Integrated Photonics for sensing applications
Context: Significant advances have been made in the field of silicon photonics, which now enable the development of sensors for medical, industrial and environmental applications. Compared to a purely optical approach, the interest in these integrated photonic systems lies in the advantages offered by both the high sensitivity of the measurement principle, small footprint and low cost, optimized performance (the manufacturing process is often CMOS compatible), and its inherent electromagnetic immunity.
The operation of these integrated photonic systems relies on the principle of propagation of light from a light source, such as a laser, within a waveguide which exhibits a high refractive index core surrounded by another material with a lower index (sheath) in a manner similar to an optical fiber. However, the propagating light is not entirely confined in the core but is also affected by variations in the refractive index of the sheath. This results in an effective refractive index which can vary as a function of the external perturbation applied on the sensing surface. Thus, by removing a part of this sheath in order to put the medium (which may be a gas, a liquid or a solid via the addition of a selective molecular coating) directly in contact with the guide, the index variations can be measured typically with increased sensitivity compared to others technologies.
In order to design very sensitive gas sensing devices, it is of utmost importance to develop a reliable library of all the fundamental photonic components/functions with good intrinsic performances (low loss, reproducibility …).
Objectives: This internship project aims to design and develop a library of fundamental integrated photonic devices such as broad band couplers, splitters, Bragg grating filters, Bragg couplers, Mach Zehnder interferometers, micro-ring resonators in Si3N4 and SOI process technology. In addition, modulators using the electro-optical properties of some specific polymer will also be addressed. During the internship, the components fabricated in the LAAS Cleanroom Facility (using e-beam, RIE, …) will be fully characterized using available equipment (e.g. optical spectrum analyzer, tunable lasers, etc). The obtained results will be compared with simulations and will be used to generate the device models that will be used to design more complex photonic circuits.
This project will benefit from both existing photonic circuits and the in-house SiN process developed during an ongoing PhD research.
Principal work will concentrate on analyzing, designing, fabricating and characterizing these integrated photonic circuits using the LAAS cleanroom facility and the associated characterization equipment.
Perspectives: Future work will investigate light injection into the photonic circuits via Bragg grating couplers and fiber arrays to reduce losses and optimize coupling.
Supervision: Dr O. Bernal, Dr H. C. Seat and C. Deleau,
Contact: Dr O. Bernal, LAAS-CNRS/ENSEEIHT-Toulouse INP (email: obernal@laas.fr)
Equipment: Optical spectrum analyzer, tunable laser, photonic characterization platform
Software: Klayout, ANSYS Lumerical FDTD, COMSOL, Matlab
Essential Qualification And Education Requisite :
- Currently enrolled in a Master program in Optics, Physics, Applied Physics, Optical Engineering, Photonics, or related fields
- Some experience in theoretical and experimental knowledge of photonics, Si and/or SiN
- Experience in Simulation tools (FDTD, EME …)
Preferred Requisite :
- Some experience in characterization of photonics devices in the laboratory
- Demonstrated potential for research
- Some experience in a cleanroom, including the use of state-of-the-art lithography, etching and thin film deposition tools and process Silicon or Silicon Nitride is a plus
- Team working in a strongly collaborative and multidisciplinary research environment.
We Offer
- 640 €/month allowance
- Diverse and dynamic work environment
- Duration: 6 months
- Expected start date between February 2022 – April 2022