Intrinsic error vector magnitude on pulsed local oscillator coherent optical receiver measurements

Using a quantum optical noise description, we derive the fundamental noise limitation in the simultaneous measurements of the two quadrature of a signal performed by a double balanced pulsed local oscillator coherent receiver. The best achievable quantum limited signal-to-noise ratio and error vector measurement are derived. The general results are discussed more in detail for the equivalent time under sampling of optical communication signal with different modulation constellations. Results may be extended to real time signal sampling.