Scalable Soft Photonics: Integrating Nanoscale Design Principles into Large-Area Devices

Modern photonic devices demand precise control over the size, shape, and spatial arrangement of nano-objects with nanometre accuracy across large, often flexible substrates—requirements that challenge conventional lithography and self-assembly methods.

In this talk, we introduce scalable strategies that exploit fluid instabilities and material interactions in thin films of optical glass, polymer, and liquid metal to achieve unprecedented control over nanoscale organization and optical response. First, we demonstrate a self-assembly approach for all-dielectric metasurfaces, enabling sub-10-nm feature control and producing sharp Fano resonances (Q ≈ 300) and high-purity structural colors over centimetre-scale areas. Second, by tuning thermal expansion mismatches between films and substrates, we realize large-area periodic nanostructures with dynamically tunable optical properties, including reversible mechanochromic and camouflage effects. Finally, we explore gallium-based liquid metal nanospheres embedded in soft polymers, which generate vibrant structural colors with stable, reversible reflectivity over 1,000 mechanical cycles.

Together, these results establish a unified framework for soft photonics, bridging nanoscale precision and macroscale functionality. The demonstrated approaches enable scalable, reconfigurable, and durable optical architectures, offering new opportunities for flexible displays, sensors, and adaptive photonic devices.

Subject Matter Level: Introductory - Assumes little previous knowledge of the topic

What You Will Learn:
• Metasurface basics
• Large area Micro/Nano fabrication

Who Should Attend:
• Undergraduate students with basic knowledge in optics.
• General audience with an interest in metasurface and large area fabrication

About the Presenter: Tapajyoti Das Gupta from IISc Bangalore

Tapajyoti Das Gupta obtained his BSc and Btech in Physics and Radio physics respectively, from the University of Calcutta in 2006 and 2009. He then moved to France, where he obtained his MSc in nanoscience from École Polytechnique (l’X) in 2012 and PhD in Condensed Matter Physics lab (PMC) from the same institute in 2015 under Prof. Thierry Gacoin and Alistair Rowe. He then joined Prof. Fabien Sorin’s lab of Fiber Optics and Photonics Devices (FIMAP) in École Polytechnique Fédérale de Lausanne (EPFL) from December 2015 to November 2019. He has been an assistant professor in the Department of Instrumentation and Applied Physics in Indian Institute of Science, Bangalore, since July 2020. His research interest includes finding solutions to fabricate large area metasurfaces and photonic devices for applications including displays, holography, instrumentation, and image processing.