Electrically tunable topological notch filter for THz integrated photonics

• Main Authors: Gupta, Manoj, Kumar, Abhishek, Singh, Ranjan
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2023
• Subjects: On-Chip Cavity; Terahertz Notch Filter
• Online Access: https://hdl.handle.net/10356/170387
• Institution: Nanyang Technological University

Electromagnetic filtering is essential for emerging integrated photonic technologies and widely adaptable processing of high-bandwidth signals. The conventional electro-optic modulator-based photonic approach for signal filtering at microwave frequencies cannot be implemented at terahertz (THz) frequencies due to the unavailability of the THz signal-driven optical modulator. Here, an electrically tunable on-chip THz photonic notch filter based on the topologically protected valley hall waveguide-cavity platform is demonstrated. The device shows a significantly large notch suppression depth of more than 20 dB with a return loss of 13 dB in the entire tuning range of notch frequency. The feedback control circuit enables precise control of the notch frequency shift with a minimum step size of 7 MHz. This work extends the application of topological photonic crystals in developing THz-integrated photonic devices for transformative technologies, including sixth-generation (6G) communication and high-resolution spectral sensing.