Silicon photonic sensors for induction welding joints in aerospace composite manufacturing

Abstract

The aerospace industry increasingly adopts thermoplastic composites for lightweight and sustainable aerostructures. Ensuring joint integrity demands advanced sensing for process control and Structural Health Monitoring (SHM). The EU-funded PLEIADES project develops an integrated photonic sensing solution for automated induction welding of composite joints, enabling precise real-time thermal control. We present the simulation, design, and evaluation results of bragg grating based silicon photonic PIC-based temperature and strain sensors with efficiencies of 72 pm/°C and 1 pm/με, at a 4 kHz monitoring rate, in a temperature and strain decoupling architecture. Furthermore, their small footprint (δ < 1.5 mm²), enabling high spatial resolution monitoring, crucial for detecting localized defects within the weld area without compromising joint quality or the structural integrity of the produced part.