How is laser clipping characterized on a spectrum analyzer?

Laser clipping on a spectrum analyzer is characterized by an elevated noise floor above a certain frequency after optical conversion, typically around 42 MHz. This phenomenon occurs because, during laser clipping, the signal experiences a distortion where peaks of the signal become flattened or "clipped." As a result, the harmonic and noise components increase, leading to a higher noise floor detectable on the spectrum analyzer.

In this context, the increase in the noise floor reflects not just random noise but also harmonics generated due to the clipping effect. This distinct change in the behavior of the noise floor allows for differentiation from other types of signals and anomalies in the system. Thus, identifying an elevated noise floor specifically after a certain threshold frequency is a key indicator of laser clipping, making this option accurate in characterizing the effect on a spectrum analyzer.