Tunable dual-wavelength erbium-doped fiber laser stabilized by four-wave mixing in a 35-cm highly nonlinear bismuth-oxide fiber.

Using four-wave mixing in a 35-cm highly nonlinear bismuth-oxide fiber incorporated in an erbium-doped fiber laser, a stable dual-wavelength output is obtained. The spectral spacing has been tuned from 1.3 to 7.2 nm with a tunable fiber Bragg grating. Simultaneous tuning of the two wavelengths over 20 nm is also demonstrated using a tunable bandpass filter together with a birefringent filter defining a 100-GHz frequency comb. The output stability has been experimentally analyzed. An abrupt reduction in the intensity fluctuation is observed when the amplifier output power reaches 22.0 dBm. At 22.3 dBm, the fluctuation attains a lower limit of approximately 1 dB.