Gold nanoshells with gain-assisted silica core for ultra-sensitive bio-molecular sensors

A novel bio-molecular nanostructured sensor composed of Au spherical nanoshell and gain-assisted silica-core has been proposed and investigated theoretically, which shows a superior performance compared to the existing structured sensor. Using quasi-static approximation calculation, it is found that the scattering efficiency and the quality factor of SPR can be enhanced greatly by introducing proper amount of gain. The simulated results demonstrate that our designed Au spherical nanoshell and gain-assisted silica-core can obtain as high as 166.7 nm/RIU for the sensitivity of refractive index, and the sensors' figure of merit is enhanced 2000 times nearly compared to that of g=0, which indicates that the designed spherical core–shell sensors have the powerful ability to detect a subtle change in the concentration of its background medium.