Scientific and Technical Objectives
Photonics technology has become an important part of our daily life, spanning telecommunications, displays, lighting, renewable energy to biomedical sensors and devices. Particularly, the current worldwide introduction of Fibre-to-the-Home technologies necessitates components which are efficient, cheap, easy to install and environmentally safe. Most active devices rely on inorganic semiconducting compounds. The increasing use of nanostructures has created a concomitant increase in complexity and cost of fabrication equipment. Furthermore, the chemicals used in most active devices, e.g. GaInAlAs or InP, contain heavy metals and toxic halides. In this proposal, a novel interdisciplinary approach to deal with all the above issues by microbiological fabrication of photonic nanocomposites is taken, which has the additional benefit of addressing lifecycle issues.
This proposal is a model project to demonstrate and develop the convergence of sciences, spanning the entire range from fundamental cutting-edge nanoscience to generic bio-based composite material development to ultrafast and nonlinear optics, leading ultimately to photonics applications.
- Microbiological synthesis and extraction of highly complex, but exceptionally well defined inorganic nanostructures consisting of compounds with fundamental scientific interest but also technological relevance, e.g. Se nanospheres and Te nanorods, As-S nanotubes, CdSe and ZnSe quantum dots. This bio-based methodology enables nanomaterials and complex structures which are too difficult or complicated to produce synthetically.
- The precise control of physical and electronic structure in such nanoparticles enables the development of fundamental structure-property relationships of complex nanostructures.
- ‘Green’ Polymer Photonic Nanocomposites - As such nanostructures can be incorporated into a similarly microbiologically fabricated transparent polymer host matrix, i.e. biodegradable Polyhydroxyalkanoate by either solution or melt processing, practical nanocomposites can be made relatively simply. This new class of ‘up-cycled, green’ materials represents a novel and promising approach to deal with the problems of raw material cost and continuity of supply, toxicity and recycling, with the additional benefit of addressing lifecycle issues and thus contributing to the preservation of our environment through reuse of heavy metal waste. In addition, these polymer nanocomposites will provide an ideal platform for new photonic technologies: Standard optical devices are based on guided-wave technology and use mainly traditional semiconductor and glass technology. However this has hit a limit given mainly by economic but also materials and fabrication restrictions.
- The fundamental study on the ultrafast and nonlinear optical properties of nanomaterials is a critical link to real-life applications. The backbone of photonic and information technologies is composed of photonic devices which modify optical signals by amplification, transmittance, modulation and transformation processes. A high performance photonic device requires a fast response time, strong nonlinearity, a broad wavelength range, low cost and ease of integration into an optical system. So far, a few materials, such as carbon nanotubes and Au and Ag nanoparticles have partially fulfilled the above requirements. Here we will explore the ultrafast nonlinear properties of microbiologically synthesised nanomaterials to demonstrate their usefulness in selected of nanophotonic devices, such as optical switches, saturable absorbers, mode-lockers, optical limiters and possibly also solar cells.