Integrated optical modulators based on photonic crystals

Gövdeli, Alperen
Photonic Crystals, artificial optical structures making manipulation of the light possible, have become a popular platform since their first development. Here, such optical components are studied theoretically and their unusual behaviors are utilized for integrated optics components. In particular, ability to change the effective index contribution of photonic crystals is exploited for the design of a low-voltage and area efficient integrated optical modulator. Variety of different aspects are compared between the existing on-chip modulator implementations and a novel approach based on photonic crystals is presented for further improvement. The proposed design is a Mach-Zehnder interferometer whose arms contain identical photonic crystal slabs. In order to create a relative phase along the arms of the interferometer, plasma dispersion effect is utilized where the novelty of the design comes from the source of the phase shift. Unlike the existing optical modulators in the literature, plasma dispersion effect is used to perform a band-to-band transition on the photonic crystal at the operation wavelength. According to the numerical analyses performed on photonic band diagram of photonic crystals, such transition provides a huge effective index change leading to a large phase shift, which results in the possibility of extremely small device sizes and low operation voltages for a proper intensity modulation at the output at extremely high speeds.


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GÖVDELİ, ALPEREN; Kocaman, Serdar (2019-01-01)
A Mach-Zehnder Interferometer based optical modulator composed of photonic crystals as phase shifters is presented. The switching process relies on the phase modulation along the arms of interferometer resulted from the photonic band shift of the photonic crystal regions. A small bulk index change leads to a large effective index difference between two arms of the interferometer and a small foot-print device can operate as a modulator. Presented MZI-based optical modulator is shown to have tunable bandwidth...
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Citation Formats
A. Gövdeli, “Integrated optical modulators based on photonic crystals,” M.S. - Master of Science, Middle East Technical University, 2018.