Study On Time Interleaved Photonic Sampling And Filtering Characteristics

Photonic analog-to-digital converter technique,which combines the photonics and traditional electrical analog-to-digital converter technique,has provide a key solution for the development of digital signal processing with high speed and broad bandwidth.It makes full use of the advantages of photonics,and has powerful strength in processing the broadband signal,long distance and anti-interference transmission.As an emerging discipline,microwave photonics studies the interaction of microwave signals and optical signals,which also provides the solution for the development of optical communication technique towards microwave frequency.The application of microwave photonic filters not only has the advantages(low loss,high bandwidth,resistance of electromagnetic interference,etc.)of the microwave signal processing based on the optical device,but also has the ability for reconfiguration and it is tunable.This thesis proposes a time interleaved optical sampling and digital filtering system.The system is based on the time interleaved photonic analog-to-digital converter structure.By adjusting the waveform of the optical sampling pulse train in time domain,the controllable system frequency response is realized,and thus the microwave photonic sampling and filtering can be achieved.This thesis carried out further research to verify the system both theoretically and experimentally.Firstly,this thesis introduces the principle and architecture of the time interleaved photonic sampling and filtering system.Theoretical model of the system is established and its working principle is illustrated through demonstrating the working process.Simulations have been carried out to validate the principle of this scheme.At the same time,some factors,such as the characters of optical pulse(pulse duration and the repetition rate)and bandwidth of the back end electronic processing module,which influence the system frequency response have been analyzed,thus provide the basis for design and optimization of different kinds of digital filters.Then,this thesis proposes a time interleaved optical sampling and filtering system based on OTDM.Through the OTDM multiplication module to control the time delay of optical pulse and produce the pulse train.Based on the power adjustment,the amplitude sequence of the pulse train is mapping by the tap coefficients of the designed digital filter,so the optical sampling and filtering can be realized at the same time.Experiment has established a system based on 16-channel OTDM.Through adjusting the waveform of the optical pulse train,digital filtering of equal-ripples,rectangular,and Blackman have been demonstrated,in addition with the equiripple filters with different pass and stop band character.Experiments verify the feasibility of photonic filtering to achieve different system response via controlling the waveform of optical pulse train in time domain.Finally,a time wavelength interleaved photonic analog-to-digital conversion system with 128GS/s sampling rate is set up,and full details in construction and test results are given.This system achieves a 512 times frequency multiplication to 250 MHz repetition rate pulses from mode locked laser through cascading a 32 times OTDM and a 16 channels WDM,which realizes the time wavelength interleaved photonic analog-to-digital converter system with 128GS/s sampling rate.