Semiconductor lasers on a graph

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

With decades of proven success, lasers have become central to many technologies used in manufacturing, communications, medicine and entertainment. Yet laser research continues, advancing current laser technology and developing new types of non-conventional light sources for new applications.

We have just pioneered nanophotonic lasers on a graph, formed by nanostructured polymer waveguide meshes, akin to nano-scale spider webs. These are efficient lasers, with a complex emission spectrum composed of many different colours emitting in many directions, that can be understood and tailored using network theory. They also have a unique sensitivity to the illumination profile, which we can use to control the lasing spectrum, and for example reach single colour emission.

We now want to push this research into III-V semiconductor laser platform, where lasers are more robust and can be designed with specific topologies. We will employ machine learning and mathematical graph theory to tailor the lasing characteristics, and achieve deterministic spectral, temporal and directional control of the lasing emission.

Our goal is to develop tuneable and multi-function lasers, which can be easily integrated into next-generation lab-on-chip devices, able to support the growth of future on-chip optical computation, information technology and diagnostic tools for healthcare. Being able to switch on and off their emission could enable data processing with >10 GHz speeds, and it could act as an optical transistor for analogue optical computing, as re-programmable processing units for neuromorphic computing, for data security, novel imaging and diagnostics technologies taking advantage of their very narrow spectral lines and high sensitivity.

Planned Impact

Lasers have played a central role in several technological developments for many decades, from communications to medicine, with an expected market value of $15 billion by 2022. This programme will bring forward a new type of nanostructured lasers, with direct impact in many technologies which use the laser as a light source, a signal-processing element, or a transducer.
The UK is a leader in photonics research and technology, and this programme will develop new disruptive lasing technologies which will help the UK photonics community maintain a leading edge in this emerging research area, specifically in optical information technology, biosensing, and lasing technologies.

Nanoscale optical processing and computation have the potential to replace electronic components due to their lower power consumption, increased speed and ease of long-distance signal propagation via optical fibres. Network lasing is easily integrated on chip, and can act as an analogue optical computing elements, able to switch, to act as an optical transistor, and to perform analogue operations with a speed of up to 100 GHz, limited by the gain dynamics. Network lasers could power future optical chips inside our computers or in data centres. Together with our partner in IBM we will exploit network lasers on chip for neuromorphic applications, where the laser is the computing element, and the software is loaded in the illumination pattern.

Network lasers may also be applied to biosensing and diagnostics technologies. Most conventional biosensors are based on fluorescence, while lasing is often neglected. We have recently shown for a simple random lasers, that lasing can replace conventional fluorescence sensors, and offer higher sensitivity. Within this research programme, the network laser with its multimode nature would increase the sensitivity of sensing-by-lasing even further, and have an impact on miniaturised screening for biomedical and healthcare diagnostics.


The project will promote light and light-based technologies and will raise public awareness of the value of photonics research, of lasing science and the optical properties of network materials. It will also provide high-quality training, mentorship and career development opportunities for the researchers involved in the project. This will promote interdisciplinary research, at the interface between nanophotonics, material science and network theory, and will inform policy makers of how fundamental physical science can advance practical technology.

Publications

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