Composite materials offer significant performance advantages due to their lightweight, high-strength, and high stiffness. This led to their adoption in several industrial sectors with particular emphasis on the aerospace industry which has undergone a transformation towards a composite-dominated new standard. In order to respond to the increased demand, it is mandatory to focus on an efficient and well-controlled curing cycle of the resin, which will lead to a significant reduction of cost and an increase in production speed. We investigate, a photonic solution, able of measure key monitoring values that facilitate optimization of the curing process. Simulation and evaluation results on a bragg grating based photonic integrated sensor, developed in 220 nm Silicon-on-Insulator platform, are presented. A multi-sensor deployment is considered, enabling monitoring of the temperature and the refractive index of the resin. Serially coupled bragg grating photonic elements will enable concurrent monitoring of both temperature and refractive index. Several bragg configurations have been investigated and experimentally evaluated, specifically regular and phase-shifted ones. Both TE and TM polarization operation sensors that have been designed and fabricated, will be presented. Their sensitivity on resin temperature and refractive index variation will be discussed, resulting in a comparative study outlining the benefits and disadvantages of each solution. Refractive index sensors are realized by employing post-processing etching techniques on Multi-Project-Wafer run fabricated silicon chips, on top of the periodic bragg grating element. The comparative study takes into consideration TE and TM polarization operation, regular and phase-shifted bragg grating configuration elements, while evaluating their sensitivity in temperature and refractive index variations. Temperatures considered are in the range of 27 °C to 200 °C, while refractive index values lay between 1.5 and 1.6. A Figure-of-Merit is proposed to facilitate the selection of multi-sensor deployment for specific temperature and refractive index ranges.

We demonstrate a sensing platform for composite manufacturing (RTM-6) process based on silicon photonics, being controlled by novel Process Monitoring Optimization Control (PMOC) system. The photonic multi-sensor is based on bragg grating components, allowing measurements of temperature, pressure and refractive index, and is packaged employing a ball lens fiber-to-chip interface. We present results of the packaged temperature photonic sensor regarding bandwidth, linearity and thermo-optic efficiency, being controlled by our PMOC system. We experimentally achieve 0.074 nm/C with R^2 = 0.995 linearity for temperature up to 180°C (RTM-6 compatible) with 1 kHz data acquisition and 0.2°C accuracy.