Half-open-cavity multiwavelength Brillouin-erbium random fiber laser with improved performance

Half-open-cavity multiwavelength Brillouin-erbium random fiber lasers (RFLs) with improved performance in terms of the generated Stokes order number and wavelength tuning range have been proposed and demonstrated. Our contrastive experiments reveal that the position of the used erbium-doped fiber (EDF) gain is crucial for the performance improvement of the Brillouin-erbium RFLs with half-open-cavity configuration. When the EDF is incorporated in the double-pass port of the circulator used, eighteen Stokes orders have been generated, which demonstrates the highest order obtained from Brillouin-erbium RFLs to the best of our knowledge. The Brillouin order enhancement is attributed to the sufficient gain for the randomly reflected Stokes wavelengths with the double-pass amplification. The broadest wavelength tunability of 54 nm is achieved in the case with the EDF located at the port 1 of the circulator, owing to its strongest suppression ability for self-lasing cavity modes. The significant performance upgrade that is obtained with these RFLs, whilst maintaining a simple structure, gives rise to promising potential applications in optical communications, microwave photonics, precision metrology and fiber-optic sensing.