Nondestructive measurement of nanofiber diameters using microfiber tip

We demonstrate a convenient and simple method to determine nanofiber diameters nondestructively using a hemispherical microfiber tip probe. For a fixed-tip geometry and working wavelength, the scattering losses of nanofiber transmission induced by the tip are a function of the nanofiber diameter, while being insensitive to the alignment. Therefore, the nanofiber diameter can be estimated based on the measured nanofiber transmittance and the loss-diameter relationship that are obtained by three-dimensional numerical simulations. The method is experimentally demonstrated with a diameter measurement precision of 9.8 nm (1.5% of the measured diameter), and the results agree with those obtained by other methods. Such a nondestructive near-field probe approach offers a reliable and convenient technique for determining nanofiber diameters, with applications ranging from optical sensing to quantum optics to quantum information processing.