Photothermal Switching of SOI Waveguide-Based Mach-Zehnder Interferometer with Integrated Plasmonic Nanoheater
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We theoretically and numerically investigated the photothermal switching of a Mach-Zehnder interferometer (MZI) based on two Si waveguides integrated with plasmonic nanoheaters. The nanoheater is a composite nanowire with Au/Al2O3/Au three-layer structure, which is designed to have a highly efficient optical absorption peak at wavelength of 1,064 nm. Based on this finding, we further analyze a MZI built with two 40-μm-long symmetric waveguide branches, each integrated with a 20-μm-long nanoheater. The optical switching power of the MZI device is 190 mW (280 mW) for the capped (buried) channel waveguide, when pumped by a circular Gaussian beam with a waist of 10 μm. Alternatively, the switching power can be reduced to 38 mW (56 mW) by using an astigmatic Gaussian beam, with a semi-major axis of 10 μm and an aspect ratio of 5. The switching response time of the MZI is 0.7 μs (1.0 μs) for capped (buried) channel waveguide design. Our design opens a new route for optically driven non-contact optical on-off switching with sub-microsecond time response.
KeywordsPhotothermal effects Metamaterial absorber Optical switching devices Mach-Zehnder interferometer Silicon-on-insulator strip waveguide
The authors thank Fei Lou (KTH Royal Institute of Technology) for the fruitful discussion. This work is supported by the Swedish Foundation for Strategic Research (SSF), the Swedish Research Council (VR), and VR’s Linnaeus center in Advanced Optics and Photonics (ADOPT). Min Qiu is also supported by the National Natural Science Foundation of China (Grant Nos. 61275030, 61205030, and 61235007).
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