Stable and widely tunable single-/dual-wavelength erbium-doped fiber laser by cascading a twin-core photonic crystal fiber based filter with Mach-Zehnder interferometer

A stable and widely tunable single-/dual-wavelength erbium-doped fiber laser (EDFL) is proposed by cascading a homemade twin-core photonic crystal fiber (TCPCF) based filter with Mach-Zehnder interferometer (MZI). By bending the TCPCF, single-wavelength lasing can be tuned from 1560.4 nm to 1583.44 nm with the tuning step of ∼0.78 nm and the widely tunable wavelength range over 23.04 nm can be achieved. Furthermore, by adjusting polarization controller, the output lasing can be switched from single-wavelength to dual-wavelength; the dual-wavelength lasing with wavelength interval of 0.78 nm can be tuned over a range of 33.82 nm from 1559.72 nm/1560.48 nm to 1593.54 nm/1594.32 nm. The tuning step and the interval of dual-wavelength is determined by the MZI. The SMSR of single- and dual-wavelength are higher than 45 dB and 42 dB, respectively. In addition, the stability of output lasing is measured experimentally. Excremental results demonstrate that the wavelength drift is less than 0.02 nm and peak power fluctuations of single-/dual-wavelengths are less than 0.47 dB and 0.8 dB, respectively. Such wide tuning range, small wavelength drift and high power stability makes this tunable EDFL have a potential application in the fields of optical fiber communication and sensing.