Self-Mixing Signal in ${\rm Er}^{3+}-{\rm Yb}^{3+}$ Codoped Distributed Bragg Reflector Fiber Laser for Remote Sensing Applications up to 20 Km

The self-mixing sensing technique is a compact sensing technique that can be used for measuring distances, displacements, velocities, and vibration. In this letter, for good sensitivity remote measurement, self-mixing interference using an Er
³⁺
-Yb
³⁺
Distributed Bragg Reflector (EYDBR) fiber laser is proposed and investigated for the first time. Results demonstrate that the EYDBR fiber laser presents a powerful tool for the self-mixing sensor and provides a remote measurement of the displacement and the vibration up to 20 Km.