Dielectric microelements with circular symmetry have shown interesting optical properties: photonic nanojets (PNJs) and whispering gallery modes (WGMs). They can confine light inside the cavity, forming WGMs, or focus the light in their proximity, forming PNJs. Both WGMs and PNJs have found numerous applications, including sensing and imaging. In this work, a review of PNJs and their applications in contemporary literature is provided.

中文翻译：

---

光子纳米射流及其应用

具有圆形对称性的介电微元素已显示出令人感兴趣的光学特性：光子纳米射流（PNJ）和耳语画廊模式（WGM）。它们可以将光限制在腔体内，形成WGM，或者将光聚焦在它们附近，从而形成PNJ。WGM和PNJ都发现了许多应用，包括传感和成像。在这项工作中，提供了PNJ及其在当代文学中的应用的综述。