEDs in non-radio communication. Instead of radio waves, Braunstein demonstrated that LED light could carry sound over short distances, much like a photophone. This device worked by reflecting modulated light off a vibrating mirror caused by human speech, transmitting sound to a receiver which converted the light back into audio. While photophones traditionally relied on sunlight, Braunstein’s findings showed that LEDs could emit enough light to transmit sound.

The path to practical LEDs progressed further in 1961 when James R. Board and Gary Pitman discovered infrared light emissions. Although this emission was invisible to the human eye, it was significantly stronger than earlier discoveries. Then in 1962, Nick Holonyak Jr., working at General Electric, successfully developed the first visible-spectrum LED—laying the cornerstone for modern LED lighting.