Tunable Fiber Laser Using an Er/Yb Codoped Fiber Based Modal Interferometer Filter

A tunable erbium-doped fiber laser (EDFL) is proposed and demonstrated experimentally. It is based on a tunable fiber filter using the pump induced refractive index change characteristics of the Er/Yb codoped phosphosilicate fiber (EYDF) based modal interferometer (MI). The laser achieves a tunability of 2.39 nm and 1.60 nm, with the wavelength linearly tuned from 1534.05 nm to 1536.44 nm and from 1554.36 nm to 1555.96 nm by changing the pump power injected into the MI. Its side mode suppression ratios are 30 dB and 33 dB, respectively. The stability of the tunable EDFL is getting better with the continuous improvement of the power of pump 1, and the dual-wavelength power fluctuations are less than 0.22 dB and 0.12 dB within 20 min at 250 mW of pump 1, respectively.