Robust method for finding the modes in a fibre with an unknown refractive index profile

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081731%3A_____%2F22%3A00559492" target="_blank" >RIV/68081731:_____/22:00559492 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12140/121400M/Robust-method-for-finding-the-modes-in-a-fibre-with/10.1117/12.2632808.short" target="_blank" >https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12140/121400M/Robust-method-for-finding-the-modes-in-a-fibre-with/10.1117/12.2632808.short</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1117/12.2632808" target="_blank" >10.1117/12.2632808</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Robust method for finding the modes in a fibre with an unknown refractive index profile

Popis výsledku v původním jazyce

The number of eigenmodes in an optical fibre depends on the wavelength of the excitation laser beam as well as on the exact geometry and refractive index profile of the fibre. The latter is often proprietary information and, when available, is only specified to within manufacturing tolerances. We here present a method for obtaining the number of fibre modes, as well as their shape, which requires no knowledge about the fibre, save a very approximate core radius. The method is based on the singular value decomposition (SVD) of a set of speckle patterns, measured at the output end of the fiber, which is then expanded onto a set of orthonormal basis functions. We present two possible approaches for the field expansion, where the first approach uses a generic orthonormal basis, such as Laguerre-Gaussian or Zernike functions, and the second one is a basis-free approach where the set of speckled patterns themselves form the basis. Using a set of simulated speckles patterns, we observed that the correct number of fibre modes can be obtained through the SVD decomposition, even at high levels of additive random noise. With a slight extension, using speckle patterns obtained at multiple excitation wavelengths (or equivalently, for different lengths of the same fiber) the method can also retrieve the shape of the actual fibre modes, by forming an appropriate linear combination of SVD modes.

Název v anglickém jazyce

Robust method for finding the modes in a fibre with an unknown refractive index profile

Popis výsledku anglicky

The number of eigenmodes in an optical fibre depends on the wavelength of the excitation laser beam as well as on the exact geometry and refractive index profile of the fibre. The latter is often proprietary information and, when available, is only specified to within manufacturing tolerances. We here present a method for obtaining the number of fibre modes, as well as their shape, which requires no knowledge about the fibre, save a very approximate core radius. The method is based on the singular value decomposition (SVD) of a set of speckle patterns, measured at the output end of the fiber, which is then expanded onto a set of orthonormal basis functions. We present two possible approaches for the field expansion, where the first approach uses a generic orthonormal basis, such as Laguerre-Gaussian or Zernike functions, and the second one is a basis-free approach where the set of speckled patterns themselves form the basis. Using a set of simulated speckles patterns, we observed that the correct number of fibre modes can be obtained through the SVD decomposition, even at high levels of additive random noise. With a slight extension, using speckle patterns obtained at multiple excitation wavelengths (or equivalently, for different lengths of the same fiber) the method can also retrieve the shape of the actual fibre modes, by forming an appropriate linear combination of SVD modes.

Druh

D - Stať ve sborníku

CEP obor

—

OECD FORD obor

10306 - Optics (including laser optics and quantum optics)

Projekt

<a href="/cs/project/EF15_003%2F0000476" target="_blank" >EF15_003/0000476: Holografická endoskopie pro in vivo aplikace</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Micro-Structured and Specialty Optical Fibres VII

ISBN

978-151065156-2

ISSN

—

e-ISSN

—

Počet stran výsledku

8

Strana od-do

(2022)

Název nakladatele

SPIE

Místo vydání

Bellingham

Místo konání akce

online

Datum konání akce

9. 5. 2022

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

000838075300021