Expanding light from a waveguide into air
This mode expansion device is made of a linear waveguide, a slab waveguide, and a grating. Light enters the device through the linear waveguide. When the waveguide makes contact with the slab, the light expands laterally. The grating then converts the expanded light into waves through free-space. The process can also happen in reverse, bringing free-space light into the waveguide. This enables researchers to connect two mode expansion devices together. For instance, they can use two devices to prove an unknown gas.
November 2018 • NIST • https://www.nist.gov/news-events/news/2018/11/new-device-widens-light-beams-400-times-broadening-possibilities-science • Tagged: Animation
An early planning sketch: