【GIR Open Seminar】 Dr. Robert E. Simpson / University of Birmingham (U.K.)

Date	2026.3.9 (11：00 - 12：00)
Venue	Lecture Room L1111, 1st Fl. Building 11, Koganei Campus, TUAT
Speaker	Dr. Robert E. Simpson
Affiliation	University of Birmingham (U.K.)
Title	"Phase change material programmed photonics: plasmonic, dielectric, and interband resonances" ＜Abstract＞ Programmable metasurfaces require meta-atoms that can be tuned continuously across a full π-radian phase delay. Such reconfigurable optical elements can enable 3D displays, beam steering, and dynamic optical trapping. Many sulfide, selenide, and telluride compounds exhibit multiple stable structural states at room temperature. Transitions between these states induce radical changes to the electronic band structure, producing enormous refractive index contrast. For example, the refractive index of Ge₂Sb₂Te₅ (GST) increases from ~4 to ~6 in the mid infrared spectrum upon crystallisation, and this transition can occur on sub nanosecond timescales. These features make phase change chalcogenides compelling candidates for tunable and programmable photonic devices. We have identified and optimized a broad family of phase change materials (PCMs) suitable for active metasurfaces. Tuneable metasurfaces based on PCMs typically either exploit changes to the real component of refractive index to tune the resonant frequency of meta-atoms, or they exploit the imaginary component to change the absorption of the light in the meta-atom. However, many chalcogenide PCMs also exhibit interband “plasmonic-like” resonances in the visible spectrum. In this talk, I will summarise our progress designing and exploiting both dielectric and interband resonances in different chalcogenide materials to program metasurfaces. In so doing, I will discuss the intrinsic electronic and structural properties that lead to these tunable metasurface devices.
Language	English
Intended for	Everyone is welcome to join
Organized by	Institute of Global Innovation Research ”ENERGY” Kubo Team
Contact	Institute of Global Innovation Research, Institute of Engineering Prof. Wakana Kubo e-mail: w-kubo ( at ) cc.tuat.ac.jp
Remarks	This seminar will only be held face-to-face. Biography Robert E. Simpson is an Associate Professor in the School of Engineering at the University of Birmingham in the UK. Before Birmingham Robert spent almost 11 years at the Singapore University of Technology and Design (SUTD), where he formed the Advanced Chalcogenides Technologies & Applications Lab. Robert also spent his postdoc years as a Marie Curie and JSPS fellows in the Institute of Photonic Science (ICFO) in Spain and the Japanese Advanced Industrial Science and Technology (AIST) institute in Japan, where he developed phase change material tuned photonics devices and interfacial phase change memory, respectively. These days Robert’s research is focused on developing materials for sensing, energy-efficient computing, and programmable photonics.

Event

【GIR Open Seminar】 Dr. Robert E. Simpson / University of Birmingham (U.K.)