THE LATEST RESEARCH AND DEVELOPMENT NEWS IN MANUFACTURING AND TECHNOLOGYTECH FRONT New Lasers Could Power Communications, Computing t R


esearchers at the University of California San Diego have successfully demonstrated a laser based on an unconventional physics phenomenon called bound states in the continuum (BIC). The new BIC laser technology potentially could transform development of surface lasers by making them more compact and energy-effi cient for commu- nications and computing applications, and could also be de- veloped as high-power lasers for industrial and defense uses. “Lasers are ubiquitous in the present day world, from simple everyday laser pointers to complex laser interferome- ters used to detect gravitational waves. Our current research will impact many areas of laser applications,” said Ashok Kodigala, an electrical engineering doctoral student at UC San Diego and fi rst author of the study.


(spiral, donut or bell curve)—called vector beams—which could enable increasingly powerful computers and optical communication systems that can carry up to 10 times more information than existing ones. “Light sources are key components of optical data communications technology in cell phones, computers and astronomy, for example. In this work, we present a new kind of light source that is more effi cient than what’s available to- day in terms of power consumption and speed,” said Babak Bahari, an electrical engineering PhD student in Kanté’s lab and a co-author of the study. The research was published Jan. 12 in the journal


Nature. Bound states in the continuum are phenomena that have been predicted to exist since 1929, consisting of waves that remain perfectly confi ned, or bound, in an open system. Conventional waves in an open system escape, but BICs defy this norm—they stay localized and do not escape despite having open pathways to do so. In a previous study, Kanté and his team demonstrated, at microwave frequen- cies, that BICs could be used to effi ciently trap and store light to enable strong light- matter interaction. Now, they’re harnessing BICs to demonstrate new types of lasers. The BIC laser in this work is constructed


Schematic of the BIC laser: a high frequency laser beam (blue) powers the membrane to emit a laser beam at telecommunication frequency (red).


“Because they are unconventional, BIC lasers offer unique


and unprecedented properties that haven’t yet been real- ized with existing laser technologies,” said Boubacar Kanté, electrical engineering professor at the UC San Diego Jacobs School of Engineering, leader of the research team. BIC lasers can be tuned to emit beams of different wave- lengths, which is useful for medical lasers precisely target- ing cancer cells without damaging normal tissue. BIC lasers can also emit beams with specially engineered shapes


from a thin semiconductor membrane made of indium, gallium, arsenic and phosphorus, the scientists said, and the membrane is structured as an array of nano-sized cylinders suspended in air. The cylinders are intercon- nected by a network of supporting bridges, which provide mechanical stability to the device. By powering the mem- brane with a high frequency laser beam, researchers induced the BIC system to emit its own lower frequency laser beam (at telecommunication frequency). “Right now, this is a proof of concept demonstration that we can indeed achieve lasing action with BICs,” Kanté said. “And what’s remarkable is that we can get surface lasing to occur with arrays as small as 8 × 8 particles,” he said. In


March 2017 | AdvancedManufacturing.org 29


Image courtesy of Kanté group at UC San Diego.


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