Prof. Bill Gillin Project Abstracts
BSc Project Abstracts
Design of an automated interferometer
Interferometers rely on splitting a beam of light and sending it it two directions before recombining, a change in path difference between beams causes a change in the interference pattern. This can be used to detect very small changes in the length of objects, or to detect changes in refractive index. The purpose of this project is to design a computer interface for an optical detector and to characterise the stability of an interferometer and to determine the smallest length changes that can be measured. The second stage will be to design apparatus to allow for accurate measurements to be made in a range of systems.
Organic magnetoresistance
It has recently been discovered that the application of a magnetic field to an organic light emitting diode causes a change in both the efficiency of the device and the current passing through it. This project will involve fabricating a variety of organic light emitting diode devices and characterising their properties as a function of magnetic field.
Computer automation of the measurement of big G
Big G (The gravitational constant) is the most poorly defined physical constant we have with accepted value only being defined to about 0.01%. The Cavendish experiment to measure Big G relies on measuring the gravitational attraction of a pair of lead masses which is measured by the force they apply to a torsion balance using the deflection of a laser beam of a mirror attached to the balance. The purpose of this project is to design the electronics to detect the deflection of the laser beam and to interface this information into a PC so that the experimental data collection can be automated.
MSci and MSc Research/Investigative Project Abstracts
Energy transfer and population inversion in organic lanthanide materials
We have recently demonstrated the onset of population inversion in erbium ions in an organic host material. This observation opens the possibility of producing optical amplifiers and lasers that can be integrated directly onto silicon wafers. The approach we used was to have two organic molecules, one of which contains the erbium ions and the other of which is a chromophore. This is an organic molecules which strongly absorbs light and yet can transfer the energy from the absorbed photon directly into the erbium. Using this approach we have been able to increase the effective absorption cross-section for the erbium by a factor of 10000, which means that we can use very low optical pump powers to produce population inversion. This project will look at investigating the effect of changing the chromophore molecules on the energy transfer and excitation of the erbium.
Organic up-conversion phosphors
Up-conversion is the process where low energy photons (infrared) are converted to higher energy ones (visible). One process by which this can occur is by using a combination of lanthanide ions (such as ytterbium and terbium) where the ytterbium ions can absorb low energy photons and form an excited state with a long lifetime. Two of these ions can then transfer that energy to a higher energy state in the terbium ion which can emit a visible photon. In order for this process to occur it is necessary to have the lanthanide ions in an environment that provides then with a very high quantum efficiency in order to give them time to interact with each other. We have recently developed a range of new organic lanthanide containing materials which demonstrate very high (~100%) quantum efficiency and hence should be very suitable for up-conversion applications. This project will involve producing samples of these materials and characterising them for their optical properties.
