Observation of Topological Flat-Band States in Photonic Lattices
We report the observation of topological flat-band states in photonic lattices fabricated using femtosecond laser writing. Topological photonic lattices are optical structures that remain insulating in the bulk while supporting robust, unidirectional edge states immune to backscattering. By embedding a flat-band within the topological bandgap, we introduce compact localized modes that can trap light, enhance light-matter interactions, enable diffraction-free transport and crucially interact with topological edge states. Using helical modulation of waveguides in a Lieb lattice, we realize a photonic Floquet topological insulator where both effects coexist. These results reveal a new interplay between topology and flat-band physics, with promising applications in quantum information processing, imaging, lasing, and optical computing.
Bhargava is currently a PhD student in Dr. Miguel Bandres’ Emergent Photonic Phenomena group. Bhargava received her Bachelor’s degree in Communication and Computer Engineering at the LNM Institute of Technology, a Master’s Degree in Photonic Networks Engineering from Aston University, and a Master’s Degree in Optics from the University of Rochester. Her research focuses on the design, simulation, fabrication, and characterization of photonic lattices, encompassing a range of structures from photonic lanterns to topological arrays.
Runners-Up
Broadband integrated photonic devices on thin film lithium niobate
The thin-film lithium niobate (TFLN) integrated photonic technology has matured tremendously in the past few years for high-performance electro-optic, nonlinear, and quantum-optic applications. Recent interest has grown in integrated wideband filters for on-chip photonic systems, such as optical combs and nonlinear circuits. With a wide transparency window ranging from the ultraviolet (UV) to the mid-infrared, ultra-wideband filters can be designed to exploit the full range of properties of lithium niobate. Versatile dichroic short-, long-, and band-pass filters with ultrawideband operation over two octaves of bandwidth as well as 700-nm reconfigurable cutoff range are designed, and the feasibility of such multi-octave spanning filters is demonstrated. Furthermore, design of the wideband linear optical isolator on TFLN using these filters is analyzed.
Kulkarni is a PhD student in Dr. Sasan Fathpour’s Integrated Photonic Emerging Solutions group.
Ultracompact, on-axis LCoS Illumination system with local dimming for waveguide-based AR displays
Augmented reality (AR) displays, as a rapidly advancing technology, are evolving toward lighter and more comfortable near-eye systems. In this project, we proposed a compact, on-axis liquid crystal on silicon (LCoS) illumination scheme with local dimming that leverages the polarization selectivity of a polarization volume grating (PVG) layer, which simultaneously serves as an analyzer for the LCoS and an input coupler for the waveguide in this design.
This work presents the fabrication process of the diffractive waveguide using a new photoalignment material (RN-4942) and a monocular demonstration of the proposed LCoS illumination design in a waveguide-based AR system. The proposed design improves the input-coupled and output-coupled optical efficiencies to <30% and <6%, respectively, enhances the contrast ratio, and achieves a total volume of <0.62 cc, including the projection optics, for a 1k × 1k LCoS panel.
Tajvidi Safa is currently a PhD student in Dr. Shin-Tson Wu’s Photonics and Display group.