Surface light propagating in a dielectric thin film generated via micro-spheres

Light orbiting through total internal reflection within dielectric spheres or disks is called the whispering gallery mode (WGM). Recently, we have reported anomalously enhanced Raman spectra at the periphery of 3 µm diameter polystyrene (PS) microspheres on a silicon nitride (SiN) film using Raman microscopy. Here, we performed Raman measurements and optical simulation analysis of 3 µm PS spheres on a SiN film using a three-dimensional (3D) model and found that the circumferential light was generated up to 650 nm from the outer circumference of the sphere. Furthermore, a portion of the light circling the sphere travelled to the SiN film and became surface propagating light. These properties are expected to lead to development of new devices such as highly sensitive sensors, quantum optical qubits, and optical integrated circuits.