Ultra-narrow optical features with a spectral bandwidth below 1 megahertz are highly sought-after for applications in ultrahigh-precision sensing, narrow-band filtering, and information storage for optical computing - but unfortunately they are extremely challenging to generate. But now there is a novel way to achieve ultra-narrow optical features. And unlike conventional approaches, it is cost-effective, has a simple arrangement, and is loss-free, while offering on-demand tunability and ...
