Scanning near-field optical microscopy (SNOM) has gained wide interest as a viable microscopic technique for the study
of surface properties at the nanoscale. SNOM uses optical fiber to detect evanescent wave which provides a high
resolution imaging beyond the diffraction limit. The collected intensity is influenced by complex refractive index of the
sample. This project exploits the property of evanescent wave to discriminate between unhybridized and hybridized
DNA which has a significant difference in complex refractive index. The concept could become a promising alternative
since it circumvents fluorescence-labeling problems. The research focuses on numerical modeling by mean of finitedifference
beam propagation and DNA hybridization based on empirical data from literatures.