Abstract:
In this work, an investigation is made to find an alternative material for metals in plasmonic devices in order to overcome the drawbacks of plasmonic devices formed using conventional plasmonic metals like gold and silver. The plasmonic devices formed with gold and silver have a number of limitations in dealing with optical losses, nanofabrication, tunability, chemical stability, and compatibility with conventional manufacturing processes. Thus, to find a suitable replacement, plasmonic properties of gold and silver are studied and materials with similar properties are searched. As a potential alternative material to gold and silver, heavily doped silicon is mathematically modeled and the theoretical model is compared with experimentally obtained data in order to verify the theoretical modeling. The verified model is compared with metals and the plasmonic properties of heavily doped silicon are found similar to those of metals. The material is then defined with the verified model and waveguide is formed using heavily doped silicon instead of metal. The transmission characteristics of the newly formed waveguide are compared with conventional gold and silver waveguide and the suitable material is selected for designing plasmonic devices. Two plasmonic refractive index sensors are investigated numerically and optimized for obtaining a better result. The first refractive index sensor has a highest sensitivity of 1208.9 nm/RIU and the other one has a highest sensitivity of 4900 nm/RIU which is the highest sensitivity reported for plasmonic refractive index sensor to the best of my knowledge. Both the sensors have resolution as small as 0.005. Moreover, the sensors have very simple structures, one with gratings in a straight waveguide and the other with a ring resonator and thus are suitable for being integrated in optical integrated circuits. However, the main advantage of these devices is that, they use only silicon instead of metals like gold or silver which makes them similar to SOI devices and thus, they become compatible with CMOS technology.
