High Pressure Chemical Vapor Deposition to Obtain Step-Index and Bragg Optical Fibers
- Author
- Chaudhuri, Subhasis
- Published
- [University Park, Pennsylvania] : Pennsylvania State University, 2017.
- Physical Description
- 1 electronic document
- Additional Creators
- Badding, John V.
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- Graduate Program
- Restrictions on Access
- Open Access.
- Summary
- Optical fibers are usually made of thin glass strands that can transmit light and have become the backbone of modern communication technology. Apart from communication, they are used in medical applications, sensing, cutting and drilling, as fiber lasers etc. Traditionally optical fibers are made by drawing preforms under high temperature thereby limiting the materials that can be incorporated to mostly glass and polymers. Incorporation of other materials in optical fibers can greatly increase their functionalities and open up several other applications that were previously not possible with these fibers. Badding lab came up with an alternate strategy of high pressure chemical vapor deposition (HPCVD) inside silica capillaries to obtain multimaterial fibers. Various metals, semiconductors and insulators can be deposited inside silica capillaries using HPCVD thereby enabling new fiber functionalities. Chapter 1 offers a brief journey into the history of optical fibers and the variety of different fibers that are currently available. Electromagnetic waves are governed by Maxwells equations, which can be solved to understand the propagation of light through optical fibers. However, rigorous solution for different fiber structures can become complicated and hence numerical modeling methods can help understand light propagation more easily. I have used modeling using COMSOL Multiphysics software to understand light propagation in different types of optical fibers, which forms the basis of chapter 2. HPCVD inside silica capillaries has been established as a great technique to fabricate multimaterial multifunctional fibers. However, this requires precise understanding of the deposition chemistry inside these confined capillaries under high temperature and pressure, which has been enumerated in chapter 3. The main focus of this dissertation is the fabrication of two different types of optical fibers solid core step-index and hollow core Bragg fibers via HPCVD. The silica capillaries can be completely filled with semiconductors (such as silicon, germanium, silicon germanium) to form step-index optical fibers that guide light by total internal reflection. These semiconductors have wider transparency windows and larger nonlinear optical coefficients than silica and hence the semiconductor core fibers can have numerous optical applications, which I explain in chapter 4. HPCVD can also be used to fabricate hollow core optical fibers such as Bragg fibers. Bragg fibers have hollow cores bound by alternating concentric layers of high and low refractive index materials. Such structure can confine light of particular wavelength (depending on the geometry) in the hollow core thereby enabling low loss transmission. I talk in details about the fabrication of all-inorganic Bragg fibers using HPCVD technique. These fibers have optical transmission higher than standard polymer Bragg fibers available currently and can transmit very high peak power (density of 500 TWcm-2). They are currently being tested for high harmonic generation in the hollow cores to generate commercial tabletop X-Ray sources for imaging and ultrafast lasers.
- Other Subject(s)
- Genre(s)
- Dissertation Note
- Ph.D. Pennsylvania State University 2017.
- Reproduction Note
- Microfilm (positive). 1 reel ; 35 mm. (University Microfilms 28230391)
- Technical Details
- The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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