Tuning the emission color of a quantum emitter by using photonic local density of states.

Quantum emitters characterized by their emission colors constitute important elements in the design of modern nano-optics. Although we can change the emission colors of a quantum emitter by tailoring its chemical component, once selected, the color usually cannot be changed. It will be tempting to find out whether the emission color of an emitter could be tuned without touching its chemical component. In this Letter, we theoretically propose a strategy to externally tune the emission color of a model emitter by changing its electromagnetic environment. We found that the photonic local density of states (PLDOS) strongly affect the competition between various internal radiative and nonradiative channels, thus enabling a selective electronic state to dominate the emission spectrum. Indeed, quantitative calculations show that the emission color of a model emitter could be tuned from red to green and blue as the PLDOS increases. Moreover, due to direct correspondence between the emission color and PLDOS, the emitter can be potentially used as a sensor to characterize the local electromagnetic environment by its emission color at the nanoscale. This simple strategy may prove to be useful in the future design of various nano-optical devices.