Biophotonic sensor applications based on photonic atoms

Microsphere resonators, i.e., photonic atoms, have found wide area of application in optical spectroscopy, quantum optics, cavity QED, switching, and sensing. Photonic atoms have unique optical properties such as high quality factor (Q-factor) morphology dependent resonances (MDR's), and relatively small volumes. High-Q MDR's are very sensitive to the refractive index change and microsphere uniformity. These tiny optical cavities, whose diameters vary from a few to several hundred micrometers, have resonances with reported Q-factors as large as 3x10(9). Due to their sensitivity, MDR's are also considered for biosensor applications. Binding of a protein or other biomolecules can be monitored by observing the wavelength shift of MDR's. A biosensor, based on this optical phenomenon, can even detect a single molecule, depending on the quality of the system. In this work, elastic scattering spectra from photonic atoms of different materials are experimentally obtained and MDR'S are observed. Preliminary results of unspecific binding of biomolecules are presented. Elastic light scattering spectra of MDR's for biosensor applications are calculated numerically for biomolecules such as Bovine Serum Albumin (BSA) and for Deoxyribo Nucleic Acid (DNA).