C-band wavelength tunable mode locked noise-like pulse source using an asymmetrically reflecting Fabry-Perot filter

Abstract

We report a widely wavelength tunable mode locked noise-like pulse (NLP) source from an erbium doped fiber ring laser. By making use of the reflection of an asymmetric Fabry- Perot interferometer (FPI), continuous tunability of the central wavelength over the entire C-band (1530 nm to 1565 nm), with an independent control over bandwidth (3.5 nm to 17 nm) is demonstrated. Using a single control parameter, i.e. the length of the FPI, it is thus possible to select from a range of output spectral bandwidths and desired central wavelengths. Using the same control on the length of the FPI and intracavity polarization settings, generation of dual wavelength NLPs, temporally shifted noise-like pulse pairs, harmonic mode locked NLPs and loosely bound NLP doublets and NLP triplets are reported. Owing to the simplicity of the tuning mechanism and the adaptable output spectrum, we believe, such a laser will be useful for various applications like sensing, spectroscopy and imaging. The novel combination of a reflecting FPI-based filter, and the complex nonlinear polarization rotation (NPR) based mode locking mechanism, also offers the opportunity to further explore the rich physics of NLPs.