Operational characteristics of the optical fiber Raman amplifier was examined in terms of the stimulated Raman scattering theories, where the fiber Raman amplifier(FRA) due to the wide Raman bandwidth of the order of 10 THz was pointed out to be well suited for optical amplifier of the multichannel communication system and also for amplification of the picosecond range short pulses.
In the stimulated Raman scattering where both forward and backward pumping are simultaneously possible, the difference between the two was examined to show that there should be no annihilation of pumping power in the backward pumping.
Numerical analysis of the Raman OTDR, where both forward and backward pumpings are simultaneously present and the pumping laser is periodically incident at optical fiber through the wavelength dependent fiber coupler, shows that the malfunction of the repeater in either forward or backward pumping may be located.
Self-phase modulation spectral patterns are studies through numerical calculations in the optical fiber for input signals formed by a superposition of a pair of pulses of half-width greater than ∼,40 ps, when the group velocity dispersion effect on the self-phase modulation can be neglected. The self-phase-modulated output from the optical fiber is found to show distinctive spectral patterns of varying side lobes depending on the phase shifts between the input pulse pairs. A possible application of this observation as a new method of phase shift keying modulation is suggested.