Time delay interferometry using laser frequency comb as the direct signal source. (April 2022)

• Record Type: Journal Article
• Authors: Wu, Hanzhong; Wang, Panpan; Hao, Peng; Du, Yuanbo; Tan, Yujie; Zhang, Jie; Lu, Zehuang; Shao, Chenggang
• Is Part Of: Optics and lasers in engineering. Volume 151(2022)
• Publication Date: 2022-04
• Subjects: Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2021.106938
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: We use the laser frequency comb to perform time delay interferometry with large time delay. The laser phase noise and the clock noise can be synchronized by using frequency comb as the bridge. The noise introduced by the downconversion network is below 10−6 Hz/Hz1/2 in the interested band. The laser phase noise and the clock noise can be reduced by 10 orders of magnitude and 5 orders of magnitude, respectively, by a single step of TDI. The space-borne frequency combs have been reported, and we suggest that the micro combs can be the qualified candidates for the future space mission of time delay interferometry. Abstract: In the ground-based gravitational wave detector, the laser phase noise can be cancelled out by virtue of the equal-arm configuration in a large-scale Michelson interferometer. However, this is not the case for the space-based gravitational wave detector, because it is difficult to ensure that the two arms are always the same in the flying constellation. During the past two decades, the technique of time delay interferometry (TDI) has been investigated in great depth, both theoretically and experimentally, which is able to suppress the noises including the phase noise of the laser source, and the clock noise in the post processing. As a versatile tool, optical frequency combs have achieved huge success in a number of applications, and recently, the space-borne laser frequency combs have been reported. In this work, we experimentally demonstrate that, laser frequency combs can directly serve as the signal source to perform time delay interferometry, while the side-band modulation is not required. The time base can be flexibly linked to the repetition frequency, and further synchronized to a single line of the frequency comb. The laser phase noise and the clock noise can be reduced by 10 orders of magnitude and 5 orders of magnitude, respectively, by a single step of TDI. The residual noise can be below 10 −4 Hz/Hz 1/2 in the interested band, and a weak signal with 0.1 μHz amplitude can be clearly observed. With further power stabilization and vibration isolation, the reduction performance can satisfy the requirements of LISA, TaiJi and TianQin.