University of Twente researchers have found an extremely efficient way to generate white laser light inside a chip. The findings, published in the journal Advanced Photonics Research, could benefit applications such as portable medical imaging devices, chemical sensing and lidar.
Common sense dictates that lasers can’t produce white light; they emit light in a very narrow wavelength range. And yet, through the exploitation of nonlinear optical processes, it’s possible to convert pulsed laser light into a broader wavelength range and even highly coherent white light. These so-called supercontinuum lasers, however, require very bulky and high-power laser sources, limiting their commercial application.
Working with integrated-photonics technology, the team at the University of Twente managed to significantly reduce the pulse energy needed by employing sign-alternating-dispersion waveguides: waveguides that are designed to control the dispersion of light by alternately widening and narrowing the beam of light. “With this method, we reduced the amount of pulse energy needed around a thousandfold compared to traditional methods,” says Haider Zia, the first author of the paper.