Modelling of nonlinear effects in microstructured polymer optical fibres
Contacts:
Michael Frosz, DTU Fotonik, 4525-6369 (michael.frosz@fotonik.dtu.dk)
Ole Bang, DTU Fotonik, 4525-6373 (ole.bang@fotonik.dtu.dk)
http://www.mpof.fotonik.dtu.dk
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| The preform of a microstructured polymer optical fibre. The hole structure is clearly seen and is retained when the preform is drawn into a fibre less than 500 µm in diameter. |
Photonic crystal fibres (PCFs), also known as microstructured optical fibres, are a special type of optical fibre with air-holes running along the fibre length. The optical properties of the PCF can be controlled to a large degree through design of the structure, i.e. the size of the air-holes and the distance between them. In particular, one can make the core of the fibre smaller than a few microns. This means that the intensity of the light guided in the core obtains a very high intensity, which in turn leads to nonlinear interaction between the light and the fibre material. The nonlinear interaction can change the colour of the light propagating in the core. This is, e.g., used to transform single-coloured laser light into white light while still retaining the high intensity of a laser, also called supercontinuum generation.
The PCFs are traditionally made of silica glass, which is only weakly nonlinear. However, at DTU Fotonik we have the facilities to produce PCFs of polymer materials, which can be 100 times more nonlinear than silica. The polymer materials typically have much higher loss than silica, but are also more biocompatible, making them potentially useful for biosensors.
The project consists of simulating the propagation of laser pulses in an optical fibre. You will build your own software (e.g. in Matlab) to numerically solve the propagation equation. Then you will use this to design suitable air-hole structures which will give efficient nonlinear effects using a high power laser at a particular wavelength.