We describe frequency noise measurements for an optical frequency comb by using a delayed self-heterodyne method with a Michelson-type fiber-optic delay line interferometer without a low-noise reference laser. We measured the frequency noise power spectral densities (PSDs) for free-running and frequency-stabilized comb modes and estimated the uncertainties of the measurement results. For example, for the frequency-stabilized comb, the measured frequency noise PSD and its uncertainty were 23 dBHz 2 Hz −2 and 0.66 dB, respectively, at a Fourier frequency of 10 kHz. We also measured the frequency noise PSDs of the comb modes by the conventional method using an ultrastable reference laser and compared the results with those that we measured with the delayed self-heterodyne method. The measurement results that we obtained with the two methods were consistent within their uncertainties, which shows that the delayed self-heterodyne method provides high reliability. ...

中文翻译：

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使用延迟线干涉仪的光学频率梳的频率噪声测量及其不确定度估计

我们通过使用具有低噪声参考激光器的迈克尔逊型光纤延迟线干涉仪的延迟自外差方法描述了光学频率梳的频率噪声测量。我们测量了自由运行和频率稳定的梳状模式的频率噪声功率谱密度（PSD），并估计了测量结果的不确定性。例如，对于频率稳定的梳，在傅立叶频率为10 kHz时，测得的频率噪声PSD及其不确定度分别为23 dBHz 2 Hz -2和0.66 dB。我们还使用超稳定参考激光器通过常规方法测量了梳齿模式的频率噪声PSD，并将结果与​​采用延迟自外差法测量的结果进行了比较。我们用这两种方法获得的测量结果在其不确定性上是一致的，这表明延迟自外差法具有很高的可靠性。...