Nanoplasmonics and Metamaterials have in the last 15 years inspired scientists to think about photonics beyond traditional constraints imposed by natural materials in which light propagates to conceive functionalities such as subwavelength imaging and broadband ultraslow light. While most concepts have initially been demonstrated at longer wavelengths and for microwaves, they have continuously moved to optical frequencies and beyond. Embracing nonlinearity and (quantum) gain [1], exciting phenomena such as ‘dark-light’ [2] and cavity-free [3] nano-lasing and room temperature single...
