Optical Beat Signal Compression By Dispersion Decreasing Fiber And Fiber Loop Mirror Consisting Of It

In optical fiber communications, ultra-short optical pulse generation are always the research focus. A variety of pulse compression technologies and compressed pulses with high quality have been developed. However, the speed rate of optical fiber communication is not only determined by the pulse width, but also by the pulse repetition rate. Due to the high repetition rate of the beat signal, the compression of the signal becomes a hot research topic and is widely studied.This paper introduces the main pulse compression techniques and their respective characteristics. Then the simulation method and simulation of pulse compression are studied. Finally, the compression of beat signal by dispersion decreasing fiber and fiber loop mirror consisting of it are studied in detail. Particular works include the following three parts.(1) Introduce the step Fourier transform method with fixed step detailedly. According to the evolution of soliton in linear dispersion decreasing fiber, combined with split-step Fourier transform method, we proposed adaptive step split-step Fourier transform method, and give the adaptive step principle in simulating of soliton compression in linear dispersion decreasing fiber. Compared with the fixed split-step Fourier transform method, adaptive step split-step Fourier transform method introduce smaller error. Numerical simulation results of the two Fourier transform method show that the adaptive step split-step Fourier transform method can improve the simulation efficiency.(2) The design of dispersion decreasing fiber (DDF) for compressing stationary rescaled pulse is demonstrated in this paper. The dispersion profile of DDF is found to be decreased linearly. The compression ratio and power ratio are both equal to the ratio of initial and final value of second order dispersion coefficient for stationary rescaled pulse (SRP). When the dispersion slope of the fiber is small enough, the fundamental soliton without chirp can be approximated as SRP. When the dispersion slope of the fiber is high, the fundamental soliton without chirp has large difference with SRP. When the incident pulse is fundamental soliton with linear chirp, which is proportional to the dispersion slope of the fiber, the compression ratio and power ratio are closer to the ratio of initial and final dispersion value, which indicate fundamental soliton with linear chirp is approximated as SRP with less error than fundamental soliton without chirp.(3) Study of pulse compression of beat signal by linear dispersion decreasing fiber and fiber loop mirror based on linear dispersion decreasing fiber are demonstrated respectivlly. It is found pulse compressed by fiber loop mirror based on linear dispersion decreasing fiber have smaller sidelobe, and its spectrum have no obviously change, which indicate that it is more suitable for long-distance transmission.