Thermo-optic epsilon-near-zero effects

Jiaye Wu; Marco Clementi; Chenxingyu Huang; Feng Ye; Hongyan Fu; Lei Lu; Shengdong Zhang; Qian Li; Camille-Sophie Brès

doi:10.1038/s41467-024-45054-z

Thermo-optic epsilon-near-zero effects

Nat Commun. 2024 Jan 26;15(1):794. doi: 10.1038/s41467-024-45054-z.

Authors

Jiaye Wu¹, Marco Clementi², Chenxingyu Huang^{3

4}, Feng Ye³, Hongyan Fu⁴, Lei Lu³, Shengdong Zhang³, Qian Li⁵, Camille-Sophie Brès⁶

Affiliations

¹ École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland. jiaye.wu@epfl.ch.
² École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland.
³ School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China.
⁴ Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
⁵ School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China. liqian@pkusz.edu.cn.
⁶ École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland. camille.bres@epfl.ch.

Abstract

Nonlinear epsilon-near-zero (ENZ) nanodevices featuring vanishing permittivity and CMOS-compatibility are attractive solutions for large-scale-integrated systems-on-chips. Such confined systems with unavoidable heat generation impose critical challenges for semiconductor-based ENZ performances. While their optical properties are temperature-sensitive, there is no systematic analysis on such crucial dependence. Here, we experimentally report the linear and nonlinear thermo-optic ENZ effects in indium tin oxide. We characterize its temperature-dependent optical properties with ENZ frequencies covering the telecommunication O-band, C-band, and 2-μm-band. Depending on the ENZ frequency, it exhibits an unprecedented 70-93-THz-broadband 660-955% enhancement over the conventional thermo-optic effect. The ENZ-induced fast-varying large group velocity dispersion up to 0.03-0.18 fs²nm^-1 and its temperature dependence are also observed for the first time. Remarkably, the thermo-optic nonlinearity demonstrates a 1113-2866% enhancement, on par with its reported ENZ-enhanced Kerr nonlinearity. Our work provides references for packaged ENZ-enabled photonic integrated circuit designs, as well as a new platform for nonlinear photonic applications and emulations.