Optimal signal-to-noise in digital phase lock amplifiers

We derive an expression for the optimal signal-to-noise ratio for linear phase lock amplifiers. In its digital form the optimal method can be implemented by real-time signal processing techniques. We analyze in detail the case of detector-noise-limited systems finding that the optimal technique can be used to eliminate effectively the detector's time constant from the set of parameters determining the overall efficiency. This has important implications for optical detection system design. We also report an experimental verification of the optimal method, thus establishing its practicality.