Dec. 2021 – Physics-Informed Machine Learning represents a novel tool for combining the benefits of analytical theory and pattern-recognition-based machine learning. Physics-informed models train faster and perform better than their science-agnostic “black box” counterparts – see arXiv and associated codes.
Oct. 2021 – UML-lead team is among the recipients of NSF DMREF awards – class 2021.
Nov. 2020 – Ballistic Metamaterials – a new resonance resulting from the interplay between free charges in ultrathin layers and time-periodic electromagnetic field provides the avenue for plasma-like response above plasma frequency – see full manuscript
Nov. 2018 – Structural second harmonic generation represents a new way to engineer strong nonlinear response in composite materials – see press-release by UML or full manuscript
Aug. 2016 – Interscale Mixing Microscopy is demonstrated to enable far-field spectroscopy of nanoscale objects. The new technique can become a new characterization protocol for optically small objects – see press release by UML or full manuscript
Feb. 2013 – Metamaterials for ultrasound – see press releases by UML and TAMU A class of optical metamaterials, nanowire composites, is shown to dramatically improve ultrasound detection.
Nov. 2012 – Beaming in plasmonic crystals Further development of medicine, biology, security, computations, and many other technologies requires the ability to see the objects in ever increasing details. Unfortunately, resolution of the majority of microscopes is fundamentally limited to about one half of the wavelength of light. In 2007 I. Smolyaninov and collaborators have fabricated a device, consisting of a set of ultra-small concentric rings deposited on thin gold film. The team demonstrated under right conditions a small, subwavelength, “bump†indented in the device would generate a beam of light that could be used to recover the size of the bump. The concentric ring structure became known as plasmonic magnifying superlens. However, despite exciting potential applications, the physics behind this phenomenon was not completely clear. Now S. Inampudi, a graduate student in the group of V. Podolskiy at U Mass Lowell, in collaboration with I. Smolyaninov have provided a solution to this long-standing puzzle. The researchers first developed a novel computational technique for analyzing the dynamics of optical waves propagating in the corrugated structures. They then identified the particular set of light waves that are routed by the corrugations to form the beams. Finally, the team provided a straightforward way to relate the novel optical properties of corrugated metallic films to the more familiar behavior of periodic optical structures known as photonic crystals. The result may become instrumental in designing of practical devices based on corrugated metallic structures. The results of the study, supported by the National Science Foundation, are published in Optics Letters, a professional journal.
Sep. 2011 – Funneling light through ultra-small openings gives a new hope for compact all-optical systems We experimentally demonstrate, at optical frequencies, the phenomenon of extraordinary light funneling through a subwavelength slit using material with vanishingly small refractive index and present an analytical explanation of the underlying physics. Efficient coupling of light to ultra-small, subwavelength features is a fundamental problem of optics that prevents further miniaturization of optical sensors, optical guides, and ultra-high-speed communication and computation systems. Until recently, the most efficient way to transfer radiation through subwavelength openings was to fill the opening with a high refractive index material, thereby decreasing the wavelength of light inside the slit. In 2006 it was theoretically proposed that replacing the high-index filling with a material with small, near-zero refractive index (also known as epsilon-near-zero or ENZ material) could result in perfect light transmission through an arbitrarily small hole, though it was conceded that this phenomenon would be limited by absorption inside the ENZ medium. In this work we demonstrate, experimentally and theoretically, that realistic (lossy) ENZ materials can substantially increase light coupling to subwavelength features at optical frequencies, even when compared to their low material-loss, high-index counterparts. Our work demonstrates the feasibility of a new avenue for connecting emerging ultra-compact optical systems to their well-developed but less-compact counterparts
