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Surface plasmon resonance sensing in the advanced physics laboratory

We present a set of experiments and computations suitable for introducing upper-level undergraduate physics and engineering students to the interdisciplinary field of nanoplasmonics for periods ranging from a week-long advanced laboratory session to a summer research project. The end product is a tunable optofluidic device capable of detecting changes in a fluid medium as low as 0.002 refractive index units. The sensing element—a thin gold film on a glass prism coupled to a microfluidic cell—owes its sensitivity to the bound nature of the surface plasmon–polariton waves that are resonantly excited by evanescently coupled light at the gold–fluid interface. Pedagogically, surface plasmon resonance (SPR) sensing immerses students in the rich physics of nanoscale optics and evanescent waves in constructing and operating a precision apparatus and in developing theoretical, analytical, and numerical models to aid both in the physical understanding and engineering optimization of the SPR sensor.