Optical sensor based on surface plasmon resonance are widely used for various applications. In this paper, an optimization of EM waves polarization modes for the occurrence of SPR by using a modified optical waveguiding assembly has been discussed. A 633 nm of linearly polarized He-Ne laser was appointed as a light source. The polarization modes were controlled by rotating the position of He-Ne laser. It was found that the optimum SPR signal with reflectance, R = 0.21 a. u and SPR angle, theta(SPR) = 48 degrees can be obtained as the position of laser was rotated at 90 degrees, with the presence of polarizer. The location of the critical angle was observed at theta(C) = 46 degrees. For the validation purpose, a simulation based on Fresnel equation was conducted where the percentage difference between the experimental and theoretical results were analyzed. The percentage difference between experimental and theoretical results for both theta(SPR) and theta(C) were 9.09% and 15.00% respectively. In conclusion, an excellent agreement between the theoretical and experimental findings proved the stability of this SPR setup, where the EM waves polarization can easily be controlled by manipulating the position of laser.

Nowadays, surface plasmon resonance (SPR) sensor has been widely used in biosensing applications to detect the wide diversity of biomolecular interactions. There are few parameters need to be concerned in order to optimize the performance of SPR sensors such as film thicknesses, type of thin films and their configurations. In this study, we seek to determine the optimum thicknesses of hybrid thin films which consist of gold-graphene oxide layers for the enhancement of SPR sensor sensitivity. By using a theoretical approach, a WINSPALL 3.02 simulator had been used to investigate the effects of various thicknesses of hybrid configuration's thin films towards the excitation of surface plasmon polaritons (SPP). A layer of 3 nm protein was added to compare the maximum adsorption of the SPR sensor based on their configuration. It was found that the optimum thicknesses of gold and graphene oxide are 50 nm and 0.68 nm respectively for achieving best sensitivity. Thus, the sensitivity value for gold-GO thin films is higher than silver-GO which are 19.42 degrees/RIU and 5.45 degrees/RIU with FWHM = 2.28 degrees and 0.64 degrees respectively.