Quantum Limit Characterization of Signal-to-Noise Ratio using Phase- Shift Keying in Homodyne Detection


In this work, a mathematical treatment for the quantum limit of signal-to-noise ratio (SNR) in homodyne coherent detection was presented. This treatment is based on the case of balanced detection when the incident signal power is much lesser than the local oscillator power when the efficient AC coupling is assumed. The final results were obtained from an analytical expression of SNR dependent of the average number of incident photons and the quantum efficiency.