通路不对称对基于平衡探测的光模数转换系统性能的影响

Effect of Path Asymmetry on Performance of Optical Analog-to-Digital Conversion System Based on Balanced Detection

平衡探测器的两输入通路在增益和时延上的不对称会对基于平衡探测的光模数转换(PADC)系统的性能产生影响。建立了基于平衡探测的PADC系统的数学模型,理论上分析了系统有效比特位(ENOB)与平衡探测器两输入通路的增益和时延的不对称性,并仿真分析了增益和时延的不对称对系统ENOB的影响,同时进行了相应的实验验证。结果表明,在相同调制深度下,系统的ENOB随着两输入通路的相对增益和相对时延的增加而减小。当平衡探测器两输入通路在增益和时延上完全一致时,系统的ENOB随着调制深度的增加而逐渐减小;当平衡探测器两输入通路在增益和时延上存在偏差时,系统的ENOB随着调制深度的增加先增大后减小。

The asymmetry of gain and time delay in two input paths of the balanced detector will affect the performance of the optical analog-to-digital conversion （PADC） system based on balanced detection. A mathematical model of the PADC system based on balanced detection is built. The relationship between the effective number of bits （ENOB） of the system and the asymmetry of gain and time delay in two input paths of the balanced detector is given. The effect of asymmetry of gain and time delay on ENOB of the system is analyzed by simulation, and corresponding confirmatory experiments are carried out. The results show that ENOB of the system decreases with the increase of relative gain and relative time delay in two input paths under the same modulation depth. When the gain and the time delay in two input paths of the balanced detector are exactly the same, ENOB of the system decreases with the increase of modulation depth. When the gain and the time delay in two input paths of the balanced detector are different, ENOB of the system increases at first with the increase of modulation depth and then decreases.