University of Illinois Urbana-Champaign

Determination of the Thermo-Optic Coefficient of Germanium-Doped Fibers

Fabbro Barroso, Riccardo Enrique

This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.

Permalink

https://hdl.handle.net/2142/88909

Description

Title
Determination of the Thermo-Optic Coefficient of Germanium-Doped Fibers
Author(s)
Fabbro Barroso, Riccardo Enrique
Contributor(s)
Dragic, Peter
Issue Date
2015-12
Keyword(s)
  • Brillouin scattering
  • modal index
  • thermo-optic coefficient
  • germanium-doped fibers
Abstract
Light transmission through optical fiber depends on the fiber's refractive index profile, which in standard single mode transmission fibers is typically a simple step index given by the core and cladding. If the refractive index of the fiber undergoes a change due to pressure variations in the glass while light is being transmitted through it, an effect known as Brillouin scattering occurs. Brillouin scattering is a strong parasitic effect that limits the power that can be transmitted in coherent systems. The thermo-optic effect has a strong impact on Brillouin scattering and thus by analyzing this effect it is possible to obtain the thermo-optic coefficient of a fiber's glass core. The thermo-optic coefficient is an important characteristic of optical glasses because it relates the change in a material's refractive index to the temperature that the material experiences. Germanium-doped fibers were chosen due to the element's range of very useful characteristics for light transmission. The measurement procedure is as follows. A length of germanium-doped fiber is incorporated into a ring fiber laser system with known characteristic and is then submerged in a crucible of water and exposed to temperatures ranging from room temperature to slightly below boiling. The change in laser free spectral range of a particular harmonic is measured every 5 degrees Fahrenheit, enabling the determination of the derivative of free spectral range versus temperature, which in turn enables the determination of several other characteristics of the fiber, namely its thermo-optical coefficient.
Type of Resource
text
Language
en
Permalink
http://hdl.handle.net/2142/88909

Owning Collections

Senior Theses - Electrical and Computer Engineering PRIMARY
The best of ECE undergraduate research