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Fabrication of a planar optical waveguide cleaved with micrometer precision

Kamerbeek, A.M. (2008) Fabrication of a planar optical waveguide cleaved with micrometer precision. Bachelor's Thesis, Physics.

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Abstract

For the research involved with the realization of a optical memory element it is necessary to fabricate waveguides. The wafer used to create these waveguides has a heterostructure top layer which forms the waveguide. Etching the top layer of the wafer allows for determining the dimensions of the waveguide. The challenge is to fabricate a waveguide which is as close as 1 μm from the wafer edge. To meet this challenge a method is developed for cleaving off excess substrate material with a precision in the order of micrometers. After introducing a double scribe in the GaAs wafer it is possible to predict the wafer cleaving location with a precision of a micrometer. The edge of the cleaved wafer shows sub micrometer roughness and therefore allows the placing of a waveguide entrance as close a 1 μm from the wafer edge. There is however a small chance the sample will not be break smooth enough at the predicted location. This could result in destroying the final device since cleaving is the last step in the fabrication process. Etching channels in a wafer, mimicking a scribe, does not result in pinning down the location the wafer breaks when cleaved. An attempt was made to fabricate waveguides using gold as an etching mask. This failed, most likely because the adhesion metal, titanium, between the GaAs sample and the gold is dissolved in the etching mixture of H2SO4:H2O2:H2O. Some basic equations for a symmetric planar waveguide where derived giving insight in the basic workings of the device. The coupling efficiency of the waveguide input was calculated to be 0.3702 taking into account Fresnel reflection at the end face of the waveguide at normal incidence. The waveguide is shown to be single mode and has a NA of 0.58.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Physics
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 07:45
Last Modified: 15 Feb 2018 07:45
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/9454

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