A versatile analytic phase noise model for optical frequency-modulated continuous-wave interferometry

Frequency noise of frequency-swept laser fundamentally governs the performance of optical frequency-modulated continuous-wave (OFMCW) interferometry based technologies. Here, we proposed general and versatile analytic model capable of throughout analyzing and accurately predicting the performance of OFMCW system for lasers without assuming specific analytical forms of frequency noise spectrum (FNS). Compared to conventional noise models that rely on specific analytical expression or empirical parameter fitting, this approach establishes a direct link between the laser FNS and the performance of OFMCW system. It allows for highly accurate prediction of the beat note spectrum regardless of laser FNS characteristics with a computational complexity of O(NlogN), and thus enables assessing the impact of laser FNS on key performance metrics such as carrier-to-noise ratio, effective distance, and spatial resolution. Both theoretical and experimental demonstrations for laser with irregular FNS by incorporating optical phase-locked loop (OPLL) have validated an excellent agreement between the predictions and actual measurements with an average R-square of 0.9910. For a practical usage, the analysis permitted by this model reveals the dominance of low-frequency noise, confirming the important role of OPLL in improving the performance. With the verified accuracy, versatility, efficiency, and reliability, the proposed model provides a comprehensive and practical tool for design, characterization, and optimization of OFMCW systems.