Compact Brillouin bismuth–gallium–aluminum co-doped erbium doped fiber laser

A single-wavelength Brillouin–erbium fiber laser (BEFL) is demonstrated using high germanium dopant concentration fiber and bismuth–gallium–aluminum co-doped high concentration erbium doped fiber (EDF). A 20-m long high Ge-doped fiber is used to provide nonlinear gains to generate a stimulated Brillouin scattering (SBS), and a 4.3-m long Bi–Ga–Al EDF provides linear gains to amplify the SBS. The relationship between the fiber parameters (dopant concentration, effective area, length and so on) of both linear and nonlinear medium and the output performance was discussed. The BEFL power increases as the effective area of the high Ge-doped fiber decreases. There is an optimum length in the high Ge-doped fiber which is 20-m long in this paper. The BEFL output power also increases as the output power of the Bi–Ga–Al EDF increases. The output performance increases as the erbium doping concentration increases. It is necessary to get the effective area of the Bi–Ga–Al EDF large enough to decrease the fiber loss. The optimum length in the Bi–Ga–Al EDF is 4.3 m. The BEFL operates at 1563.61 nm, which is upshifted by 0.09 nm from the Brillouin pump (BP). It has a peak power of −3 dBm and a side-mode suppression ratio of 26 dB. The BP wavelength is tunable within a wavelength range from 1562.5 to 1564 nm. The BEFL has a narrow linewidth. It is suitable for many potential applications, such as optical communication and sensors.

► We use only 20-m long fiber to provide the nonlinear gain. ► We use the bismuth–gallium–aluminum co-doped erbium doped fiber. ► The peak power is −3 dBm and the side-mode suppression ratio is more than 26 dB.