Abstract

Bismuth (Bi) doped fibers have shown a promising potential for lasers and amplifiers in the 1150-1500 nm wavelength region [1]. This spectral region can serve a wide range of applications, such as medicine, astronomy and optical telecommunications [1, 2]. However, Bi-doped fiber lasers and amplifiers are still far from their optimum performance owing to the unclear nature of the near-IR emitting Bi active centers. Bi-doped alumino-silicate (BAS) fibers which provide amplification in the 1150-1200 nm spectral region have been relatively less explored. To the best of our knowledge, up to now a maximum gain of about 5 dB has been reported at room temperature with a pump power of few watts at a wavelength of 1180nm [1, 3]. This is attributed to the fact that the unsaturable loss (UL) and exited state absorption (ESA) impairments make the realization of efficient amplifier a rather difficult task particularly in BAS fibers [2, 4]. ESA has been shown to appear at both pump and signal wavelengths and increases towards shorter wavelength side [4]. This makes the choice of pump wavelength critical. In this paper, for the first time, we demonstrate a BAS fiber amplifier pumped by a commercially available laser diode (LD) operating at 1120 nm. The gain in BAS fiber was compared at two pump wavelengths; 1047 nm (conventionally used) and 1120 nm. Pumping at 1120 nm wavelength provides higher gain as the above mentioned impairments are significantly reduced.

© 2015 IEEE