Surface plasmon polaritons (SPP) play a key role in many research applications and devices [1]. To couple SPP from a free-space wave, by matching their wave vectors (momentum), a Prism or a periodic grating are frequently used. However, by these methods, only a single wavelength at a specific angle can by coupled into a single SPP.
We show that quasiperiodic grating enable the coupling of light at multiple wavelengths and angles. The quasiperiodic grating was designed in a systematic manner using the dual-grid method (DGM) [2]. The robust DGM algorithm allows us to control the coupling strength and grating dimensions for almost any arbitrary set of wave vector mismatches. We verified the method experimentally by efficiently coupling light into a surface plasmon from several different illumination angles using a single quasiperiodic grating [3]. This SPP coupling technique can be used for a wide range of applications where multiple coupling conditions are required, such as biochemical SPP sensors, nonlinear optics, and other SPP subwavelength optical devices.
Written by: Ido Dolev
References:
[1] S. A. Maier, Plasmonics: Fundamentals and Applications (Springer, 2007).
[2] R. Lifshitz, A. Arie, and A. Bahabad, Phys. Rev. Lett. 95, 133901 (2005).
[3] I. Dolev, M. Volodarsky, G. Porat and A. Arie, Multiple coupling of surface plasmons in quasiperiodic gratings, Optics Letters, 36, 1584-1586, (2011).
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