• Bi-doped fiber was fabricated using MCVD process and solution doping method. • It operates efficiently as amplifier medium on short-wavelength side of the O-band. • The unsaturable losses were measured at different wavelengths. • The performances of this fiber were associated to lower unsaturable losses. • Emission lifetime measurements highlight inhomogeneous nature of Bi active center. The development of new optical fiber amplifiers is crucial to expand the communication capacity of existing fiber optic infrastructures. Herein, we present results on a Bismuth-doped phosphosilicate fiber intended for optical amplification in the short-wavelength side of the O-band. This W-type fiber was fabricated using Modified Chemical Vapor Deposition technique combined with solution doping method. Under 1195 nm pumping, it achieved a gain superior to 26 dB over 35 nm bandwidth in the targeted O-band region centered at 1310 nm. This fiber showed also an unsaturable loss of about 14% at 1195 nm pumping wavelength. This lower value, compared to the literature, was linked to the obtained high amplification performances. Besides, time-resolved photoluminescence measurements were performed. The dependence of emission lifetime on wavelength was associated to the existence of different Bismuth active centers.
Dedeyan et al. (Sun,) studied this question.