Photonics is the broader design space where geometry, refractive index, fabrication limits, and performance targets all interact. I use this tag for posts that are less about a single lens or imaging path and more about how structure can be chosen to make light behave in a particular way.

It is the tag where I want to connect intuition and engineering: waveguides, metasurfaces, resonators, filtering, sensing, and other cases where light response is inseparable from the structure that produces it.

Start here:

• Photonics: Designing Light with Structure
• More on Optics

If you want the neighboring viewpoint, see Optics.