Low-voltage high-speed Si Mach-Zehnder optical modulator with multi-cascade p/n junctions along waveguides

Ryuichi Furutani; Yoshiteru Amemiya; Masataka Fukuyama; Shin Yokoyama

doi:10.1117/12.922426

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10 May 2012 Low-voltage high-speed Si Mach-Zehnder optical modulator with multi-cascade p/n junctions along waveguides

Ryuichi Furutani, Yoshiteru Amemiya, Masataka Fukuyama, Shin Yokoyama

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Proceedings Volume 8431, Silicon Photonics and Photonic Integrated Circuits III; 84310W (2012) https://doi.org/10.1117/12.922426
Event: SPIE Photonics Europe, 2012, Brussels, Belgium

Abstract

We propose a Si Mach-Zehnder interferometer (MZI) optical modulator with multi-cascade p/n junctions along waveguides. So far a single p/n junction is set horizontally across the waveguide or vertically in the thickness direction. Compared with these types of MZIs, the newly proposed structure operates at low voltage because the depletion region expands from the p/n junctions at the both edges of the p or n type neutral region along the waveguide and the reverse bias voltage required to deplete the whole region becomes low. Furthermore, the doping concentration of the p and n regions can be reduced because there is no constraint on the width of the depletion region, while in the case of the horizontal or vertical junction type, the doping concentration must be high so that the depletion-region width is within the width or the height of the waveguide. The low doping concentration results in the low junction capacitance and leads to the higher operation speed. In this paper the detailed characteristics of the newly proposed MZI modulator have been simulated. The operation voltage of the proposed device is only 1.5V at 13dB (95%) modulation for the arm length of 5mm, while in the case of vertical junction, the operation voltage is 8V at the same modulation and for the same arm length.

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Ryuichi Furutani, Yoshiteru Amemiya, Masataka Fukuyama, and Shin Yokoyama "Low-voltage high-speed Si Mach-Zehnder optical modulator with multi-cascade p/n junctions along waveguides", Proc. SPIE 8431, Silicon Photonics and Photonic Integrated Circuits III, 84310W (10 May 2012); https://doi.org/10.1117/12.922426

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