BIO – NANO - PHOTONICS
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.
The fundamental scientific and technological questions to be addressed are:
1. 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.
lactate
TeO42-
lactate
lactate
lactate
bacterium
TeO32-
TeO42e-
bacterium
TeO32-
lactate
lactate
lactate
Te(0)
e-
TeO42-
lactate
lactate
TeO42-
a
b
c
2. The precise control of physical and electronic structure in such nanoparticles enables the
development of fundamental structure-property relationships of complex
nanostructures. This, in turn, results in exceptional optical properties [1]:
 Absorption and emission properties are controlled by the nanostructure and
particularly tuneable across all the important photonic wavelength range in the
near infrared, i.e. from 0.7 – 1.8 micron.
 The nonlinear and photoemission properties are enhanced substantially compared
to similar chemically synthesised nanomaterials by increased density of states
due to complex constructive interplay of dielectric and quantum confinement.
 The excited state relaxation processes are generally in the ultrafast ps-fs range
due to structural confinement of the nanoscale – thus enabling applications in
ultra-high speed switching and controlling of light.

3. ‘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.
Technology
Devices
Coupling to SMF and
PLC*
Fabrication
Silica-based
Complex; Passive (e.g. arrayed
routers)
Well-Matched
Few Steps
Semiconductorbased
Compact; Active (e.g. optical
amplifiers,
lasers,
fast
modulators, and detectors)
Difficult due to tightly
confined
waveguide
modes
Complex
Epitaxial
Processing and Multiple Step
Photolithography
* SMF = Single mode fibres; PLC = planar light wave circuits
Hence, it is desirable to construct optical devices that share the favourable attributes of each
technology; i.e. mode matched to SMF, simple processing, and the capability of providing an
electro-optic effect, optical gain, and/or absorption. Bio-based nanoparticle doped polymer
waveguides will solve this problem.
4. 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.