DHA - Simulations
The objective of our project is to investigate the science behind holographic optical tweezing and
to discover its potential as a method of assembling useful microstructures. The main benefit of
the machine we have in Bristol is that it can manipulate many particles concurrently and dynamically
as the trapping positions of the focussed beams can be controlled in real time using a computer.
We have developed some finite-difference, time-domain code to calculate the forces and torques
on particles trapped in the optical tweezer. The focus was on modelling optically and geometrically
anisotropic particles and the effect on trapping particles with multiple beams.
 Figure 1. Side view showing the relative intensity of three Gaussian beams trapping a 3 μm long silica rod with radius 45 nm. The dashed line indicates the source. The intensity variation is shown as false colours varying from red (most intense) to purple (least intense). The vertical scale is stretched compared with the horizontal scale. |
We have also been using the University's new supercomputer (Bluecrystal) to model the propagation of light through fully three dimensional photonic band gap crystals. These interesting materials may have many uses including quantum information, data transfer, low threshold lasing, negative refraction and all optical transistors.
 Figure 2. Side view showing the electric field strength of light entering a 3D face centred cubic crystal made from spheres of air surrounded by silicon. One column of the spheres in the centre is missing allowing light to propagate through. It can be seen that the light is restricted to this waveguide. |
DHA linksThe links below provide information on other areas of the DHA project.