46$\,\times\,$2.5 GHz Mode-Locked Erbium-Doped Fiber Laser With 25-GHz Spacing

We demonstrate a mode-locked, multiwavelength erbium-doped fiber laser at 2.5 GHz with 25-GHz channel spacing and that is wavelength tunable from 1545 to 1558 nm. Stable, room-temperature operation is obtained by exploiting four-wave mixing in a length of highly nonlinear fiber. At a central wavelength of 1549.5 nm, we obtain 30 wavelengths within 3 dB and 46 wavelengths within 6 dB; the full-width at half-maximum of the envelope is 85 ps.