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

Ling Zhang,Yi Dong,Yuxiang Feng,Yinxia Meng,Zhangweiyi Liu,Wei Wei,Yuanshuo Bai,Haijun Zhou,Weilin Xie

doi:10.1109/jphot.2020.2997248

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.

Highlights

Coherent laser interferometry in the form of delayed self-interferometry (DSI) is one of the most important fundamentals in a wide range of laser-based communication, measurement, and signal processing systems such as coherent optical communication [1], [2], coherent metrology [3]–[5], optical sensing [6]–[8], coherent optical interferometry and reflectometry [9], [10], and so on
We present a compact and efficient approach, Fourier and inverse Fourier transform (FIFT) model, to precisely anticipate the performance limit caused by the laser frequency noise of any DSI system
Numerical and experimental comparisons prove the advantages of the FIFT model as follows: 1) The FIFT model is capable of evaluating the DSI system performance influenced by arbitrary laser frequency noise characteristics

Summary

Introduction

Coherent laser interferometry in the form of delayed self-interferometry (DSI) is one of the most important fundamentals in a wide range of laser-based communication, measurement, and signal processing systems such as coherent optical communication [1], [2], coherent metrology [3]–[5], optical sensing [6]–[8], coherent optical interferometry and reflectometry [9], [10], and so on. Formulas of the beat signal autocorrelation function (ACF) and DSI spectrum have been presented In this approach, laser linewidth is modeled to account for the contribution only from the white frequency noise. The coefficients are obtained by the proper fitting of FNS This way, the whole DSI spectrum can be constructed with the convolution of the spectra arising from these analytically-resolved noise components. Without fitting or any approximation, the proposed model offers an accurate prediction for the DSI spectra at different interferometric conditions based on arbitrary laser frequency noise properties.

FIFT Model Description

Numerical Verification

Experimental Setup

Model Comparison

Free-Running Laser With Irregular FNS

Phase-Locked Laser

Application

Conclusions