1/17/2007 James E. Kloeppel, Physical Sciences Editor
The transistor laser, being developed by electrical and computer engineering professors Milton Feng and Nick Holoynak, Jr. made Eurekalert's "10 most accessed stories in 2006." EurekAlert! is the global science news service sponsored by the American Association for the Advancement of Science (AAAS).
Written by James E. Kloeppel, Physical Sciences Editor
The transistor laser, being developed by electrical and computer engineering professors Milton Feng and Nick Holonyak, Jr made Eurekalert's “10 most accessed stories in 2006.” EurekAlert! is the global science news service sponsored by the American Association for the Advancement of Science (AAAS).
The original story, “Transistor laser functions as non-linear electronic switch, processor,” written by James Kloeppel, physical sciences editor at the U of I News Bureau, was posted on EurekAlert on February 6, 2006. Since that time, it has been viewed 41,818 times, earning the #4 spot on the list of most accessed stories, which was also picked up widely by the news media around the world.
According to its inventors, the transistor laser has now been found to possess fundamental non-linear characteristics that are new to a transistor and permit its use as a dual-input, dual-output, high-frequency signal processor. By modifying the base region with quantum wells and resonator configurations, Holonyak, Feng, and their colleagues have shifted the transistor operation from spontaneous emission to stimulated emission. The altered recombination process of the transistor changes the device characteristics, giving near laser threshold a fundamental and potentially useful non-linearity.
"Transistors have never done this before," said Holonyak, a John Bardeen Chair Professor of Electrical and Computer Engineering and Physics at Illinois. "Operating as a new form of transistor, the transistor laser offers new signal mixing and switching capabilities."
The transistor laser combines the functionality of both a transistor and a laser by converting electrical input signals into two output signals, one electrical and one optical.
"Using separate base inputs, we can apply two independent signals to the active region of the transistor laser," said Feng, the Holonyak Chair Professor of Electrical and Computer Engineering at Illinois.
"We can mix them, manipulate them, so that we get out an electrical signal which is some multiple of the first input plus some multiple of the second input," Feng said. "We also get out an optical signal, which is modulated by some multiple of the first input plus some multiple of the second input."
The transistor laser also raises the possibility of replacing wiring between components at the chip- or board-level with optical interconnects, thus offering more flexibility and capability in electronic-photonic integrated circuits. Although its inventors say that it's too early to tell where all of this will go, there's obvious interest in the developing technology, as shown by the EurekAlert! results.
Since EurekAlert!'s debut in 1996, the website has continued to serve the global need for breaking science, medicine, and technology news. In 2006, EurekAlert! averaged over 20 million hits per month, a 35% increase over the previous year's average.
Illustration: Scanning electron microscope image of a dual-input heterojunction bipolar transistor laser (HBTL) on a Cu heat sink acting as frequency mixer for up and down conversion. The image shows a cleaved, front to back, segment of the laser crystal with emitter (E), base (B), and collector (C) metallization as shown. The laser output is shown schematically as hV and the electrical output as Vout. Both output signals produce integer multiples (mixing) of the input signals at frequencies mf1 +nf2. Credit: Milton Feng and Nick Holonyak