New Transistor Laser Could Lead To Faster Signal Processing
Researchers at the University of Illinois at Urbana-Champaign have demonstrated the laser operation of a heterojunction bipolar light-emitting transistor. The scientists describe the fabrication and operation of their transistor laser in the Nov. 15 issue of the journal Applied Physics Letters.
Source: Science Daily“By incorporating quantum wells into the active region of a light-emitting transistor, we have enhanced the electrical and optical properties, making possible stimulated emission and transistor laser operation,” said Nick Holonyak Jr., a John Bardeen Professor of Electrical and Computer Engineering and Physics at Illinois.
The same principle making possible the transistor – negative and positive charge annihilation in the active region (the source of one of the transistor’s three currents) – has been extended and employed to make a transistor laser, he said. Holonyak invented the first practical light-emitting diode and the first semiconductor laser to operate in the visible spectrum.
Unlike a light-emitting diode, which sends out broadband, incoherent light, the transistor laser emits a narrow, coherent beam. Modulated at transistor speeds, the laser beam could be sent through an optical fiber as a high-speed signal.
“This is a true, three-terminal laser, with an electrical input, electrical output and an optical output, not to mention a coherent optical output,” said Milton Feng, the Holonyak Professor of Electrical and Computer Engineering at Illinois. “It is a device that operates simultaneously as a laser and as a transistor.” Feng is credited with creating the world’s fastest bipolar transistor, a device that operates at a frequency of 509 gigahertz.
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