Influence of Modulation Frequency Stabilization on Spectral Noise of Electromagnetically Induced Transparency

The conversion of the modulation signal from the coupling light to the probe light and the conversion of the additional phase noise from the coupling light to the amplitude noise of the probe light in the electromagnetically induced transparency (EIT) spectrum of the cesium atomic ladder type three level system were investigated by detecting the probe light output noise spectrum. It was demonstrated that frequency stabilization via external modulation can effectively avoid the transfer of modulation noise. In the experiment, two frequency stabilization methods external modulation transfer spectroscopy and internal modulation transfer spectroscopy were employed to achieve the frequency stabilization of the coupling light. The probe light noise spectra at the frequency stabilized output terminal and the detection output terminal were measured under both methods.