Researchers propose and demonstrate an optical black hole cavity based on transformation optics

Whispering-gallery-mode (WGM) cavities represent an intriguing platform for intensely enhancing light-matter interaction. It lays the foundations for ultra-low threshold lasers, ultra-sensitive sensing, nonlinear optics and quantum photonics. The conventional WGM cavity is composed of homogeneous materials with a constant refractive index both in the core and cladding. The light field is confined in the cavity through the total internal reflection (TIR) and enhanced through constructive interfer...