Enhanced broadband upconversion emission and 23Â dB optical gain at 780Â nm in Tm3+/Nd3+ codoped optical fiber

Maximum gain of 23 dB at 780 nm and a broadband optical gain with full width at half maximum (FWHM) of 88 nm (761-849 nm) were obtained from the Tm3+/Nd3+ codoped fiber upon pumping at 1550 nm. The enhancement of the upconversion emission stretching from 730 to 970 nm was observed in the Tm3+/Nd3+ codoped fiber due to the energy transfer from Tm3+ to Nd3+ ions.