基于自参考源的高精度时间抖动测量

Timing jitter is a key parameter of low-noise systems, including optical frequency combs and low-noise laser microwave photon radar systems. Consequently, precisely measuring its values is quite important. The traditional direct detection method is limited by the floor noise of the microwave oscillator or photodetector noise, and its measurement accuracy is relatively low. Optical measuring methods, such as optical heterodyne and optical cross-correlation methods, are very complicated and have relatively high requirements on both reference and measured sources. This study presents a method to measure timing jitter with high precision without using a reference source, thereby overcoming some deficiencies of traditional methods. Based on long fiber delay line technology and optical carrier frequency interference, an attempt is made to realize ultra-high precision for measuring timing jitter. Results from the simulated system show that the noise base of a 10-MHz laser is 3.29×10 -13 fs2/Hz (equivalent to -211 dBc/Hz) when the frequency deviation is 100 MHz at its 100th power harmonic point 10 GHz, and the total root mean square timing jitter from 10 kHz to 10 MHz is 535 as, which has an obvious advantage for ultra-low timing jitter measurement. This measurement method is a convenient, high-efficiency method that can be applied to different measured sources, such as passively mode-locked lasers, optical frequency combs, and super-continuum spectra.