An open-accerss journal, Applied Sciences (EISSN 2076-3417, IP2018 = 2.217), published by MDPI AG, announces the publication of its focus issue, "Active nano-Optics". Two members of the Photonics Center, Brana Jelenković and Branko Kolaric, have been appointed to serve as guest editors of this issue. Their message as guest editors can be retrieved from the flyer.