Department of Physics, Engineering Physics & Astronomy

Queen's University
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Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Gigahertz Modulation of a Silicon Photonic Crystal

Aaron Ali
MSc Candidate Supervisor: Prof. James Stotz, Queen's University

Thursday, November 22, 2012
10:30 AM @ Stirling 501


Photonic crystal (PtC) cavities are an increasingly important way to create all optical methods to control optical data. Not only must the data be controlled, but interfacing such devices with high frequency electrical signals is particularly interesting - especially if this occurs in the 1.55um telecom band. We present an experiment using Rayleigh surface acoustic waves (SAWs) to modulate the frequency of the guided mode of an L3-cavity PtC created on a Si substrate. This work has the potential to interface optical and electrical signals via a mechanical strain wave operating at gigahertz frequencies. A Si/SiO2 wafer can be etched to realize an undercut PhC, wave-guide and grating system on a chip. SAWs are coupled to the system by being generated in the farfield and travelling to the PtC. As Si is not piezoelectric, the fabrication of an operational SAW device requires the careful growth of a thin ZnO film on top of the Si structure. Aluminum interdigitated fingers biasing the ZnO layer allow an AC signal to transform into acoustic energy which is then used to modulate the PtC mode frequency. The ZnO can be removed from the PtC structure to recapture its originally designed performance.