Reconfigurable NIR-emission gain via thermal control in multimode tri-doped tellurite fiber

In fiber-based telecommunication systems, information is transmitted over wide optical spectrum bands. However, the volume of data, service demands, and traffic speeds keep rising, overloading the whole fiber links. Thus, enhancing efficiency and broadening transparency are essential in optical systems. Moreover, preserving gain across the broad spectrum remains a significant bottleneck to be overcome. Here we enhance intensity and broaden emission in the C-, L- and U- telecommunication bands via thermal population control in 30 cm of a tri-doped (Er³⁺-Tm³⁺-Yb³⁺) multimode tellurite fiber (3Dp-MM-Te-fiber). The results indicate that increasing the temperature, a blue shift occurs around 1530 nm, and due to energy transfer among the tri rare-earths dopants a flat gain in the near-infrared region up to 1550 nm to 1650 nm is observed with a bandwidth of more than 100 nm. Furthermore, pumping the fiber at 980 nm with a 0.1 mW signal at 1550 nm, an experimental relative gain of approximately 2.5 dB was also demonstrated at a 120 ^oC heating temperature.