Generalization of the Rouard method to an absorbing thin-film stack and application to surface plasmon resonance

Numerical Optimization of Plasmonic Biosensors

“…The minimum of R depends on the thickness of the gold layer, therefore this parameter has to be optimized, to increase the efficiency of the biosensor in terms of contrast in R.T h e figure 2(b) shows the effect of a slight change in the optical index of the medium of detection n 3 : the position of the minimum is shifted toward larger angles. Therefore, to detect a change in the optical index n 3 of the above medium, the measurement of the shift of θ, corresponding to R ≈ 0 is achieved (Bonod et al, 2003;Lecaruyer et al, 2006). This setup is also called Kretschmann configuration (Kretschmann, 1978) and is an object of study for undergraduates, as r and t can be easily calculated (Simon et al, 1975).…”

“…Since the engineering control of the deposition of nanometric gold plates on substrates the Surface Plasmon Resonance (SPR) based sensor has become one of the most successful label-free and commercially developed optical sensor, with applications to biology (Hoaa et al, 2007;Kolomenskii et al, 1997;Kretschman & Raether, 1968;Lecaruyer et al, 2006). This technique is currently employed in biomolecular engineering, drug design, monoclonal antibody characterization, virus-protein interaction, environmental pollutants detection, among other interesting problems.…”

“…This technique is currently employed in biomolecular engineering, drug design, monoclonal antibody characterization, virus-protein interaction, environmental pollutants detection, among other interesting problems. The basic principle of such transducer is the measurement of the sudden absorbtion of light by the thin metallic layer, under particular illumination conditions (p-polarization) and a specific angle of incidence of the illumination (Barchiesi, Kremer, Mai & Grosges, 2008;Barchiesi, Macías, Belmar-Letellier, Van Labeke, Lamy de la Chapelle, Toury, Kremer, Moreau & Grosges, 2008;Kretschman & Raether, 1968), leading to a highly sensitive device (Kolomenskii et al, 1997;Lecaruyer et al, 2006). The conditions of such absorption are linked to the plasmon resonance in metallic structure, and therefore a tiny change of the optical properties of medium above the gold plate, produces an angular shift of this absorption, due to the detuning of the resonance.…”

“…Therefore, to improve the efficiency of the sensor, the material and geometrical characteristics of the materials involved in the biosensor must be adjusted correctly. Surprisingly, the optimization of such structures has rarely been addressed (Ekgasit et al, 2005;Kolomenskii et al, 1997;Lecaruyer et al, (Barchiesi, Macías, Belmar-Letellier, Van Labeke, Lamy de la Chapelle, Toury, Kremer, Moreau & Grosges, 2008). Thus, the numerical optimization is becoming a useful tool, especially with the aim to apply to the optimization of nanostructured biosensors for which a large number of parameters has to be adjusted, making unapplicable a classical experimental design plan.…”

Infrared imaging using arrays of SiO_2micromechanical detectors

“…Compared to previous work [9], an additional photolithography step was introduced in order to create the optical cavity within the detectorabsorbing region. The thickness of the optical cavity was optimized using a generalized Rouard method [13]. The optical cavity is formed by the layer of amorphous Si embedded between the SiO 2 and Al layers, and its thickness determines the IR-wavelength region, which in this work was centered at 10 μm [14].…”