Numerical analysis of field distribution on mixing efficiency

摘要

To make full use of the return signal, a frequency stable local oscillator is applied in coherent detection system. A detectable intermediate frequency signal is generated by mixing the two fields in a square law photodetector. The influence of fields distribution on mixing efficiency is discussed. To obtain higher mixing efficiency, the mixed fields need collimation, polarization alignment, and normal incidence. Numerical analysis shows that the mixing efficiency is more sensitive to the alignment of the incident signal than to the local oscillator field, and the detector radius must be larger than the beam waist size of the signal.