Research On Optical Frequency Comb Generation Based On The Optoelectronic Oscillator

Optical frequency comb(OFC)is a special kind of laser source,whose spectrum is characterized by a series of equally spaced optical frequencies.Considering the characteristic of its spectrum,OFC has a wide range of applications in the fields of DWDM,high-precision measurement,spectroscopy and high-precision frequency standard.The main goal of the researchers currently is how to generate OFC with high flatness,high side-mode suppression ratio(SMSR),wide spectrum,high-stability and more spectral lines.And the optoelectronic oscillator(OEO)can generate the millimeter-wave radio frequency(RF)signal with high spectral purity,low phase noise and high RF stability.Therefore,this paper carried out a series of research on the generation of OFC based on the OEO.The main work is as follows:(1)The research background and significance of OFC generation technology are summarized,the research status of OFC generation and OEO techniques at home and abroad is reviewed.The structure and basic principle of OEO are studied.After this,the suppression effect of the double-loop structure on the side mode is analyzed,and the side mode suppression ratio of the microwave signal is improved.(2)The OFC generation technology is systematically summarized.The scheme of generating OFC based on single polarization/polarization multiplexing dual-parallel Mach-Zehnder modulator is studied.The results show that,by controlling the parameters of the modulator,the OFC with high flatness and high side-mode suppression ratio can be generated.(3)A new scheme of OFC generation based on the OEO is designed by using the polarization multiplexing dual-parallel Mach-Zehnder modulator.In which the deflection of one optical branch polarization state causes the two optical signals to be in a mutually orthogonal polarization state,and no interference occurs when the two waves are combined.At the same time,a high spectral purity microwave signal is generated by the OEO,and this microwave signal is used as the RF source of the modulator.As a result,an OFC with high flatness and high side mode suppression ratio is generated.And the reconfigurable OFC with tunable frequency spacing,tunable spectral line number and tunable center frequency can be obtained by flexible control of the center frequency of RF filter,the parameters of the modulator and the wavelength of the light source.