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.
"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 transistors 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 worlds fastest bipolar transistor, a device that operates at a frequency of 509 gigahertz.
At laser threshold - where the light changes from spontaneous emission to stimulated emission - the transistor gain decreases sharply, but still supports three-port operation, Feng said. "The electrical signal goes down, but the optical signal goes up."
Earlier this year, Feng and Holonyak reported their discovery of a three-port, light-emitting transistor. Building upon that work, the researchers fabricated the transistor laser in the universitys Micro and Nanotechnology Laboratory. Unlike traditional transistors, which are built from silicon and germanium, the transistor laser is made from indium gallium phosphide, gallium arsenide and indium gallium arsenide, but can employ other materials in this family (the so-called III-V compounds). "This work is still very much in its infancy," Holonyak said. "There is much more to be learned, including how to separate and optimize the transistor laser output between electrical signals and light signals."
Down the road, ultra-fast transistor lasers could extend the modulation bandwidth of a semiconductor light source from 20 gigahertz to more than 100 gigahertz. Used as optoelectronic interconnects, transistor lasers could facilitate faster signal processing, higher speed devices and large-capacity seamless communications, as well as a new generation of higher performance electrical and optical integrated circuits.
Co-authors of the paper with Feng and Holonyak are postdoctoral research associate Gabriel Walter and graduate research assistant Richard Chan. The Defense Advanced Research Projects Agency funded the work.
James E. Kloeppel | UIUC - News Bureau
Neutrons pave the way to accelerated production of lithium-ion cells
20.03.2018 | Technische Universität München
Monocrystalline silicon thin film for cost-cutting solar cells with 10-times faster growth rate fabricated
16.03.2018 | Tokyo Institute of Technology
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
20.03.2018 | Physics and Astronomy
20.03.2018 | Physics and Astronomy
20.03.2018 | Earth Sciences