An Optical-Fiber-Based Key for Remote Authentication of Users and Optical Fiber Lines.

We have shown the opportunity to use the unique inhomogeneities of the internal structure of an optical fiber waveguide for remote authentication of users or an optic fiber line. Optical time domain reflectometry (OTDR) is demonstrated to be applicable to observing unclonable backscattered signal patterns at distances of tens of kilometers. The physical nature of the detected patterns was explained, and their characteristic spatial periods were investigated.

Interferometric technique for investigation of nonradiative transition kinetics in silica-fiber laser media.

A novel tool for investigation of nonradiative processes in active solid-state laser media is proposed. The technique is based on using an interferometer for population-kinetics detection by means of resonantly enhanced nonlinearity. The advantages of this method in comparison with traditional luminescence-kinetics techniques are verified on the example of decay time measurements for nonradiative 4I(11/2)→4I(13/2) transition in an Er3+-doped active optical fiber.