Simulation of Pulse Propagation in ZBLAN Fiber

by Ali Cox

supervisor:  Brian Washburn, Associate Professor of Physics

Kansas State University Physics Department  REU Program

This program is funded by the National Science Foundation through grant number PHYS-1461251.  Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Below, I describe the Project Overview, my Research Description, my Research Progress, and will eventually post my Final Presentation . Scroll all the way down to learn more About Me.  Finally, I've included some Useful Links

Project Overview: 

This research is motivated by the demand for a source of coherent light in the mid-infrared range (~3 microns wavelength). Light at this wavelength has many applications including medical treatment and sensitive particle detection, but it is difficult to produce. Femtosecond fiber lasers show a drastic decrease in power beyond 2 microns due to the absorptive properties of silica.

One solution to this problem is to use nonlinear fiber optics to downshift the frequency of an abundant source of coherent light whose wavelength is not far from 3 microns. However, this method is fruitless if done using silica fiber for the same reason that silica fiber lasers themselves fail to produce 3 micron light silica absorbs all light in the mid-infrared range. We thus look into a more exotic type of optical fiber called ZBLAN fiber. The letters in its name represent the various heavy metal-fluorine compounds it is doped with to make it transparent to mid-infrared light.

My research focuses on understanding the non-linear properties of this fiber and implementing them in code to be able to numerically simulate pulse-propagation through ZBLAN fiber.

Research Description:

The primary nonlinear optical effect I am concerned with in down-shifting the frequency of light is Stimulated Raman Scattering. Every fiber medium has a unique Raman gain signature that describes the rate at which energy is transferred from one frequency to every frequency below it. In order to be able to simulate pulse propagation in ZBLAN fiber, I must reconstruct the Raman response function by extracting information from the experimental ZBLAN Raman gain spectrum. Once I obtain the Raman response, my goal is to implement it in code and determine the pulse parameters required to see a shift toward 3 microns in the spectrum of an initial pulse pumped into ZBLAN fiber.

Final Presentation:  Click here to download my presentation in powerpoint format, and here for pdf.

About Me:  

I am a sophomore physics major at Reed College. Some of my favorite things to do are sailing, building things and seeing them work the way I planned, and just thinking about stuff.

If I had to choose one concrete aspect of this REU program that has helped me grow the most, it would be the bi-weekly responsibility to present on our research progress. I feel like these presentations have made me a better communicator and listener. But generally speaking, I think the time I spent with the people I met here and the connections I have made has been an overall maturating experience. I definitely recommend giving this program a shot to anyone who is considering it.

Useful Links: 

American Physical Society Statements on Ethics

American Institute of Physics