Incoherent light in tapered graded-index fibre: a study of transmission and modal noise

Choochalerm, Piyamas, Martin, Bill, Jones, Hugh, Usher, Sarah, Wright, Thomas and Yerolatsitis, Stephanos (2023) Incoherent light in tapered graded-index fibre: a study of transmission and modal noise. Optical Fiber Technology, 75: 103140. pp. 1-9. ISSN 1068-5200

Copy

We investigated the impact of taper length on light transmission through tapered graded-index fibres. We tested commercial fibres from Thorlabs and a custom graded-index fibre using both coherent and incoherent light sources. Our experimental results show optimum performance for taper transition lengths of 25 mm, although our simulations suggest further improvement may be possible for even shorter transition lengths. We also measured the modal noise power fluctuations caused by bending the fibre. Here, we observe that the custom fibre tapers have the highest transmission but suffer from the most modal noise. Accordingly, we find that the commercial graded-index fibre tapers promise practical usage as a beam mode-field converter, as they have lower power fluctuations but retain relatively high transmission if compared to commercial small core step-index fibre.

Item Type	Article
Identification Number	10.1016/j.yofte.2022.103140
Additional information	© 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license, http://creativecommons.org/licenses/by/4.0/
Keywords	adiabatic tapered fibre, fibre transmission, graded-index fibre, high-resolution spectrograph, incoherent light source, modal noise, numerical aperture characterisation, control and systems engineering, electronic, optical and magnetic materials, atomic and molecular physics, and optics, instrumentation, electrical and electronic engineering
Date Deposited	15 May 2025 15:01
Last Modified	25 Feb 2026 00:57