LEDs were fabricated using the principle of semiconductor P N junction light source. In the early 1960s, red light-emitting diodes first appeared in 1964, followed by yellow LEDs. It was not until 1994 that blue and green LEDs were successfully developed. In 1996, a white LED was successfully developed by Nichia Corporation (Japan). LEDs are widely used in indicators, signal lights, displays, landscape lighting, etc., because of their inherent characteristics, such as power saving, long life, vibration resistance, fast response, and cold light source. They are everywhere in our daily life. , household appliances, telephones, dashboard lighting, automotive anti-fog lights, traffic lights, etc., but due to the limitations of brightness, expensive and other conditions, can not be used as a universal light source.