Laser diodes conquer the smartphone
VCSEL Day 2018 at Ulm University

Ulm University

They scan faces, recognise gestures and capture movement without any contact: vertical emission laser diodes can be found everywhere today. These so-called VCSELs - the commonly used abbreviation, pronounced "vixels" - are not only found in smartphones and computer mice, but also in highly automated vehicles and production lines. The 11th VCSEL Day 2018 will be dedicated to this special laser light technology, which is highly sensitive and at the same time gentle to materials. The European symposium will take place at Ulm University from 12 to 13 April.

"Researchers from Ulm University have a hand in this current boom of special laser diode technology. They did, after all, lay the foundation stone for the company 'Philips Photonics', one of the world's leading VCSEL producers today, with the successful spinoff 'Ulm Photonics' in 2000", explains host Professor Rainer Michalzik, group leader at the Institute of Optoelectronics. It was from this institute that the technology start-up sprouted. The VCSEL Day in Ulm will address current developments, technical challenges, new trends and new application opportunities with respect to the new technology. Roughly a hundred participants from all over Europe are expected to attend, including scientists and numerous experts and interested parties from companies.

From data transmission to sensory technology and imaging

Surface emitters, as vertical-cavity surface-emitting lasers are also known, have been used since the mid 90's, especially for data transmission via fibreglass cables.  The second VCSEL wave came after the turn of the millennium: with the use of VCSELs in optical computer mice, a new mass market was tapped. A third technological wave was triggered as the use of lasers in smartphones spread, but it was also due to new developments such as autonomous driving or automation of industrial processes. "New impulses for laser diode research can be expected in particular from the fields of sensor technology and imaging", Michalzik predicts.

30,000 infrared dots for face recognition

"Anyone with a new iPhone X is already holding a current example in their hands", according to the optoelectronics expert. The iPhone X performs user identification via FaceID, which employs a procedure for face recognition based on these modern laser diodes. 30,000 infrared dots are projected onto the face, all of which are invisible to the human eye. A camera captures the distortion of the dot pattern and, from that, complex algorithms determine the form of the face as a three-dimensional height profile. And because these technical high-performance systems have become so small and compact - thanks to nanomaterials and miniaturised construction - the whole thing still fits into your pocket.

Promising applications are also conceivable in the future. Scientists are already researching systems in which coloured VCSEL information can be projected directly into the eye as light stimulus. Virtual and real images will be merged directly on the retina.

A VCSEL for optical data transmission (red luminous dot) and a glass fibre positioned in front of it. With a diameter of an eighth of a millimetre, the fibre is only about 50% thicker than a human hair. (Photo: Institute of Optoelectronics/Uni Ulm)
Prof Rainer Michalzik presents new developments in VCSEL research. (Photo: Elvira Eberhardt/Uni Ulm)
University President Prof Michael Weber welcomes international conference guests. (Photo: Elvira Eberhardt/Uni Ulm)