Optics in 2022 and Beyond

I was recently asked to contribute to Optics & Photonics News a short paragraph on predictions on what will be the biggest advances in topological photonics in 2022. Here are my initial thoughts (to be refined):

Prominent trends in 2021 have been:

• Demonstrations of topological defect modes including Jackiw-Rossi modes and free-form disclination waveguides.
• Increased interest in topological designs among non-specialists in topology, studying important questions including how to quantify scattering losses of topological waveguides (e.g. due to sidewall roughness), how to efficiently couple between topological and non-topological modes, and the design of functional components such as power splitters, directional couplers, and absorbers using topological modes.
  
• Many theoretical and experimental studies of nonlinear and quantum effects in topological systems, including topological lasers and frequency combs.
• Optical fiber loops and 3D printed waveguide arrays and photonic crystals have emerged as flexible new platforms for implementing topological models. Most prominently, the former has allowed the first demonstration of various non-Hermitian topological effects. At the same time, the surging interest in quantum computing (in particular photonic approaches) mean that equipment for probing topological wave systems with quantum states of light should become cheaper and more accessible in the near future.
• Links between topological photonics and other hot topics (bound states in the continuum, structured light, singular optics, transformation optics, leaky mode theory) are becoming better-appreciated.

Already a few years ago there were discussions at conferences on how the field is starting to mature, meaning that some useful practical applications of topological photonics need to be demonstrated to sustain interest among researchers, high impact journal editors, and funding agencies. Therefore I think in the coming year there will be a growing focus on demonstrating topological waveguides and cavities with superior performance compared to conventional designs using well-established figures of merit.

I would like to focus on a specific application (e.g. lasers or integrated waveguides) to give my final paragraph more of a punch.

Did I overlook any important lines of research? I welcome comments and criticism.