Second-harmonic generation in germanium-on-insulator from visible to telecom wavelengths

• Main Authors: Wang, Yadong, Burt, Daniel, Lu, Kunze, Nam, Donguk
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Electrical and electronic engineering; Germanium; Nonlinear Optics
• Online Access: https://hdl.handle.net/10356/161231
• Institution: Nanyang Technological University

The second-order $\chi^{2}$ process underpins many important nonlinear optical applications in the field of classical and quantum optics. Generally, the $\chi^{2}$ process manifests itself only in a non-centrosymmetric dielectric medium via an anharmonic electron oscillation when driven by an intense optical field. Due to inversion symmetry, group-IV semiconductors like silicon (Si) and germanium (Ge) are traditionally not considered as ideal candidates for second-order nonlinear optics applications. Here, we report the experimental observation of the second-harmonic generation (SHG) in a Ge-on-insulator (GOI) sample under femtosecond optical pumping. Specially, we report the first-time measurement of the SHG signal from a GOI sample in the telecom S-band by pumping at $\sim$$3000$ nm.