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光子时间拉伸模数转换(PTS-ADC)系统利用光纤中的色散效应对被采样模拟信号进行时间拉伸和带宽压缩,可大幅提高电模数转换器(ADC)的采样率和带宽。现有的PTS-ADC系统需要很长的色散光纤作为传输介质,它所带来的损耗限制了系统信噪比(SNR)和有效比特位(ENOB)。虽可通过提高光脉冲功率来改善系统的SNR,但色散光纤中的非线性效应利用了信噪比的提升。从理论推导、数值仿真和实验验证三个方面综合分析了非线性效应对PTS-ADC系统性能的影响,包括系统功率传输函数、载波与谐波功率比(CIR)。结果表明:第一段色散光纤中的非线性效应不会使得被采样模拟信号失真,相反地会提高系统带宽和CIR;而第二段色散光纤中的非线性效应则会恶化系统性能,应予以避免。
The Photonic Time-Stretched Analog-to-Digital Converter (PTS-ADC) system utilizes the dispersion effect in optical fibers to time-stretch and bandwidth-compress the sampled analog signal, dramatically improving the sampling rate and bandwidth of an electrical analog-to-digital converter (ADC) Existing PTS-ADC systems require a very long dispersion fiber as the transmission medium, and the resulting loss limits the system SNR and ENOB. Although the SNR of the system can be improved by increasing the optical pulse power, the nonlinear effect in the dispersion fiber takes advantage of the improved signal-to-noise ratio. The effects of nonlinear effects on PTS-ADC system performance are analyzed from three aspects: theoretical derivation, numerical simulation and experimental verification. The system power transfer function, carrier-to-harmonic power ratio (CIR) are systematically analyzed. The results show that the non-linear effect in the first dispersion fiber will not distort the sampled analog signal, but will increase the system bandwidth and CIR. On the other hand, the nonlinear effect in the second dispersion fiber will deteriorate the system performance. avoid.