Guest lecture -- Kristinn B. Gylfason

Kristinn B. Gylfason, Professor at KTH Royal Institute of Technology gives the lecture Photonic MEMS in Silicon and 3D-printed Silica Glass for Programmable Photonic Circuits and Sensing

Abstract

Photonic integrated circuits (PICs) promise to be the optical equivalent of electronic integrated circuits (ICs). However, current PICs fall far short of electronic ICs in terms of the number of devices per chip. One roadblock is the power consumption and the footprint of active photonic components. By micromechanical actuation of PICs, we show orders of magnitude reduction of power consumption compared to current thermo-optic counterparts. We demonstrate our approach by implementing MEMS tunable photonic devices such as phase shifters, couplers, and wavelength filters. We realize our technology in a silicon photonics foundry platform and show complex circuits on a small chip. Furthermore, we show wafer-level vacuum-sealing of the silicon photonic MEMS circuits.

Optical spectroscopy is among the most important chemical analysis techniques due to its high specificity and long-term stability. For spectroscopic analysis of gas compositions, the mid-infrared (mid-IR) region is particularly important, owing to the rovibrational resonances in that spectral range. Hence, there is great interest in miniaturizing and reducing the power consumption of optical spectroscopic sensors, but until recently, the mid-IR range has been out of reach. We demonstrate a platform based on mid-IR silicon waveguides and show sensing of carbon dioxide and methane.

Silica glass is a high-performance material used in many applications, such as lenses, glassware, and fibers. However, modern additive manufacturing of micro-scale silica glass structures requires sintering 3D-printed silica-nanoparticle-loaded composites at ~1200 °C, which causes substantial structural shrinkage and limits the choice of substrate materials. We demonstrate 3D printing of solid silica glass with sub-micrometer resolution without a sintering step. This is achieved by locally crosslinking hydrogen silsesquioxane to silica glass using nonlinear absorption of sub-picosecond laser pulses. The as-printed glass is optically transparent but shows a high ratio of 4-membered silicon-oxygen rings and photoluminescence. Optional annealing at 900 °C makes the glass indistinguishable from fused silica. We demonstrate the utility of the approach by 3D printing an optical microtoroid resonator, a luminescence source, and a suspended plate on an optical fiber tip. This approach enables promising applications in photonics, medicine, and quantum optics.

Bio

Kristinn B. Gylfason has been a full Professor at the KTH division of Micro and Nanosystems since 2023. He received the title of Docent in Micro- and Nanosystems in 2015 and the Ph.D. degree in Electrical Engineering in 2010, both from KTH – Royal Institute of Technology, Sweden. He received the MSc and BSc degrees in Electrical Engineering from the University of Iceland in 2003 and 2001, respectively. His research involves photonic nanodevices for communications and sensing applications. Kristinn co-founded the start-ups Grein Research (https://greinresearch.com) and In2great Materials AB (https://in2great.se).