Novel structure L-band erbium-doped fiber laser

A L-band erbium-doped fiber ring laser is demonstrated. The ring cavity is constituted by erbium-doped fiber (EDF) as the gain medium, a 980 nm laser diode as the co-pumping source, and a polarizer and a polarization controller as the L-band wavelength selective device. To be recycled, the backward amplified spontaneous emission (ASE) was routed to the input of EDF by an optical circulator. The lasing threshold is approximately 23.87 mW, the output laser power reaches 6.34 mW and the slope efficiency comes up to about 8.05% when pumping power is set to 103 mW. Compared with the laser without utilizing backward ASE, it is apparent that the performance of L-band fiber ring laser has been much improved. When inapposite length EDF was used, no laser output was obtained without utilizing backward ASE; whereas laser with the threshold power of about 88 mW has been achieved with backward ASE compensation. Thus the above conclusion is well proved.