The study of acoustic properties of P205-doped silica fiber

Law, Pi-Cheng

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https://hdl.handle.net/2142/32027 Copy

Description

Title

The study of acoustic properties of P205-doped silica fiber

Author(s)

Law, Pi-Cheng

Issue Date

2012-06-27T21:28:55Z

Director of Research (if dissertation) or Advisor (if thesis)

Swenson, Gary R.

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Acousto-optics
• Fiber characterization
• Fiber materials
• Fiber measurements
• Nonlinear optics
• Stimulated Brillouin scattering

Abstract

Silica-based optical fibers have been applied to numerous fields. The interactions between acoustic phonons and the optical wave are involved in several of these applications. A significant stimulated scattering mechanism observed is stimulated Brillouin scattering (SBS), resulting in strong backward scattering typically within the optical fiber core. SBS has become one of the significant factors limiting the power transmitted in an optical fiber. Through investigating acoustic properties with temperature and strain effects, novel fibers can be developed by decreasing SBS of high power laser systems for optical remote sensing, or by increasing sensitivity to temperature or strain for distributed fiber-optic sensing systems. This thesis presents measurements and modeling of the P2O5 doping effect on the acoustic damping and temperature sensitivity coefficients of silica fibers. The Brillouin gain spectrum of a highly P2O5-doped fiber is measured at different temperatures. Its thermo-acoustic coefficients (TAC) and thermo-optic coefficients (TOC) are determined. In addition, its acoustic velocity is found to be much less dependent on temperature. We present similar analysis for the P2O5 doping effect on the strain sensitivity coefficients of silica fibers. The strain-optic coefficient (SOC) and the strain-acoustic coefficient (SAC) of bulk P2O5 are determined by investigating the Brillouin gain spectrum of a heavily P2O5-doped fiber and a pure silica fiber at different strains. The Pockels coefficients p11 and p12 for bulk P2O5 are also estimated via Brillouin gain measurements. The experimental data and analysis results are extremely useful for designing optical and acoustic profiles of optical fibers for any applications where Brillouin scattering occurs.

Graduation Semester

2012-05

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http://hdl.handle.net/2142/32027

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Copyright 2012 Pi-Cheng Law

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