LED light source hmasa ber, semiconductor P-N junction-a light-emitting principle hmanga siam chu kum 1960 chho tir lam khan an lo siam chhuak a ni. Chutih laia thil hman chu GaAsP a ni a, red light (λp=650nm) a pe chhuak a ni. Driving current 20 mA a nih chuan luminous flux chu lumen pakhata hmun sang tlemte chauh a ni a, chu chuan luminous efficacy 0.1 lumen/watt vel a siam a ni.
Kum 1970 chho lai vel khan In leh N element te hman a nih avangin LED te chuan green (λp=555nm), yellow (λp=590nm), leh orange (λp=610nm) light an siam chhuak thei a, luminous efficacy chu 1 lumen/watt-ah tihchangtlun a ni.
Kum 1980 chho tir lam khan GaAlAs LED light sources a lo chhuak a, hei hian red LED te chu luminous efficacy 10 lumens/watt a nei thei ta a ni.
Kum 1990 chho tir lam khan thil thar pahnih-GaAlInP (mit sen leh yellow light pe chhuak) leh GaInN (green leh blue light pe chhuak)- hlawhtling taka siam chhuah chuan LED-te luminous efficacy nasa takin a tichangtlung a ni. Kum 2000 khan a hmasa zawk hian red leh orange region-ah watt khatah lumen 100 luminous efficacy nei LED (λp=615nm) a siam a, a hnuhnung zawk hian green region (λp=530nm)-ah watt khatah luminous efficacy 50 lumens nei LED a siam chhuak bawk.
