title: Gain-shift induced by dopant concentration ratio in a Thulium-Bismuth doped fiber amplifier.
abstract: This paper details the effect of Thulium and Bismuth concentration ratio on gain-shift at 1800 nm and 1400 nm band in a Thulium-Bismuth Doped Fiber Amplifier (TBDFA). The effect of Thulium and Bismuth's concentration ratio on gain shifting is experimentally established and subsequently numerically modeled. The analysis is carried out via the cross relaxation and energy transfer processes between the two dopants. The energy transfer in this process was studied through experimental and numerical analysis of three samples with different Tm/Bi concentration ratio of 2, 0.5 and 0.2, respectively. The optimized length for the three samples (TBDFA-1, TBDFA-2 and TBDFA-3) was determined and set at 6.5, 4 and 5.5 m, respectively. In addition, the experimental result of Thulium Doped Fiber Amplifier (TDFA) was compared with the earlier TBDFA samples. The gain for TBDFA-1, with the highest Tm/Bi ratio, showed no shift at the 1800 nm region, while TBDFA-2 and TBDFA-3, possessing a lower Tm/Bi concentration ratio, shifted to the region of 1950 and 1960 nm, respectively. The gain shifting from 1460 nm to 1490 nm is also observed. The numerical model demonstrates that the common 3F4 layer for 1460 nm emission (3H4→3F4), and 1800 nm emission (3F4→3H6)inversely affects the 1460 nm and 1800 nm gain shifting.
authors.forename: Siamak Dawazdah
authors.initials: SD
authors.lastname: Emami
authors.forename: Atieh
authors.initials: A
authors.lastname: Zarifi
authors.forename: Hairul Azhar Abdul
authors.initials: HA
authors.lastname: Rashid
authors.forename: Ahmad Razif
authors.initials: AR
authors.lastname: Muhammad
authors.forename: Mukul Chandra
authors.initials: MC
authors.lastname: Paul
authors.forename: Arindam
authors.initials: A
authors.lastname: Halder
authors.forename: Shyamal Kumar
authors.initials: SK
authors.lastname: Bhadra
authors.forename: Harith
authors.initials: H
authors.lastname: Ahmad
authors.forename: Sulaiman Wadi
authors.initials: SW
authors.lastname: Harun