The development of high sensitivity surface plasmon resonance (SPR) sensor depends on few crucial factors such as types and thicknesses of metal thin films, light coupling techniques and suitable polarization modes of EM waves. This work was carried out to investigate the effect of EM wave polarization modes on the sensing properties of SPR sensor in detecting heavy metal ions namely mercury (Hg) and plumbum (Pb). Three types of light polarization modes such as p-polarized, s-polarized and circular-polarized light were introduced. Gold and silver thin films with thicknesses of 50nm were deposited on top of SPR layer system to excite surface plasmon polaritons (SPPs). The SPR curves were analyzed by studying the FWHM, Q-factor and angle shifting characteristics. We managed to prove theoretically that the SPR phenomena able to be created by using not only the p-polarized light, yet by employing a circular-polarized light. The sensor showed positive respond for both polarization modes, where the troughs were red-shifted about 23.78% as Pb was introduced on the top of the gold-coated SPR sensor. The SPR angles were shifted about 24.45% as the sensor was exposed with Hg metal ions. Different response due to the presence of different analytes exhibited excellent criteria of high selectivity sensor. In conclusion, the combination of p-polarized light or circular-polarized light and gold thin film able to accentuate the significant role of SPR sensor in detecting heavy metal ions.

Gold nanoparticles (GNPs) have been known as an excellent characteristic for Local Surface Plasmon Resonance (LSPR) sensors due to their sensitive spectral response to the local environment of the nanoparticle surface and ease of monitoring the light signal due to their strong scattering or absorption. Prior the technologies, GNPs based LSPR has been commercialized and have become a central tool for characterizing and quantifying in various field. In this review, we presented a brief introduction on the history of surface plasmon, the theory behind the surface plasmon resonance (SPR) and the principles of LSPR. We also reported on the synthetization as well of the properties of the GNPs and the applications in current LSPR sensors.