Design and Investigation of PCF based Highly Sensitive Surface Plasmon Resonance Biosensors

Abstract

Due to SPR based PCF possessing numerous advantages, researchers have focused on improving the design of these sensors. As a result, sensors with better sensing performances are discovered and some are on the way to be discovered. While designing the sensors researches focused on choosing the appropriate plasmonic material, easier fabrication process, better sensing approach. Their main concerns were to design such sensors which could be practically implemented. In order to get better sensing performance, the sensor design becomes complex. So difficulty while fabricating can be faced. We tried to propose three designs for our thesis paper which gave us satisfying results .We also tried to focus on reducing the problems faced. In our first design, we proposed a circular lattice structure with gold coating. Our proposed design was surrounded with a thin PML layer. We tried to optimize various parameters like gold, PML, airholes and chose the values which gave us the best result. In our second design we proposed a highly sensitive SPR based PCF biosensor in which we used gold as the plasmonic material. We adapted stack and draw method for designing the propose sensor so that fabrication becomes easier. For this proposed design also we tried to optimize various parameters and chose the values which gave us the best results. In our last proposed design we tried to explore the sensitivity performance as well as the temperature sensitivity performance. In all cases we used COMSOL Multiphysics 5.3a and Matlab for our researched work. The sensing outputs of the proposed designs were explored by Finite Element Method (FEM). Our first proposed design gave the amplitude sensitivity of 1779 RIU-1 , 407 RIU-1 and wavelength sensitivity of 3000 nm/RIU, 2000 nm/RIU in x and y polarization modes respectively. In this case analyte refractive index (RI ) was varied from 1.32 to 1.37 accordingly. This design gave a minimum amplitude sensor resolution of 5.6210-6 and a minimum wavelength sensor resolution of 3.3310-5 . We also obtained a birefringence of 0.0049 and FOM value of 187.5..The second proposed sensor gave us the maximum wavelength sensitivity of 14,500 nm / RIU in X-polarization mode and the maximum amplitude sensitivity of 4738.9 RIU-1 for Y-polarized mode, respectively .The RI was varied in the range of 1.35–1.41 .This sensor gave the lowest wavelength sensor resolution of 6.9×10-6RIU and the lowest amplitude sensor resolution of 2.11×10-6RIU for Y-polarized mode with FOM of 387 and 364 for X and Y polarization. Our last proposed sensor gave us the amplitude sensitivity of 1432 RIU-1 and 1291 RIU-1 in X and Y polarized mode, respectively. It gave a wavelength sensitivity of 13,500 and 13,000 in X and Y polarized mode respectively. Sensor resolutions of 7.407×10-8 and 7.692310-8 were obtained using wavelength interrogation method and 6.983210-6 , 7.7459310-6 were obtained by using amplitude interrogation method in Y and X polarized mode respectively. FOM value of 521.4601 and 546.93 were obtained for X and Y polarization method. Birefringence of 1.5×10-3 was found for the proposed sensor. Temperature sensitivity for temp range (-114 to 78℃) was 4.5833 nm/℃. So after observing the results of our proposed sensors we can say that our sensors can be used for sensing purposes.