Research On Photonic Time-stretch Analog-to-Digital Conversion Technology Based On Dissipative Soliton

High-speed analog-to-digital converters(ADCs)have important applications in next-generation information systems such as radar sensing,medical imaging,and ultra-wideband communication systems.There are two main bottlenecks in the traditional electronic ADCs:time jitter and comparator ambiguity.In ADCs,using the optical technology can improve the effective sampling rate and the maximum input analog bandwidth of the system.In order to reduce the frequency and compress the analog bandwidth,the optical time-stretch structure is added before A/D conversion,which greatly reduces the influence of time jitter and comparator ambiguity on the accuracy of A/D conversion.However,there are three outstanding problems with the optical time-stretch A/D conversion system:power penalty by fiber dispersion,signal distortion caused by the optical pulse envelope,and harmonic distortion caused by the modulation.The performance of the optical time-stretch system can be improved greatly by using the dissipative soliton optical pulses,which have a high energy spectral density and a relatively flat spectrum with steep edges.Therefore,it is of great significance and application value to study the technology of time-stretch ADC based on dissipative soliton.In this thesis,an optical time-stretch scheme based on dissipative soliton is proposed.The main work is as follows:A dissipative soliton fiber laser with the large energy spectral density and the flat wide spectral characteristics is experimentally constructed,and it is used in the complementary dual-output optical time-stretch system,which can reduce the impact of the optical envelope on system performance.Combined with simple algorithms in the digital domain,even harmonics are eliminated and odd harmonics are weakened.An optical time-stretch ADC system with a 10-fold stretch factor,an effective sampling rate of 100 GS/s,and an effective number of bits of 4.4 bits was obtained through experiments.Moreover,in order to solve the problem of limited analog bandwidth of optical time-stretch system,a single-sideband(SSB)modulation system based on dissipative solitons was studied.In the simulation,the performance of the double-sideband(DSB)modulation system and the SSB modulation system is evaluated synthetically by the time-bandwidth product(TBP).Without using an optical amplifier,the experimentally constructed single-channel single-sideband modulation system achieved an effective number of 3.1 bits.In addition,other factors affecting the 3 dB bandwidth of the system were explored in the experiment.