A Lateral MOS-Capacitor-Enabled ITO Mach-Zehnder Modulator for Beam Steering

• Published in: Journal of lightwave technology Vol. 38; no. 2; pp. 282 - 290
• Main Authors: Amin, Rubab, Maiti, Rishi, George, Jonathan K., Ma, Xiaoxuan, Ma, Zhizhen, Dalir, Hamed, Miscuglio, Mario, Sorger, Volker J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.01.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Beam steering; Electric fields; electro-optic modulator; Free-space optical communication; Indium tin oxide; indium tin oxide (ITO); Indium tin oxides; LiDAR; Lithium niobate; Mach-Zehnder interferometers; Mach—Zehnder; Optical device fabrication; Optical waveguides; Phase modulation; Phase shifters; Phased arrays; Photonics; Sidelobe reduction; Sidelobes; Silicon; Switches; Waveguides
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2019.2956719

Here, we experimentally demonstrate an Indium Tin Oxide (ITO) Mach-Zehnder interferometer heterogeneously integrated in silicon photonics. The phase shifter section is realized in a novel lateral MOS configuration, which, due to favorable electrostatic overlap, leads to efficient modulation (VπL = 63 V . μm). This is achieved by (i) selecting a strong index changing material (ITO) and (ii) improving the field-overlap as verified by the electrostatic field lines. Furthermore, we show that this platform serves as a building block in an end-fire silicon photonics optical phased array (OPA) with a half-wavelength pitch within the waveguides with anticipated performance, including narrow main beam lobe (<; 3°) and >10 dB suppression of the side lobes, while electrostatically steering the emission profile up to ±80°, and if further engineered, can lead not only towards nanosecond-fast beam steering capabilities in LiDAR systems but also in holographic display, free-space optical communications, and optical switches.