sentences:  These accomplishments parallel, but lag, the microelectronics revolution that started with the transistor, first demonstrated in 1947 (leading to the displacement of vacuum tube electronics in the marketplace).Although the laser had already been invented by Charles Hard Townes and Arthur Leonard Schawlow, separately by Gordon Gould, and separately in the Soviet Union by Aleksandr Prokhorov, there was no practical laser "chip" which would make the laser a commodity, one that today is displacing more inefficient lasers (those based on gas discharge or flashlamp designs) in the consumer, industrial, medical, and government marketplaces.Shortly after the accomplishments attributed to Townes and Schawlow, the possibility of lasing in a semiconductor device was recognized.