Lab-Funded Research Shatters Traditional Notions of Laser Limits Published Feb. 25, 2010 By Maria Callier Office of Scientific Research ARLINGTON, Virginia -- University of California Berkeley Professor Xiang Zhang, a researcher funded jointly by Air Force Research Laboratory's Multidisciplinary University Research Initiative and the National Science Foundation, demonstrated the world's smallest semiconductor laser, a milestone of considerable importance in terms of Air Force communications, computing, and biohazard detection applications. The semiconductor, called a plasmon, can focus light the size of a single protein in a space smaller than half its wavelength, all while maintaining the laserlike qualities that prevent the microscopic beam's dissipation over time. Proposed nearly 7 years ago, plasmonic laser technology has heretofore defied demonstration. Dr. Zhang's breakthrough experiment therefore constitutes a key discovery based on its potential to eliminate optical loss and render plasmonic capabilities viable for a broad spectrum of critical applications. Dr. Zhang's research team met the challenge of devising a realistic plasmonic laser design by combining semiconductor nanowires (1,000 times thinner than a human hair) with a metal surface, separating these components by an insulating gap of only 5 nm (the size of a single protein molecule). Though these ultrasmall sizes and measurements contributed to an even greater challenge--showing how plasmonic lasers are able to bridge electronics, optics, and photonics on the nanometer scale--the team was ultimately able to demonstrate these properties by creating a confined space capable of holding and sustaining light during the course of the experiments. Forecasts for the next generation of plasmonic lasers, called nanolasers, include a built-in capacity for probing and manipulating molecules. These devices will be of substantial interest to the AF due to their advancement of ultrasensitive biodetection, nanoscale optics, and enhanced communication systems. They are also envisioned as benefiting such areas as health care, optics-based telecommunications, and optical computing. Meanwhile, Dr. Zhang eagerly awaits the next phase of his own research, when he and his colleagues will create a version of the plasmonic laser that requires no design modification but is nonetheless electrically operated and fully integrated with semiconductors.