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arXiv · 2510.25530

Design of Carrier-Depletion-based Modulators on Commercially Available SOI Substrates of Varying Device-Layer Thickness

Anjali A R·Syamsundar De·Pranabendu Ganguly
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Abstract

We compare modulator designs on thick-film and thin-film silicon-on-insulator (SOI) substrates based on the carrier-depletion effect. This effect exhibits a lower junction capacitance as compared to its injection counterparts, leading to a higher electro-optic bandwidth, although the effective refractive index change is low. In this work, commercially available standard SOI substrates with device layer thicknesses of 5 {\mu}m, 3 {\mu}m, and 0.22 {\mu}m are chosen for designing carrier-depletion-based phase shifters, which are then utilized for the design of Mach-Zehnder modulators (MZMs). These MZMs are tested for various on-off-keying (OOK) modulation bit rates employing non-return-to-zero (NRZ) pseudo-random binary signal (PRBS). For the comparison of given designs, we find that the thick-film MZMs, which can provide higher fabrication tolerance and high power handling capabilities, support maximum modulation speeds in the order of a few Gbps, whereas it can go up to 20 Gbps for thin-film MZMs.

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Anjali A R, Syamsundar De, Pranabendu Ganguly. 2025-10-29. Design of Carrier-Depletion-based Modulators on Commercially Available SOI Substrates of Varying Device-Layer Thickness. https://arxiv.org/abs/2510.25530

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