Ultra-long Distributed Second-order Raman Fiber Amplifier And Its Application In RoF

Nowadays,an increase of use of the distributed Raman amplifier in the optical fiber transmission system has occurred because of the development of the pump laser.In order to suppress the amplified spontaneous emission noise,the signal light should be transmitted evenly and ultra-long distributed second order Raman amplifier system is a reliable choice.This paper mainly has studied the ultra-long distributed second order Raman amplification system and its application on the radio-over-fiber.Firstly,we review the advantages of optical fiber Raman amplifier comparing to other amplifiers as well as the research progress of optical distributed fiber Raman amplifier and its applications at home and abroad,explain the basic concept of stimulated Raman scattering,Raman gain spectrum and Raman threshold,introduce the application of stimulated Raman scattering in optical fiber Raman lasers and distributed optical fiber sensors based on stimulated Raman scattering,and analyze the theoretical model of the cascaded Raman fiber laser.We expound the basic principle and structure of the ultra-long distributed second-order Raman amplification,and apply it in L-band.We prove that using the ultra-long distributed second-order Raman amplifier to amplify the L-band optical signal is feasible and advantageous by the simulation and experiment because the on-off gain of the amplifier can compensate for the loss of the optical link.Then,we analyze the factors which influence performance the radio-over-fiber transmission system,including the power of optical carrier,the radio frequency and the influence of fiber dispersion,and introduce the main performance parameters of radio-over-fiber transmission system,including the link gain and noise figure.We analyze the impact on radio frequency signal on-off gain in the transport process because of pump power,the frequency response of radio-over-fiber transmission system with the ultra-long distributed second-order Raman amplifier and the performance of the system on noise and phase noise.By experiment,we verify the relationship between the on-off gain of optical signal and the on-off gain of RF signal.We can conclude that the ultra-long distributed second-order Raman amplification does have an enhancement about 28.1dB on the radio-over-fiber transmission system and quasi-lossless transmission can be achieved on optical domain at distance of 81.0 km.The result of phase noise measurement proves that broadband signal transmission based on ultra-long distributed second-order Raman amplifier has some superiority in noise reductions over traditional low noise amplification in electrical domain.