Channel wavelength selectable single/dual-wavelength erbium-doped fiber ring laser

Abstract

We present a new channel wavelength selectable single/ dual-wavelength erbium-doped fiber ring laser. The novelty of this device is the use of a specially designed fiber cascaded Mach-Zender interferometer (MZI) called a channel wavelength generator (CWG) that has a triangular-shaped transfer function. The lasing wavelength only occurs in the vicinity of the peak wavelengths of the transfer function of the MZI when tuning the filter, and this makes it channel wavelength selectable. With a compound cavity structure, gain balance between two different wavelengths is easily achieved by adjusting the overlapping positions of the passbands of the filters over the CWG pattern, and as a result two stable lasing wavelengths are achieved simultaneous. Each wavelength can be tuned individually. The deviation of the exact lasing wavelength from the desired channel wavelength is estimated to be less than 1/20 of the CWG's channel spacing (100 GHz). In addition, it is also observed that the use of the CWG reduces significantly the number of longitudinal modes, and hence improves the stability of the output power.