Design, Fabrication, and Characterization of Silicon Mach–Zehnder Interferometers with Varying Path Lengths

Abstract:

The Mach–Zehnder interferometers (MZIs) on a silicon-on-insulator (SOI) platform were designed, fabricated, and experimentally characterized to evaluate their performance and extract waveguide parameters. Two unbalanced MZI devices with arm length differences of approximately 103 µm and 149 µm were implemented using 220 nm-high, 500 nm-wide strip waveguides. The devices were measured with a broadband optical source and an automated fiber–chip test setup to obtain their transmission spectra. Distinct interference fringes were observed, with free spectral ranges (FSRs) of about 5.37 nm and 3.72 nm for the two MZIs. From these spectral measurements, a waveguide group index of ∼4.19 was extracted for both devices, in excellent agreement with design simulations. The results confirm the accuracy of the design and demonstrate a straightforward method to calibrate waveguide index parameters using on-chip MZI structures. The presented MZIs achieved the expected performance, and this work provides a practical pathway for integrating and verifying interferometric components in silicon photonic circuits.

• Periodical: Materials Science Forum (Volume 1167)
• Pages: 81-88
• DOI: https://doi.org/10.4028/p-LyLvm2
• Online since: November 2025
• Authors: Sergey A. Nomoev*
• Keywords: Electron Beam Lithography, Integrated Photonics, Mach-Zehnder Modulator

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