Research On The Generation Of Optical Frequency Comb Based On External Modulators And Its Application In Channelised Reception

As a multi-carrier light source with equal frequency spacing and approximately equal power,the optical frequency comb can be widely used in the fields of channelised reception and wavelength division multiplexing,and has attracted the attention of various research teams at home and abroad in recent years.Based on the generation of a large number of optical frequency combs,how to improve the flatness and side-mode suppression ratio of the optical frequency combs,while reducing the power of the RF signal has become the focus and difficulty of the research.In this paper,related research is carried out on the technical route of generating optical frequency combs by the external modulator method,and two different optical frequency comb generation schemes are proposed.Then,two instantaneous frequency measurement methods based on optical frequency comb have been designed for the application of optical frequency comb in channelized reception.The main work is summarised as follows.1.To improve the existing scheme for the problems of uneven number and flatness of optical combs,firstly,the optical frequency comb generation scheme of DPMZM cascaded dual parallel PolM is proposed,and result shows that the scheme can generate 66-line optical combs with the flatness of 0.73 dB.Based on this,the DPMZM cascaded FM,EAM and PolM optical comb generation scheme is proposed,and result shows that the scheme can ultimately generate 96-,150-,198-and 402-line optical combs with flatnesses of 2.32 dB,2.54 dB,2.96 dB and 3.98 dB.Both proposed schemes generate optical frequency combs with a high number of combs and good flatness,providing high quality coherent light sources for channelised reception,wavelength division multiplexing,etc;2.The application of optical frequency combs in channelised reception is investigated.Firstly,a channelized receive instantaneous frequency measurement and multi-band frequency conversion system is designed and result shows that the solution can achieve instantaneous frequency measurement of microwave signals from 0 to 29 GHz,and can also achieve multi-band frequency conversion of microwave signals.Based on this improvement,another improved channelized receive instantaneous frequency measurement scheme is designed and result shows that the scheme increases the number of channels and can realize the instantaneous frequency measurement of multi-frequency microwave signals from 0 to 270 GHz.Both schemes have a measurement error range of 0-0.1 GHz and have potential applications in future microwave photonic radar instantaneous frequency measurement systems.