Numerical investigations of metal-dielectric-metal waveguide-coupled dual nanoresonator is demonstrated. Phase dependent resonant behavior along with its complex plane analysis is investigated in wavelength regime. Detailed analysis of the influence of the structural parameters on the resonance curve helps to determine the correct device parameters for different plasmonic applications. This waveguide-coupled plasmonic resonator can be utilized for chemical and biological sensing. In this context, figure of merit related to the asymmetric Fano line shape is redefined, incorporating both differential phase and quality (Q)-factor. Theoretical analysis of differential phase sensitivity in wavelength regime predicts the possibility of detection of refractive index change of the order of 10-8 RIU. © 2015 IEEE.