Study On The Bandwidth Broadening Of Fiber Optical Parametic Amplifier

All fiber-optic transmission systems need optical amplifiers to compensate for fiber loss. Fiber optical parametric amplifier (FOPA) is a new kind of optical amplifier which relying on four-wave mixing (FWM) has received increased attention lately due to their potentials for applications as signal amplifiers, wavelength converters, and all-optical signal processors.Currently, FOPA can be designed with conventional dispersion shifted fiber (DSF) and highly nonlinear dispersion-shifted fiber (HNL-DSF). It has small amplified bandwidth when the FOPA is designed with DSF. In order to broaden its amplification bandwidth, a cascade configuration with periodic dispersion compensation composed of conventional DSF and single mode fiber (SMF) is used in this paper. Then the FOPA is studied as follows:Firstly, combining the four-wave-mixing coupling equations, the expression of output power, phase and gain of the signal and idler for the DSF+SMF dual pump FOPA are derived when considering the different boundary condition. Meanwhile, the phase-matching method which using the positive second-order dispersion of SMF to compensate the phase-mismatch caused by the negative fourth-order dispersion of DSF is presented. And the optimal SMF length is obtained. The amplified bandwidth designed by this length can be efficiently broadened.Secondly, using the four-wave-mixing power coupling equations, the DSF+SMF dual pump FOPA is simulated. The results show, for a fixed DSF length, consisting of two equal segments, and using the optimal SMF length to compensate the dispersion can efficiently broaden the amplification bandwidth. It further shows that a larger bandwidth can be obtained by using multi-segments compensation for the same DSF length. Other, longer DSF length, larger pump power can obtain larger bandwidth and gain. At the end, the theoretical and simulated properties are compared, and the compared result shows the validity of the derived expressions.