Active plasmonics
(Vasco Tenner, Martin van Exter)

frerik-randomholes Schematic setup: subwavelength holes (160nm) are spaced 450nm apart in a square array. These holes provide feedback for surface plasmon laser action. The optically pumped gain layer provides gain for the surface plasmon laser at telecom wavelengths. The output light is captured using a microscope objective and analysed.

Surface plasmons have their optical fields concentrated on a metal surface. Due to this strong confinement, most optical meta-materials are using surface plasmons. However, surface plasmons experience intrinsic ohmic losses in the metal. We use a very simple meta material (a metal hole array) on an active gain medium to compensated these losses and even observe lasing action.

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The aim of the project is to understand this lasing action inside the device and the resulting laser output. We obtain this by smart experimental observations and by modelling the laser action with simple equations to gain more insight. For this we characterize the laser behaviour. The radiated laser emission has a peculiar donut shaped beam profile. Furthermore we observed that the SP-laser is not radiating in the center of the device.