Abstract

Light traversing an optical fiber is subject to various local phase perturbations driven by temperature. This thermal phase sensitivity is undesirable in fiber interferometers and their applications which require that a fixed, stable phase be received after propagation. The use of hollow core fiber (HCF) has been shown to reduce this thermal phase sensitivity over solid core fibers and here we propose and demonstrate how coiling HCF to a prescribed geometry can further significantly reduce this sensitivity. Our proof-of-concept experiment shows reduction by a factor of ∼90 with respect to the uncoiled HCF, and over three orders of magnitude with respect to uncoiled solid core optical fiber. Our strategy exploits a nuance of the elastic properties of fiber coils whereby the constrained thermal expansion of the composite material (fiber + coating) can result in a coil having compressed inner layers and expanded outer layers. Thermal expansion is the dominant effect responsible for thermal phase sensitivity in HCFs, and in this scheme the compressed inner coil layers compensate the thermal expansion of the outer layers. In this study we design the coil parameters using finite element simulations, studying the relationship between coil performance and its key parameters. The proof-of-principle coil has 160 mm diameter and incorporates a 548 m length of HCF out of which a 230 m section shows almost zero (slightly negative) thermal phase sensitivity. Though the coil shows low thermal phase sensitivity over tens of hours, the long-time constant viscoelastic properties of the coating materials used in the HCF under study are shown to limit these benefits. To make this strategy practical for systems with fast temperature dynamics, a coating having more stable mechanical properties could be used. For precision timing systems in which long thermal time constants are already the norm, this scheme represents a low-cost and provides a significant reduction to thermal sensitivity which is immediately practicable.

Hollow-core fiber Fabry–Perot interferometers with reduced sensitivity to temperature

Meng Ding, Eric Numkam Fokoua, John R. Hayes, Hesham Sakr, Peter Horak, Francesco Poletti, David J. Richardson, and Radan Slavík
Opt. Lett. 47(10) 2510-2513 (2022)

Thinly coated hollow core fiber for improved thermal phase-stability performance

Bo Shi, Hesham Sakr, John Hayes, Xuhao Wei, Eric Numkam Fokoua, Meng Ding, Zitong Feng, Giuseppe Marra, Francesco Poletti, David J. Richardson, and Radan Slavík
Opt. Lett. 46(20) 5177-5180 (2021)

Demonstration of opposing thermal sensitivities in hollow-core fibers with open and sealed ends

R. Slavík, E. R. Numkam Fokoua, M. Bukshtab, Y. Chen, T. D. Bradley, S. R. Sandoghchi, M. N. Petrovich, F. Poletti, and D. J. Richardson
Opt. Lett. 44(17) 4367-4370 (2019)

Quantitative analysis for the effect of the thermal physical property parameter of adhesive on the thermal performance of the quadrupolar fiber coil

Zhuo Zhang and Fei Yu
Opt. Express 25(24) 30513-30525 (2017)

Air flowing induced thermo-optic effect for thermal sensitivity reduction in anti-resonant hollow core fibers

Yizhi Sun, Zhi Liang, Yulin Sheng, Shoufei Gao, Zhe Zhang, Anqing Jia, Yingying Wang, and Wei Ding
Opt. Express 30(13) 23138-23148 (2022)