Research On Key Technology Of Optoelectronic Analog-to-digital Conversion

Optoelectronic analog-to-digital conversion technology borns the advantages of photonic technology in high-speed and wideband signal processing,and uses optical technology instead of electrical sampling,which has the advantages of improving the sampling rate and bandwidth,and improve the performance of analog-to-digital conversion.This paper introduces the research status of optoelectronic analog-to-digital conversion technology at home and abroad,classifies the existing optoelectronic analogto-digital conversion structures,and analyzes the advantages and disadvantages of different structures.The optoelectronic analog-to-digital conversion technology based on optical delay is presented in this paper.Following are the content of this paper:Firstly,the optical sampling electroquantization analog-to-digital conversion scheme is adopted.The clock distribution module generates high speed electric pulse to modulate the direct beam signal to generate light pulse.The bandwidth of the modulator is up to40 GHz.After the light pulse passes through the shunt module,the optical fiber delay line is used to separate the light pulse in the time domain,and the analog signal is sampled by the optical modulation module.The optical pulse after sampling is broadened by optical fiber dispersion technique.After the broadened optical pulse is received and quantized by the electronic analog-to-digital converter through the optical detection module.Then the error of the system modules is discussed,which is based on the key technology of optical electric quantitative sampling system,The relationship between the amplitude consistency and the delay consistency and the significant number of the system is derived,and use Matlab to draw the simulation curve,quantitatively analyzes the amplitued-phase consistency under different signal frequency effect the efficient digits of the system.Finally,an eight-channel photoelectric analog-digital conversion experimental system is built.The low cost F-P wide spectrum light source is used to modulate high speed electric pulse to generate 12 GHz optical sampling pulse.The delay difference between adjacent channels is designed to be 83.3ps,so that the pulse is separated in the time domain.The delay precision of the whole optical sampling channel is controlled within 1ps to ensure the system has high delay consistency.Based on the experimental data,different amplitude errors are introduced and the variation trend of the effective number is discussed.The effect of delay error on effective bits is discussed at various signal frequencies.The experimental system combines the advantages of high sampling rate of optical sampling and high precision of electroquantization,the sampling rate reaches 12GS/s,the sampling process adopts a broadband modulator,and the system bandwidth reaches10 GHz.In the experiment,the signals within the range of 505 MHz to 1.5GHz were sampled,and the time domain sampling point diagram and spectrum diagram of the signals were obtained by data processing software.With the increase of signal frequency,the effective bits of the system decrease gradually,and the effective bits of low frequency and high frequency are 7.35bit@505MHz and 5.45bit@1.505 GHz.The DFB narrow linewidth laser was used to replace the F-P source to generate the sampled optical pulse,which eliminated the amplitude jitter at the top of the optical pulse.An optical pulse broadening method based on the narrow linewidth laser was proposed.The time-domain separation of the optical pulse was achieved by multi-channel delay reflection,and the optical pulse broadening was achieved by coupling the optical coupling module.