UT Researchers Develop Ultraefficient White Light Laser On A Chip

A team of researchers from the University of Twente has made a breakthrough in ultraefficient on-chip supercontinuum generation. The findings, published in the journal Advanced Photonics Research, represent a major step forward in the field of integrated photonics and enable applications in portable medical imaging devices, chemical sensing and LiDAR.

Lasers normally emit light that is coherent: the waves they emit are identical in frequency and waveform. The coherent light makes it possible to send a narrow beam over extreme distances with very low noise. But this also means that lasers only emit a single colour of light. This limits their applications. In contrast, supercontinuum lasers are able to produce a continuous spectrum of colour and can therefore appear white. They are used in 3D imaging devices. However, it turns out that to generate this wide bandwidth of colours, supercontinuum lasers have a high peak power consumption (pulse energy), are enormous and have to be stabilized in a laboratory. This makes them expensive and less useful than initially expected.

Alternating Waveguides
The researchers from the University of Twente managed to significantly reduce this pulse energy needed. To do this, the team used so-called sign-alternating-dispersion waveguides. The waveguides 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 first-author Haider Zia, "This is an exciting development in the field of integrated photonics. Our method offers a more efficient way to generate supercontinuum light on a chip, which has many potential applications in medical imaging and LiDAR."s