Noise transfer in cascaded nonlinear frequency conversion of single-frequency lasers

We present an analytical and experimental investigation of the noise transfer in single-frequency laser systems employing direct and cascaded nonlinear frequency conversion. Specifically, we compare the relative intensity noise (RIN) and frequency noise of light generated via direct sum-frequency generation (SFG) and via a cascaded conversion scheme in which second-harmonic generation (SHG) precedes SFG. The analysis introduces a theoretical framework for noise transfer in cascaded nonlinear frequency conversion that explicitly accounts for correlated pump fields and is validated by systematic measurements of the intensity and frequency noise of all lasers involved.