An integrated surface-plasmon source

Abstract

A compact and versatile source of coherent surface-plasmon polaritions (SPPs) is demonstrated by end-coupling a laser diode operating at 1.46 microm to a plasmonic waveguide integrated on the same microchip. With an optimized overlap between the spatial-modes of the laser and a planar-stripe waveguide, a high coupling efficiency of approximately 36% is achieved, that computations show could approach approximately 60% with smaller, readily achievable gaps between laser and waveguide. This integrated and electrically-activated source, with an available SPP power limited only by the laser diode, appears ideally suited for directly driving plasmonic circuitry or surface-enhanced sensors.

Efficient end-fire coupling of surface plasmons in a metal waveguide

“…Expanding the Eqs (34) in terms of Eqs (4), (13) and (16), and likewise expanding (35) in terms of Eqs (7), (14) and (20)…”

“…End-fire coupling was then successfully used in the laboratory by Charbonneau et al in 2000 to couple λ = 1.55 µm wavelength light onto a 3.55 µm Au strip on SiO 2 [11]. Since then, end-fire coupling has been shown to be an effective way of coupling SPs into more complex geometries, such as into waveguide-like nanocavities [12], in and out of dielectric and plasmonic waveguides [13][14][15][16][17][18], between nanowires and nanofibres [19,20], and photonic crystal fibres [21]. SP modes inside the finite nanocavities were studied theoretically by Al-Bader et al [22] and then explored both theoretically and experimentally by Kurokawa et al [12], though neither modelled the end-fire coupling step.…”

Efficient end-fire coupling of surface plasmons on flat metal surfaces for improved plasmonic Mach-Zehnder interferometer

“…26 In recent experiments, an approximate 30% coupling efficiency was obtained by using end-fire coupling to excite SPPs on flat metal films. 27 A numerically optimized coupling efficiency of 60% was believed to be achievable. 27 However, an understanding on the theoretically optimized efficiency for this coupling mechanism is still missing, which will be addressed in this work.…”

“…27 A numerically optimized coupling efficiency of 60% was believed to be achievable. 27 However, an understanding on the theoretically optimized efficiency for this coupling mechanism is still missing, which will be addressed in this work. Here we start from analyzing the scattering of an SPP mode from the output edge of a rectangular metal film, as shown in Fig.…”

Mid-infrared field concentration of electrically generated surface plasmons polaritons

“…A metallic waveguide is fabricated in the near-field of the QC laser facet, allowing direct excitation/injection of a SPP mode onto the metal-air interface. A similar approach has been recently employed in Reference [11] at an operating wavelength of 1.46 μm. In fact, the importance our work stems from the unavailability of cheap optical fibers operating at mid-IR frequencies.…”