Temperature-insensitive fused-tapered fiber couplers based on negative thermal expansion material coating

TL;DR

This paper introduces a novel fiber coupler design using negative thermal expansion coatings to achieve high temperature stability, verified through modeling and experiments, suitable for precision optical applications.

Contribution

It presents a new coating method with negative thermal expansion material to significantly improve fiber coupler temperature stability, supported by finite-element modeling and experimental validation.

Findings

Temperature stability improved by over an order of magnitude

Achieved stability of 1.2*10^-5/K in splitting ratio

Applicable to extreme temperature environments in optical systems

Abstract

A new method based on negative thermal expansion material coating is proposed to realize temperature insensitive fiber coupler. By coating a layer of modified epoxy resin with a negative thermal expansion coefficient onto the coupling region of fiber coupler, a stable splitting ratio over a wide temperature range can be achieved. A finite-element model for simulating the influence of thermal fluctuations on fused-tapered fiber coupler's splitting ratio is built and verified via experimental test. Furthermore, using this model, the influence of the thickness, length, and thermal expansion coefficient of the coating material on the splitting ratio is studied. Through adjusting the parameters of the coating, the temperature stability of the fiber coupler splitting ratio can be improved by more than one order of magnitude and improved to 1.2*10-5/K. The temperature-insensitive fused-tapered fiber coupler can find important application in optical precision measurement under extreme temperature environment, such as inter-satellite laser interferometry and high-precision fiber gyroscopes.