Lumped Raman Fiber Amplifiers Based On Highly Non-Linear Photonic Crystal Fiber

A lumped Raman amplifier for all-Raman long-haul and ultra-long haul optical communications systems based on highly non-linear Photonic Crystal Fiber (HNL-PCF) is proposed and demonstrated. Applications for such an amplifier are discussed, focusing on discrete loss compensation for L-Band all-Raman reconfigurable systems. The main specifications required for this and similar applications have been analyzed, and include Power Conversion Efficiency above 30%, Net gain of about 15dB, and output power in the range of 20-23 dBm. Additional specifications such as Noise Figure, Multi-Path Interference (MPI), and transient suppression are also considered. In order to achieve the required specifications, the HNL-PCF should exhibit high Raman efficiency and low attenuation at pump wavelengths of 1470-1500nm, resulting in a Figure of Merit (FOM) above 8 dB(-1)W(-1). The splice loss of the HNL-PCF to conventional Single Mode Fiber is also shown to be critical, and should not exceed 0.5 dB. Initial samples of HNL-PCF have been characterized, and it has been demonstrated that high Raman efficiency and. low splice loss are achievable, while further work is being carried out to increase the FOM. Finally, an experimental demonstration of 10Gb/s WDM transmission using a prototype Lumped Raman Fiber Amplifier based on HNL-PCF is presented.