Optical Microring Resonators Constructed from Organic Dye Nanofibers and Their Application to Miniaturized Channel Drop/Add Filters

We fabricated micrometer-scale optical ring resonators by micromanipulation of thiacyanine (TC) dye nanofibers that propagate exciton polaritons (EPs) along the fiber axis. High mechanical flexibility of the nanofibers and a low bending loss property of EP propagation enabled the fabrication of microring resonators with an average radius (r(ave)) as small as 1.6 mu m. The performances of the fabricated resonators (r(ave) = 1.68.9 mu m) were investigated by spatially resolved microscopy techniques. The Q-factors and finesses were evaluated as Q approximate to 3003500 and F approximate to 212. On the basis of the r(ave)-dependence of resonator performances, we revealed the origin of losses in the resonators. To demonstrate the applicability of the microring resonators to photonic devices, we fabricated a channel drop filter that comprises a ring resonator (r(ave) = 3.9 mu m) and an I/O bus channel nanofiber. The device exhibited high extinction ratios (46 dB) for its micrometer-scale dimensions. Moreover, we successfully fabricated a channel add filter comprising a ring resonator (r(ave) = 4.3 mu m) and two I/O bus channel nanofibers. Our results demonstrated a remarkable potential for the application of TC nanofibers to miniaturized photonic circuit devices.