Observation of evanescent field from the waveguide with liquid cladding by the near-field scanning optical microscope

초록

We utilized the near-field scanning optical microscope (NSOM) to measure the evanescent field near the core-cladding interface of a channel waveguide with a liquid cladding. Since the cladding region of waveguides was often composed of a solid material, one could not approach the fiber tip close to the core-cladding interface, and not observe the evanescent field from the real devices. However, by filling the core region with the index matching liquid instead of the solid cladding, we could observe the evanescent field near the interface and understand the propagation characteristics of realistic waveguide devices