University of Twente Student Theses


Integrated optical networks of microring resonators : a comparison between theory and experiment

Volbeda, H.K. (2016) Integrated optical networks of microring resonators : a comparison between theory and experiment.

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Abstract:For every application, specialized filters need to be designed to fit the needs and purpose of the application. In the designing process there is an almost endless list of posibilities, but in practice the design of the chip is limited to the scale and complexity of the geometry for the manufacturer. Within the manufacturing process there are a certain set of aspects that can have an dimensional error in them. The height of an waveguide can be grown in near atom-like precision. An error of one nanometer in the height will not alter the way the optical filter behaves, but the geometry of a waveguide in the planar direction is much more susceptable to error. In the thickness of the waveguide the error of fabrication can be about 10 nm, or around 10 atomic layers in the deposition process of fabrication. In the width is around 50 nm, which is almost comparable with the width of the waveguide. That is why the error in width is of more significance for it affects the performances of the waveguide negatively making it absolutely nescessary to understand if the filter on the chip one designed has the same dimensions as the end product recieved. The error of fabrication in the cross-section can give complications for the geometry of the waveguide structure: the optical filter. By analysing geometry and transmission spectra of an optical filter, fabrication errors can be revealed. By combining the mathematical theory of System Transfer Functions in the Z-domain, incorporating all variables of the filter into one formula relating input to output and with a fitting procedure one can extract the characterising coefficients needed to compare the designed with the received filter. In the following report, the description of two different optical filters will be presented, to show the use of digital filter theory on optical filters. Starting with a theoretical chapter explaining the working of a specific optical filter, an optical waveguide ring resonator and its performance. In the next chapter the Z-Transform and the system transfer function will be explained followed by a two chapters on visualising the system transfer function, rewriting it into a fitting model and the workings of the fitting procedure. The chapters following will discuss the setup of measuring and the results of those measurements. The last chapter will conclude the experiments explained in previous chapters.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics BSc (56962)
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