End-Capping Hollow-Core Fibers With Suppressed Coupling Into Higher-Order Modes

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21230%2F24%3A00374606" target="_blank" >RIV/68407700:21230/24:00374606 - isvavai.cz</a>
Result on the web
<a href="https://doi.org/10.1109/JSTQE.2024.3381797" target="_blank" >https://doi.org/10.1109/JSTQE.2024.3381797</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1109/JSTQE.2024.3381797" target="_blank" >10.1109/JSTQE.2024.3381797</a>

Result language
angličtina
Original language name
End-Capping Hollow-Core Fibers With Suppressed Coupling Into Higher-Order Modes
Original language description
We propose a hollow-core fiber (HCF) end-cap that incorporates a short segment of a single-mode fiber (SMF) that serves as a modal filter. To adapt the end-cap input and output beam to the desired size, the SMF was fusion spliced with short segments of mode-field adapting graded index (GRIN) fibers on both sides. The end-cap is anti-reflective coated to minimize insertion loss and parasitic reflections. The presented proof-of-concept experiments show its ability to suppress coupling into HCFs' higher-order modes. For example, without any end-cap, the extinction ratio between the LP 11 and the fundamental mode was found to be as low as 9 dB when coupling light from a free-space beam that was misaligned by as little as 1.1 ∘ . This was improved to 23 dB when inserting the developed end-cap. Such small angle misalignment often exists when aligning the input beam with 3-axis (x,y,z) stages only (rather than 5-axis that also include pitch and yaw). Finally, we glued the end-cap with the HCF, providing hermetic sealing to the HCF input/output. This is of interest for stable operation in applications that use free-space light launch or require HCF output into free space.
Czech name
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Czech description
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Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
20201 - Electrical and electronic engineering

Project
<a href="/en/project/FW03010171" target="_blank" >FW03010171: Fiber optic resonator structures for sensoric systems</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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