Sensitivity enhancement in optical micro-tube resonator sensors via mode   coupling
  A liquid filled, low refractive index material inner-coated silica micro-tube has been proposed and studied as a coupled micro-resonator sensor to greatly enhance biochemical sensor sensitivity. Its unique coupling phenomenon has been analyzed and utilized to boost the refractive index sensitivity of the device to 967nm/RIU. Through optimization of the coupling strength between the two microresonators, further improvement in refractive index sensitivity up to 1100nm/RIU has been achieved. This mode coupling strategy allows us to design robust, thick-walled micro-tube sensors with ultra-high sensitivity which is useful in practical biochemical sensing applications. 
Tao Ling, and L. Jay Guo
physics.optics