Wednesday, 17 Jul 2019

UK researchers develop organic semiconductor lasers compatible with human eyes

The new laser approaches the fundamental limit in specific weight and thickness, with exceptional mechanical flexibility allows the device to be put on contact lens or a bank notes

University of St. Andrews - Organic laser on a £5 note

2 May 2018 | Editor

Researchers from The University of St Andrews have developed an ultra-thin membrane organic semiconductor based laser, opening up the possibility of ocular lasers - lasers on the the eye. The researchers sais these could be harnessed for new applications in security, biophotonics and photomedicine. The findings have been published in Nature Communications.

The research team led by Professors Malte Gather, Ifor Samuel and Graham Turnbull were also able to demonstrate ocular lasing using the cow eye as a model system. The researchers explained that the threshold of their membrane lasers is compatible with the requirements for safe operation in the human eye.

The new laser approaches the fundamental limit in specific weight and thickness, as well as an exceptional mechanical flexibility, which allows to put them on a contact lens or a bank notes.

The team also demonstrated that the devices were flexible and mechanically robust, even when attached to another object, and that their optical properties did not change over the course of several months.

They were then able to stick these ultra-thin lasers onto banknotes and contact lenses, where they suggest the devices could be used as flexible and wearable security tags. Flexible organic optoelectronics – in particular for displays, photovoltaics and wearable sensors – are on the verge of large-scale commercialisation, with prototype devices already achieving staggering form factors and bending curvatures.

The newly developed membrane laser now completes this family of ultra-thin and ultra-flexible organic optoelectronic devices.

University of St. Andrews -  Organic laser on a contact lens on a cow's eye

Figure: University of St. Andrews - Organic laser on a contact lens on a cow's eye

"In ancient Greece, Plato believed that visual perception is mediated by ‘eye beams’– beams actively sent out by the eyes to probe the environment."

"Plato’s emission theory has of course long been refuted, but superheroes with lasers in their eyes live on in popular culture and comic books. Our work represents a new milestone in laser development and, in particular, points the way to how lasers can be used in inherently soft and ductile environments, be it in wearable sensors or as an authentication feature on bank notes."

Professor Malte Gather, School of Physics and Astronomy at the University

"By floating a thin plastic film off a substrate we have made some of the world’s smallest and lightest lasers and put them on contact lenses and bank notes."

Professor Ifor Samuel, School of Physics and Astronomy at the University

"By varying the materials and adjusting the grating structures of the laser, the emission can be designed to show a specific series of sharp lines on a flat background – the ones and zeros of a digital barcode."

Markus Karl, worked on the new lasers as part of his PhD

Flexible and ultra-lightweight polymer membrane lasers

Markus Karl | James M. E. Glackin | Marcel Schubert | Nils M. Kronenberg | Graham A. Turnbull | Ifor D. W. Samuel | Malte C. Gather

Nature Communications | volume 9 | Article number: 1525 (2018)


Received: 06 December 2017 | Accepted: 19 March 2018 | Published: 01 May 2018

open access article


Organic semiconductors enable the fabrication of a range of lightweight and mechanically flexible optoelectronic devices. Most organic semiconductor lasers, however, have remained rigid until now, predominantly due to the need for a support substrate. Here, we use a simple fabrication process to make membrane-based, substrate-less and extremely thin (<500 nm) organic distributed feedback lasers that offer ultralow-weight (m/A<0.5 gm−2) and excellent mechanical flexibility. We show operation of the lasers as free-standing membranes and transfer them onto other substrates, e.g. a banknote, where the unique lasing spectrum is readily read out and used as security feature. The pump thresholds and emission intensity of our membrane lasers are well within the permissible exposures for ocular safety and we demonstrate integration on contact lenses as wearable security tags.


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