A few optics/metamaterials highlights from META 2026

This past week I attended META 2026, the 16th International Conference on Metamaterials, Photonic Crystals and Plasmonics, at Trinity College, Dublin.  This was the first time I've ever gone to this conference, which has grown from somewhat blurry beginnings to a ~ 900+ person annual event.  Here are a few scientific highlights:

• Metasurfaces, built up from spatial arrays of dielectric (or sometimes semiconductor or plasmonic) resonators called "meta-atoms", have matured into very impressive, versatile tools.  In her plenary talk, Ruwen Peng from Nanjing showcased different approaches, combining angularly rotated meta-atoms ("Pencharatnam-Berry") and size-modulated meta-atoms.  The result can produce polarization-entangled photon beams, entangle photon spin and orbital angular momentum for quantum key distribution, and do full entanglement distribution over many channels.  Similarly, Federico Capasso gave a very impressive talk about the progress in the field, from visible wavelength flat optics ten years ago to compact platforms for sophisticated quantum tomography.
• Nikolay Zheludev gave a great overview about combining measurements + machine learning estimators (e.g., here) to achieve effective optical resolution far better than conventional limits.  This can be used to make optics-base estimates of nanowire lateral displacements down to the 100 pm level, for example.  Rather than looking at the flow of energy in an optical imaging system, one can look at the flow of Fisher information regarding the object being imaged.
• There were a series of talks throughout the meeting about chirality of optical scattering, what this means, and what it can lead to (including enantiomer-selective imaging and chemistry).  Note that it's important to distinguish between intrinsic chirality (e.g., the object scattering the light has a real structural handedness), extrinsic chirality (the object scattering the light is not chiral, but the experimental arrangement to do and measure the scattering introduces chirality into the measurement), and chirality in the fields themselves (think swirling Poynting vectors locally) that don't necessarily extend to the far field.  There are some neat probes of local effects, like this use of local polymerization.
• Roman Quidant gave a talk about metalenses that are also optomechanical structures (e.g., use a pump beam to excite mechanical deformation of the metalens to steer the focus of a probe beam).  This lets you do some pretty neat things, like control the sign of optical forces by dynamically tuning the relative importance of momentum transfer (pushing objects with light by direct momentum kick from photons) and polarization forces (the classical optical tweezer situation where polarizable objects "seek" regions of high intensity).  This can enable feedback control to do optical cooling of trapped, levitated particles, potentially down to the quantum level.
• Alessandra Boltasseva presented a variety of recent advances, including a look at how plasmonic ceramics like TiN and HfN have properties that can be dramatically tuned as their thickness gets down to the few-unit-cell level, a regime she and collaborators term "transdimensional" (to distinguish from atomically thin 2D van der Waals materials).  The possibility of Wigner crystallization in such systems is exciting, though disorder is a likely complication.  

• 

  A 4-channel wavelength division multiplexer
  made from etched Si3N4, from this paper.

  Jeremy Baumberg talked about building metamaterials out of molecularly-spaced nanoparticles, and how this has opened up real opportunities for chemical sensing based on surface-enhanced Raman and infrared absorption, as in this example.  Neat stuff.
• There were multiple talks about metasurfaces for nonlinear optics, including one by Igal Brener on cool ways to use GaAs metasurfaces to produce entangled photon pairs via bound states in the continuum.  
• Likewise, there were a number of presentations about inverse design, where computational tools are used to produce very funky looking structures which can act as, e.g., multichannel routers of optical signals.  Jelena Vuckovic presented an overview of this, showing how it can be done at scale to produce a chip that acts as a 1 TB/s optical router.  Structures produced this way always seem to me like some kind of eldritch geometry out of HP Lovecraft (see figure), but they work.  
  

As always, apologies to those whose work I didn't mention above; my note-taking was pretty uneven.

(I am trying to strike a balance between talking and educating people about science, which is basically the point of this blog, and keeping people informed/voicing some of my personal opinions about the crisis in the US research ecosystem (arguably the most consequential challenge facing US researchers today, with long-term implications that will be felt for many years).  There is still very exciting work being done in nanoscience, the physics of materials, etc. - we are just facing a future where if current trends continue the major advances may increasingly happen outside the US.)