Research Of Microwave Frequency Comb Technology Based On Cascaded MZM Modulator

Microwave frequency comb(MFC)is composed of a series of discrete microwave signals with equal spacing of frequency components,which can simultaneously provide several microwave signals of different frequencies in a continuous frequency bandwidth range.It not only has the characteristics of microwave signal like light,penetration,non-ionality and information,but also has more spectral lines,wider frequency band width and higher spectral line spacing precision.At present,the methods of producing MFC at home and abroad are mainly divided into two categories: electrical and optical.The MFC based on optical mode can break through the bottleneck of electronic bandwidth.Compared with the MFC obtained by electrical mode,it has the advantages of wide bandwidth,high power and high load-to-noise ratio.Therefore,the generation of microwave frequency comb based on optical method is one of the hot topics studied by experts at home and abroad.Two schemes about how to produce high performance microwave frequency comb is proposed in this paper and the specific work is as follows:A scheme for generating a tunable MFC based on a cascaded Mach-Zehnder modulator(MZM)is proposed.The theoretical model is established,and the influence of the parameters such as light source wavelength,light source power,light source line width,small signal gain of bait-doped fiber amplifier(EDFA)and frequency of radio frequency modulation signal(RF)on the performance of output MFC is studied by using optical communication system design software VPItransmission Maker.The results show that by reasonably adjusting the parameters of the light source,RF and other components can make the generated MFC have a power of-11.10 d Bm,a signal-to-noise ratio of 57.04 d B,a flatness of 0.3d B and the MFC spacing can be tuned within 2-4GHz.A scheme for generating high-performance MFC based on cascaded MZM optical circuits is proposed.The theoretical model is established,and the influence of light source power,light source line width and RF frequency on the performance of output MFC is studied by using optical communication system design software Optisystem.The results show that by reasonably adjusting the parameters of the light source,RF and other components can make the generated MFC have a power of 23 d Bm,a signal-to-noise ratio of 61.13 d B,a flatness of 0.12 d B,a spectral bandwidth of 300 GHz and the MFC spacing can be tuned within 10-40 GHz.