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The movement of magnetic nanoparticles (NPs) can be controlled by an external magnetic field. And Fe 3 O 4 @M (M = Ag or Au) core-shell NPs can exhibit both magnetic and plasmonic properties simultaneously. In this article, we theoretically proposed a plasmonic coupled nanolaser with tunable wavelength in full visible light range based on Fe 3 O 4 @M (magnetic-plasmonic) core-shell NPs/metal film coupled structure. We investigated the optical properties of the plasmonic coupled nanolasers with different core-shell NP sizes and gap distances between Fe 3 O 4 @M NPs and metal film by the finite element method (FEM). By controlling the gap distance and NP size, the wavelength of the plasmonic nanolaser based on Fe 3 O 4 @Ag NPs/Ag film coupled structure could be tuned from 415 to 810 nm, and that based on Fe 3 O 4 @Au NPs/Au film could be tuned from 536 to 779 nm. This work provides us a theoretical basis to real-time tune the wavelength of the plasmonic coupled nanolaser based on a liquid gain environment under an external magnetic field. • Magnetic-plasmonic nanolaser based on a coupling between LSP and SPP was designed. • Fe 3 O 4 @M (M = Ag or Au) core-shell NPs/metal film coupled structure was developed. • Optical properties with different NP sizes and gap distances were studied. • SPASER wavelength can be tuned in a range of 40–98 nm by changing gap distance. • Wavelength tunable range was extended to full visible region by changing NP size. [ABSTRACT FROM AUTHOR]

We propose a low threshold and wavelength tunable plasmonic coupled nanolaser based on a plasmonic coupling between Au nanosphere and Au film. By the finite-element method, we investigate the optical properties of the plasmonic coupled nanolaser with different nanosphere diameters and gap distances between Au nanosphere and Au film. The optical cross section of the plasmonic nanolaser based on the coupled nanostructure can be 60 times larger than that based on an independent Au nanosphere. And the corresponding gain threshold of the plasmonic coupled nanolaser is only 35% of that of the nanolaser with the independent Au nanosphere. This is attributed to that the coupled nanostructure exhibits a stronger electric field and optical intensity than the independent Au nanosphere, it can more effectively improve gain to compensate for metal loss. In addition, the plasmonic coupled nanolaser also exhibits a wavelength tunability in a wide spectral range by controlling the Au nanosphere diameter and gap distance between Au nanoparticle and Au film. This work can provide us an effective way to develop the on-chip application of nanolaser. • A plasmonic coupled nanolaser based on a coupling between LSP and SPP is designed. • The optical cross section is 60 times larger than that based on Au nanosphere. • The gain threshold is only 35% of that of nanolaser with independent Au nanosphere. • Coupled nanostructure exhibits a stronger electric field than Au nanosphere. • SPASER wavelength can be tuned by varying Au nanosphere diameter and gap distance. [ABSTRACT FROM AUTHOR]