Microresonator array for high-resolution spectroscopy

We investigated the properties of an array of spherical microresonators used as a miniaturized high-resolution spectroscopic device. Sixteen spherical microspheres made from polymethyl methacrylate were placed on a microscope slide serving as an optical wave guide. Light of a tunable narrowband laser source was coupled into this slide so that an evanescent wave was excited on the topside of the slide, where the resonators were placed. This evanescent field generated a particular intensity pattern in the array that depended sensitively on the wavelength. After calibration, that pattern was recorded by a CCD camera and used to identify the wavelength with a resolution of R ~ lambda/Deltalambda = 7 x 10(4).