Research & Experience

Integrated, low-loss and efficient systems for data-intensive applications such as augmented and virtual reality demand on-chip photonic circuits — a key enabler for 6G wireless networks and intra- and inter-chip communication. Valley Photonic Crystals (VPCs) are a promising platform: they support topological interfaces along which light propagates with minimal loss and backscattering through unidirectional edge modes.

The ever-increasing demand for higher data rates pushes beyond the conventional 300 GHz band, whose ~120 GHz of bandwidth makes the path to Tbit/s difficult. The 600–700 GHz range, around the 650 GHz atmospheric window, offers far more bandwidth. In this thesis I designed, simulated, fabricated and experimentally demonstrated several THz passive functions — waveguides, bent waveguides, filters and resonators — for the 600 GHz range.

By varying interfacial designs and air-hole geometries, I introduced controlled variations in topological protection, showing that a partial break-up of topological protection can itself be an asset for designing on-chip passive functionalities. The work focuses on bearded and zigzag junctions with appropriate air-hole geometries for VPC unit cells, and verifies the scalability of topological protection through THz topological ring resonators and double-cavity resonators operating near 600 GHz — providing functional tuning of devices at chip level.

The thesis also proposes topological filters for the 600 GHz band. After design and fabrication on SOI, a filter was fully characterized and validated inside a 600 GHz communication system, experimentally handling up to 3 × 40 Gbit/s. Together, these demonstrations contribute towards smart, highly integrated THz photonic circuits built on silicon passive functions for 6G technologies and beyond.