Ultracompact topological photonic switch based on valley-vortex-enhanced high-efficiency phase shift.

Area of Science:

• Topological photonics
• Integrated photonics
• Nanophotonics

Background:

• Topologically protected edge states in valley photonic crystals (VPCs) are well-researched but integrated tunable devices remain underdeveloped.
• Existing topological devices lack efficient phase-shifting capabilities crucial for advanced functionalities.

Purpose of the Study:

• To investigate the phase-shifting theory of topological edge modes in VPC structures.
• To develop and demonstrate an ultracompact, tunable topological photonic switch for telecommunication wavelengths.

Main Methods:

• Theoretical analysis of phase-shifting in VPC-based topological edge modes.
• Experimental demonstration of enhanced π-phase tuning efficiency (1.57-fold improvement).
• Fabrication and testing of a 1x2 thermo-optic topological switch (TOTS).

Main Results:

• Demonstrated an ultracompact TOTS (25.66 × 28.3 μm) operating at 1530-1582 nm with low switching power (18.2 mW).
• Achieved the smallest reported 1x2/2x2 broadband optical switch size, including thermo-optic and electro-optic types.
• Confirmed robust high-speed data transmission using the proposed TOTS.

Conclusions:

• The study reveals the phase-shifting mechanism of valley edge modes, enabling efficient optical path manipulation.
• The developed TOTS represents a significant advancement in miniaturizing topological photonic devices.
• Findings pave the way for diverse topological functional devices in optical communications, nanophotonics, and quantum information processing.