Minimizing Optical Loss While Enabling Efficient Phase Modulation in TMD-Based Devices (Nanyang Technological Univ., et al.)

A new technical paper titled “Hybrid tungsten oxyselenide/graphene electrodes for near-lossless 2D semiconductor phase modulators” was published by researchers at Nanyang Technological University, CNRS-International-NTU-Thales Research Alliance (CINTRA), University of Chicago, University of Wisconsin-Madison, Chungnam National University, National Institute for Materials Science, MIT, and Singapore University of Technology and Design.

Abstract

“Optical phase modulators are critical components in integrated photonics, but conventional designs suffer from a trade-off between modulation efficiency and optical loss. Two-dimensional materials like graphene offer strong electro-optic effects, yet their high optical absorption at telecom wavelengths leads to significant insertion losses. Although monolayer transition metal dichalcogenides (TMDs) provide exceptional telecom-band transparency for low-loss electro-refractive response, their practical implementation in phase modulators requires top electrodes to enable vertical electric field tuning, which typically introduces parasitic absorption. Here, we address this challenge by developing hybrid tungsten oxyselenide/graphene (TOS/Gr) electrodes that minimize optical loss while enabling efficient phase modulation in TMD-based devices. The UV-ozone-converted TOS (from WSe₂) acts as a heavy p-type dopant for graphene, making the graphene transparent in the NIR region while enhancing its conductivity. Our complete device integrates a hybrid TOS/graphene transparent electrode with a hexagonal boron nitride dielectric spacer and monolayer WS₂ electro-optic material on a SiN microring platform. This achieves a high modulation efficiency of 0.202 V·cm while maintaining an exceptionally low extinction ratio change of just 0.08 dB, demonstrating superior performance compared to modulators employing conventional electrodes. Our breakthrough in near-lossless phase modulation opens new possibilities for energy-efficient optical communications, photonic computing, and fault-tolerant quantum networks.”

Find the technical paper here.  Published Jan 2026.

Guo, Shi, Sung-Gyu Lee, Xiangxin Gong, Lalit Singh, Rui Yu, Ahmad Sholehin Bin Juperi, Seoungbum Lim et al. “Hybrid tungsten oxyselenide/graphene electrodes for near-lossless 2D semiconductor phase modulators.” Light: Science & Applications 15, no. 1 (2026): 42. Creative Commons license.