Composite broad-band fiber Raman amplifiers using incoherent pumping

Area of Science:

• Optoelectronics and Photonics
• Fiber Optic Communications
• Nonlinear Optics

Background:

• Conventional fiber Raman amplifiers often employ coherent pumping, which can lead to suboptimal gain flatness and noise performance over wide bandwidths.
• Composite fiber Raman amplifiers combine distributed and discrete amplifier stages to improve performance.
• Achieving simultaneous flatness in gain, noise figure, and optical signal-to-noise ratio (OSNR) is crucial for high-capacity optical networks.

Purpose of the Study:

• To investigate the performance of composite fiber Raman amplifiers utilizing incoherent pumping.
• To compare the effectiveness of incoherent pumping against conventional coherent pumping in terms of gain, noise figure, and OSNR flatness.
• To explore the impact of pump configuration (counter, co, bi-directional) on amplifier performance.

Main Methods:

• Experimental investigation of composite fiber Raman amplifiers.
• Comparison of amplifier performance using different pumping schemes: counter-incoherent, co-incoherent, and counter-coherent pumps.
• Analysis of gain, noise figure, and OSNR over a 100-nm bandwidth.

Main Results:

• Using two counter-incoherent pumps achieved flatter gain, noise figure, and OSNR over 100-nm bandwidth compared to six counter-coherent pumps.
• Bi-directional incoherent pumping further improved gain, noise figure, and OSNR flatness in composite fiber Raman amplifiers.
• A 1-dB ripple in gain and OSNR flatness was predicted using a combination of one co-incoherent and one counter-incoherent pump.

Conclusions:

• Incoherent pumping is a viable and advantageous alternative to coherent pumping for composite fiber Raman amplifiers.
• Optimized incoherent pumping configurations, particularly bi-directional setups, significantly enhance amplifier performance metrics.
• The findings suggest a pathway towards more efficient and spectrally flat fiber optic amplification systems.