An important research topic in engineering and science is the miniaturization of systems and components, where small size and weight, low power consumption and low manufacturing cost can offer new functionalities. In recent years the fields of optics and fluidics have merged to create the area of research known as "optofluidics". The unique properties of fluids (compression, flow, and variable refractive index) can be combined with optical devices to create systems with advantages in optical measuring, communication and imaging areas. Variable optical attenuators (VOAs) are components in optical communication networks for managing optical power levels. This thesis is focused on the design, fabrication and characterization of two novel optofluidics based single-mode fibre VOAs ("continuous fibre" type VOA and "fibre gap" type VOA). The first VOA is constructed from a side-polished optical fibre which is characterized by a sloping shape profile of the external cladding thickness. The fibre is positioned on top of a platform which exploits electrowetting-on-dielectric (EWOD) techniques to move a liquid droplet. By moving a liquid droplet across EWOD platform (and along the polished region of the fibre), optical attenuation can be obtained. The droplet, whose refractive index is equal to or higher than the refractive index of the fibre core, is accessing and leaking radiation from the optical evanescent field of the polished fibre which then modifies the optical attenuation. The level of attenuation depends on the position of the droplet; the attenuation increases as the cladding thickness reduces and the droplet moves closer to the fibre core. The second VOA is a fibre gap device, where a ferrofluid shutter/actuator is located in the gap between lensed single mode optical fibres. The ferrofluid shutter movement is controlled by a magnetic field and changes the light propagation between fibres. The level of attenuation is defined by the shutter position.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:658936 |
| Date | January 2015 |
| Creators | Dudus´, Anna |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24985 |
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