Researchers at the University of California, San Diego, have developed a laser based on an unconventional wave physics phenomenon known as bound states in the continuum — BIC. The new BIC lasers have the potential to be developed as high-power lasers for industrial and defense applications. The technology could also revolutionize the development of surface lasers for communications and computing applications. Schematic of the BIC laser: a high-frequency laser beam (blue) powers the membrane to emit a laser beam at telecommunication frequency (red). Courtesy of the Kanté group at UC San Diego. Bound states in the continuum are waves that stay confined in an open system. Conventionally, waves would escape from an open system, but BICs remain localized. Since they are unconventional, BIC lasers possess unique properties that have not yet been found in existing lasers. One key characteristic of the BIC laser is its capability to be readily tuned to emit different wavelengths of laser beams. “They are also capable of producing vector beams, which are essentially engineered shapes of the emission beam,” said Boubacar Kanté, an electrical engineering professor who led the research at the UC San Diego Jacobs School of Engineering. This is possible with BICs because “the lasing wavelength is tunable in the near-infrared range by controlling the dimension of the cylindrical nanoresonators.” These properties could be conducive in creating increasingly powerful computers and optical communication systems that can store even more information than current ones. The BIC system created by Kanté’s group is powered with a high-frequency laser beam that induced its own laser beam with a lower frequency. “Ideally, this BIC laser would be powered by a physical battery instead of being powered by another laser,” said Kanté. Kanté told Photonics Media that this would be the next step in the research of BIC lasers. The system built for the research, “is constructed out of epitaxially grown InGaAsP semiconductor material with quantum wells,” he said. “This material is unique in the sense that it comes with different energy levels or bands of energy — mainly two bands called conduction and valence bands.” Unique to the BIC laser is the capability of achieving surface lasing without compromising its compact form. “We demonstrate lasing in the telecommunication band [~1.55 μm] with laser arrays as small as 8 × 8 [~8 × 8 μm],” Kanté said. Other common surface lasers called VCELs (vertical-cavity surface-emitting lasers) need arrays about 100 times larger to achieve lasing. The smaller array consumes less power thus is more energy efficient than other surface lasers. The researcher speculated that one day VCSELs may be replaced by BICSELs (bound state in the continuum surface-emitting lasers), which could lead to smaller devices that consume less energy. The next step for this versatile technology is to create a BIC laser that is electrically powered. This would be a huge advancement toward achieving integration of BIC lasers into modern technology.