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基于循环频移器(RFS)载波产生原理,创新性地提出了一种在循环频移环路中插入一个非对称马赫曾德尔干涉仪(AMZI),通过抑制噪声来提高信噪比的多载波产生改进方案。理论推导出光信号功率和放大自发辐射(ASE)噪声功率通过非对称马赫曾德尔干涉仪后的表达式。根据假设,在干涉仪两臂的光程差远远大于ASE噪声的相干长度,同时远远小于光信号相干长度的条件下,ASE噪声功率降低了3dB,而光信号功率没有改变。同时通过仿真和实验分别得到了50个子载波的输出。结果表明,基于该改进方案产生的多载波的载噪比可以达到37.5dB,比传统结构最多提高了17.5dB。
Based on the theory of carrier frequency generation in cyclic frequency shift (RFS) carrier, an innovative method of inserting an asymmetric Mach-Zehnder interferometer (AMZI) in a cyclostationary frequency-shift loop to improve the signal-to-noise ratio Produce improvement program. The theory deduces the optical signal power and the amplified spontaneous emission (ASE) noise power through the asymmetric Mach-Zehnder interferometer. According to the hypothesis, the ASE noise power is reduced by 3 dB while the optical signal power is not changed when the optical path difference between two arms of the interferometer is far greater than the coherence length of ASE noise and much smaller than the coherence length of optical signals. At the same time, the output of 50 subcarriers were obtained through simulation and experiment respectively. The results show that the carrier-to-noise ratio of multi-carrier based on the improved scheme can reach 37.5dB, which is up to 17.5dB higher than the traditional structure.