Photonics

Photonics is a key driver for technological innovation and has become one of the most important sectors for future products and markets in the 21st century. It has tremendous leverage for creating products in a broad range of industrial sectors that multiply the value of initial photonic components and technologies many times over.

There is an emerging critical mass of photonics R&D in Ireland, much of which is centred at Tyndall.

The Institute includes some 12 internationally known principal investigators who work on many of the key aspects of photonics, ranging from the theory of quantum processes and materials at the atomic level, through optoelectronic and optical components and sub-systems, to advanced communications systems.

A critical challenge for R&D in photonics is the need to produce radical cost reduction for the end application. In the research focussed on communication systems, increasing reach and per-user bandwidth capacity in the access network is a priority. Furthermore, in both access and backbone networks, the goal is to reduce power demands, infrastructure and costs whilst enhancing service capability. Novel digital optical techniques have the potential to provide processing at very high speed.

A complementary research frontier in optical signal processing is in quantum optical technologies – quantum cryptography and quantum computing – and fundamental studies include work with micrometre-sized amplifiers. Important advances in light-emitting devices at Tyndall have included high-efficiency light emitting diodes, and low-cost lasers capable of high-speed wavelength switching. Significant advances have been made in the understanding of amplifiers and lasers based on quantum dots and, in the near future, this work will be enhanced by the introduction of new capabilities for advanced materials growth at Tyndall.

Looking forward, a strategic aim is to develop capabilities in photonic device packaging and integration, which are key to reducing manufacturing costs, whilst also increasing functionality and adding value.  

PiFAS (Photonic Integration From Atoms to Systems) is a Science Foundation Ireland funded Strategic Research Cluster tasked with the goal of developing and supporting photonics research in Ireland. It combines the activities of several research groups in universities (TCD, DCU, CIT, UCC) across Ireland to achieve an internationally-competitive critical mass of research effort.

The Cluster will develop advanced techniques for combining different photonic technologies in innovative ways. The PiFAS research team works closely with Irish researchers and industrial partners to develop the necessary expertise and infrastructure to achieve this goal.

For more information on PiFAS, please go to http://ww.tyndall.ie/pifas    

Microsphere light sources from UV to IR

Miniature multi-wavelength laser light sources are increasingly important in today’s world of integrated optical circuits, not only for telecommunications, but also for a growing number of mechanical and bio-sensing applications. To meet these demands, the Quantum Optics Group, led by Síle Nic Chormaic, are developing micron-sized spheres made from a novel heavy metal fluoride glass (ZBLALiP) containing erbium ions.

Light is confined to whispering gallery modes circling the equators of the microspheres where it can reach extreme intensities, causing frequency conversion of the 980nm input light to wavelengths ranging from UV to the near IR. Thirteen separate conversion processes in this material have now been identified, ?including 1.5? mm lasing, a performance unmatched by any other single glass material.

Low-cost phase modulation with quantum dots

Radio systems can modulate the intensity, frequency or phase of the emitted waves in order to convey information most efficiently. In optical communications however, only intensity modulation is widely used because of its lower cost, despite the transmission benefits of exploiting frequency or phase in the highest capacity systems.

Now, a low-cost route to phase modulation has been discovered by Guillaume Huyet’s team during their investigations of quantum dots – a new class of semiconductor. Lasers and modulators can be made from this material, so both can be fabricated on one chip, avoiding additional expensive packaging and alignment. Gigahertz modulation has already been demonstrated in early experiments.

Faster all-optical logic gates with the “turbo-switch”

A major goal of photonics is to bring into the optical domain the kinds of digital logic functions – such as regeneration and switching – traditionally performed by electronics. Devices based on semiconductor optical amplifiers (SOAs) can implement many of these functions optically, but their recovery rate is too slow to process signals faster than 40Gbit/s without impairment.

Now, a novel device, developed by Bob Manning and his team in the Photonic Systems Group and dubbed the “turbo-switch”, has been shown to increase the effective speed of an SOA and improve the quality of the output signal. ­An 85Gbit/s logic gate and a 170Gbit/s wavelength-converter have demonstrated that logic functions can be performed at speeds beyond the reach of electronics, while avoiding the cost of optical-to-electronic conversion.