# Topological Photonic Crystal Ring Resonator Pressure Sensor in the Optical Communication Range

## TL;DR

A new ultra-compact pressure sensor using topological photonic crystals achieves high sensitivity and unidirectional transmission in the optical communication range.

## Contribution

A novel pressure sensor design using valley photonic crystal topological ring resonators enables high-sensitivity sensing in the optical communication range.

## Key findings

- The sensor's resonance peak shifts from 1580 nm to 1489 nm as pressure increases from 0–10 GPa.
- The sensor achieves a maximum detection sensitivity of 24.34 nm/GPa with transmittance above 0.85.
- The compact sensor (7.5 μm × 6.5 μm) can be fabricated using existing nanotechnology.

## Abstract

What is the main finding?
An ultra-compact pressure sensor based on a valley photonic crystal topological ring resonator can achieve unidirectional transmission and high-sensitivity pressure sensing within the optical communication range.

An ultra-compact pressure sensor based on a valley photonic crystal topological ring resonator can achieve unidirectional transmission and high-sensitivity pressure sensing within the optical communication range.

What is the implication of the main finding?
The design principle of combining material deformation and refractive index changes with topological photonic crystals can be broadly applied to design ultra-compact high-performance pressure or strain sensors.

The design principle of combining material deformation and refractive index changes with topological photonic crystals can be broadly applied to design ultra-compact high-performance pressure or strain sensors.

Optical pressure sensors offer the advantages of high sensitivity, immunity to interference, and suitability for use in extreme environments. Based on the defect-immune, unidirectional transmission characteristics of valley photonic crystals (VPCs) and the refractive-index modulation of germanium under different pressures, we designed a topological ring resonator pressure sensor based on germanium VPCs. The shift of the resonance peak in the optical communication wavelength range with respect to pressure magnitude is studied to realize a pressure-sensing function. The results show that within the range of 0–10 GPa, the wavelength of the single resonance peak of the topological ring resonator pressure sensor shifts from 1580 nm to 1489 nm as the pressure increases. The sensor’s maximum detection sensitivity is 24.34 nm/GPa, and the transmittance across the bandwidth remains consistently above 0.85, with a maximum of 0.97. The germanium-based topological ring resonator pressure sensor features a compact structure with a size of 7.5 μm × 6.5 μm. It can be manufactured using existing nanofabrication technology and will have broad application prospects in the field of integrated photonic chips.