Raman Amplification in Fiber Optical Communication Systems,

Introduction: Overview of an optical telecommunication system; What is an optical fiber'Stimulated Raman scattering (SRS) in optical fibers; Benefits of SRS; The emergence of Raman amplification. Stimulated Raman Scattering in optical Fibers: Maxwell’s and the wave equation; Fiber Modes; Nonlinear Schrödinger Equation; Raman gain process; Coupled Amplitude Equations; CW coupled equations. Raman Pumping in Optical Fiber Communications: Semiconductor Lasers; Laser structure; Materials used; Current capabilities e.g. power range, wavelength range; Future trends; Raman fiber lasers; Description of the cascaded Raman fiber laser process; Description of pump sources; 9xx multimode diodes; Yb-doped cladding pumped fiber laser; Rate Equations describing the process; Performance optimization e.g. choosing fiber length, output coupler reflectivity; Multiple wavelength pumps; Higher order pump sources; Current capabilities e.g. power range, wavelength range; Comparison between the two sources. Distributed Raman amplification along the Transmission span: Optical signal-to-noise ratio; Increasing the optical signal-to-noise ratio; Increasing span reach or capacity; Equivalent noise and how to measure it; Multiple wavelength Raman pumps for gain flatness; Selecting the correct wavelength and power distribution; Co and counter pumping; Advantages of counter pumping; Reasons for co-pumping; Higher-order pumping; Why use higher order pumping? The tradeoff between going to different orders; Time division multiplexing of pumps; Tradeoff between OSNR and nonlinear penalties. Discrete Raman amplifiers: Contrast with distributed amplifiers; Rayleigh backscattered light; Noise figure now dominated by amplified spontaneous emission; Comparison of discrete Raman amplifiers with other approaches, e.g. erbium, thulium etc.; Dispersion compensating fiber (DCF); What is DCF and why is it used; Raman properties of DCF fiber which makes it attractive; Amplifier design issues; Fiber lengths; Number of stages; Optimization of fibers for dispersion compensating Raman amplifiers. Impairments and Limitations to Raman Amplification: MPI penalties; Rayleigh backscattered light; Effect on system performance; Measurement techniques; Time Domain extinction method; Electrical spectrum analyzer method; Pump signal transfer; Transient effects such as adding or dropping channels in single spans and multiple spans; FWM impairments; Pump-pump interaction; Pump-signal interaction.