  We experimentally demonstrate the in-situ characterization of optical
micro/nano fibers (MNFs).The MNF (test fiber, TF) is positioned on a microfiber
(probe fiber, PF) and simulated for the scattering loss at various PF and TF
diameters. The TF is fabricated using chemical etching technique. The PF is a
conventional single-mode fiber with an outer diameter of 125 um. We measure the
scattering loss along the TF axis at various positions i.e. diameters by
mounting it on the PF. The diameter profile of the TF is inferred from the
measured scattering loss and correlated with its surface morphology
measurement. This work demonstrates an effective, low-cost, and non-destructive
method for in-situ characterization of fabricated micro/nano fibers (OMNFs). It
can detect and determine the irregularities on the surface of OMNFs. It can
also be used to quantify the local evanescent field. Detecting such local
points can improve studies that are carried out using these fields in various
sensing and related study domains. It is simple to implement and can be
accessed by all domains of researchers.
