The aim of this four-year Basic Technology Research Programme is to develop a new generation of micron sized tunable coherent light sources, i.e. continuously tunable, multi-wavelength lasers, based on ordered organic chiral structures. The size of these lasers would be less than the dimensions of the human hair, i.e. 10µm×10µm, and the spectral range will be from the near ultra-violet to the near infra-red. Such lasers do not yet exist although there are small single wavelength output semiconductor lasers being developed and produced using expensive Si-based solid state technology. Here the vision and technologies are different. All organic lasers will have many advantages ranging from low-cost, ease of production, infinite wavelength tunability (in the visible spectrum), as well as micron length scale size.

Fig.2: Red & green emission in photonic bandgap devices.

This Basic Technology Research Programme will produce a generic technology base that will be adaptable to a broad range of research problems and challenges spanning the multidisciplinary interests of the different research councils, (primarily EPSRC, BBSRC, and MRC). It will also lead to a UK manufacturing capability (e.g. in materials, optoelectronic devices, and spectroscopy).

Fig.1: A liquid crystal laser (red), being optically
pumped by a Nd:YAG laser (green).

Our lasers will be based on two essential thin film elements: 1) a light emitting organic moiety, excited optically or electrically, incorporated in 2) a tunable 1-, 2- or 3- dimensional Photonic Bandgap Organic Structure (PBOS). Thus the possibility exists of a multi-wavelength tunable source that may emit in 1-, 2- or 3-dimensions simultaneously with the PBOS providing a distributed feed-back (DFB) that allows the laser cavity (resonator) to be formed without mirrors. The PBOS structure selects the particular lasing mode with a well-defined wavelength, direction and the large far field coherence area. The key advantage of the PBOS systems is that they are based on Soft Organic Matter (eg: chiral liquid crystals or functionalised polymers, or indeed bio-polymers) in which the bandgap can be readily tuned by external agents, ie: electric and magnetic fields, UV light, temperature, mechanical stress, chemical species etc., thus changing the wavelength output and direction of the laser beam. It is this tunability coupled with the micron size and the potential ease of production that will open up new opportunities for applications in different areas of medicine (dermatology, introscopy, lab in a capsule, diabetes detection, etc), biology (cell recognition, DNA and disease analyses, etc), sensing (chemical, external field, virus, TB etc), optical micro-circuitry (all-optical micro-circuit board, etc.), telecommunications engineering (sources, optical switches, routers, interconnects etc.) and displays (micro-displays, large-area polariser-free displays, flexible devices, etc.).