Response of Photonic Devices

When light hits the surface of a photonic device, such as an optical biosensor, the light travels through and is modified through the optical resonators within. The light that enters these microring resonators through an input port are split into transmitted and reflected components.  Transmitted light passes through the output port, while reflected light exits from the same input port. This is due to the inherently different refractive indices present between the medium in which the light travels and the medium in which the light hits. Mathematically, the transmitted and reflected components are described by the Fresnel equation, after the French scientist, A.J. Fresnel (1788-1827).

Figure 1. A ring resonator in an aqueous solution. (a) There are no bioparticles in the solution, and the resonance wavelength of the resonator is shown on the left. (b) Bioparticles are present, and the resonance wavelength is shifted.