Generation And Optimization Of Sampling Light Pulsed In Wavelength Division Multiplexing / Time Division Multiplexing Optical Sampling System

Digital signal are more flexible and stable than analog signals. As a result, digital signal processing technique is widely used in various industries and fields. As the electronic and communication technologydevelop rapidly, it is of more significance for analog-digital converters (ADCs) to increasesample rate and precision. It is necessary to decrease the time jitter of chips to improve ADC’s performance. Pure electric analog-digital converter has been close to its theory limit because of bottleneck of electronics. So it is too difficult to further decrease time jitter. In the1970s, S. White et al. put forwardopticsanalog-digital conversion which has attracted extensive attention abroad since then. And the technology can solve the time jitter problem effectively.This article studies the light sampling system combining with wavelength division multiplexing and time division multiplexing technology, and focuses on some problems of affecting sampling system.Firstly, this article introduces the fundamentals and sampling process of the multi-wavelength systemrealizing128GSa/s, and constituent parts of the system.The128GSa/ssampling pulse sequence comes from pulseof low repetition frequency andbroadband spectrumthrough16-wavelength division multiplexing and then32-time division multiplexing. After that, we can get16-sampled signal after wavelength division demultiplexingby electrooptic modulatorand then parallel processing.Theoretical analysis and numerical modeling are conducted on the structural characteristics of time division multiplexing. Sampling pulse amplitude jitter and control delay may arisebecause of both the inconformity of insertion loss and the diversity ofpathsintime division multiplexingsystem.Precise opticalmodulator and attenuator are applied to control time delay and balanceamplitude jitter. In this study, two kinds of multiplexing structures, polarizationmodulation and self-polarization-maintaining,are designed to solve the chaotic polarization state.This article explains the principles of the two schemes, sets upsampling systems, tests sampling sinusoidal signals, and compares the two combining with the sampling results to analyze their advantages and disadvantages separately. At the end of the article, the process of the time division multiplexing is elaborated.A method of precise time delay is put forward for wavelength division multiplexing system whose time delay is too short to be measureddirectly. In this article, autocorrelator is applied. Standard comparisonoptical fiber is introduced as the baseline. The interval of autocorrelationpeak can reflect the delay time of each channel accurately.Dispersion will lead to time interval error while in this article the impact can be removed by setting additional delay in each channel of the system.