Fourier and Inverse Fourier Transform Model for Delayed Self-interferometry System

Abstract

Understanding the effects of laser phase and frequency noise on laser interferometry is significant for evaluating the system performance. To precisely study the performance limit caused by laser frequency noise, here we propose and demonstrate a versatile model based on the Fourier and inverse Fourier transform (FIFT) method. This model, capable of estimating the beat note spectra of different delayed self-interferometry (DSI) with laser sources of arbitrary frequency noise properties, allows for accurate evaluations of the noise performance in a variety of interferometry based systems. Such a model has been experimentally validated using lasers with irregular frequency noise properties such as cavity stabilized fiber laser or laser under optical phase-locking, providing more detailed insight into the evolution of the frequency noise dynamics at different interferometric conditions. With average estimation goodness (AEG) of 0.9716 and computation complexity of O(NlogN), this model offers greater accuracy and lower complexity than conventional methods. It has also been confirmed that this model permits to distinguish the contributions from the laser frequency stability and other noise sources, which could be helpful for the noise analysis and performance optimization of the system.

Noise analysis in coherent phase demodulated analog photonics transmission link under different power levels

“…Considering a fiber laser, there simultaneously exist flicker frequency noise (1/f noise) and white frequency noise. As a result, the total phase noise of a fiber laser can be given by their weighted combination [9] as,…”

Optimizing of laser source parameters for FMCW automotive LiDARs

“…Because of the nonlinearity of a chirp rate in a time 𝐾(𝑡) = 𝐾 0 + 𝛥𝐾(𝑡), we can distinguish target chirp rate 𝐾 0 = 𝐵 𝑇 and the nonlinear part 𝛥𝐾(𝑡). Therefore, we could assume that the left term of a n argument represents linearization quality while the second term is a frequency noise part of the laser radiation and the phase difference 𝜑(𝑡) − 𝜑(𝑡 − 𝜏) could be estimated statistically by the beat note frequency noise spectrum (FNS) 𝑆 𝛥𝜈 (𝑓) 4,5 .…”

“…From here, the further operating by the linewidth loses its practical meaning. For a more accurate description of the contribution to the laser frequency stability, it is better to employ the spectral density of the laser frequency noise statistically, which will allow us to estimate the SNR and the probability of signal detection in any system at different distances 4 . It is useful to consider the example with a phase locking technique for the assessment of the detection performance.…”