A novel intra-cavity for efficient cascaded Raman generation using WDM couplers

A novel intra-cavity with a broadband spectral response is designed and demonstrated to deliver a 4th order Stokes cascaded Raman generation. A large transmission bandwidth of 295 nm is realized using the two WDM couplers. The results applied to a Raman fiber laser operating at 1706 nm wavelength using a 1313 nm pump source are reported.

1. Introduction

Raman fiber laser and its applications as a pump source for distributed Raman amplifiers are currently experiencing renewed interest as a result of recent prospects of 40Gb/s WDM system implementations [1]. The introduction of resonant and cascaded. all-fiber geometries that utilize fused WDM couplers[2] or Bragg gratings[3] has enhanced conversion efficiencies and allows extended wavelength coverage in CW operation. To obtain a tunable wavelength 'operation of the Raman laser, WDM couplers which have comparatively broad bandwidth are preferred.