Announcing the Final Thesis Defense of Weibin Zhu for the Degree of Master of Science in Optics and Photonics-Photonics Track
Friday, April 7, 2017 1:00 PM to Thursday, April 6, 2017 2:00 PM
CREOL Room A214
“Picosecond Yb-doped fiber amplifier”
Comparing to traditional bulk optical gain media, rare earth doped fiber is more compact, efficient, mechanical and thermal stable. With such characteristics, amplifiers based on rare earth doped fiber are one of the hottest topics of optics in recent years, and already play a vital role in many commercial applications such as telecommunications, fiber sensing applications, laser sources amplification for medical imaging, and so forth. In 1987, the erbium-doped fiber amplifier (EDFA) was presented by R. J. Mears et al., later the Thulium doped fiber amplifier (TDFA) and the Praseodymium doped fiber amplifier (PDFA) were introduced for amplification in S-band and 1300nm region respectively. Among all these RDFAs, the EDFA is the most popular one since its amplification region is the one which widely used in optical fiber communication.
However, in high power amplification, the ytterbium doped fiber amplifier (YDFA) are more attractive. Because it can provide a wide wavelength range amplification. Apart from that, since YDFA can avoid excited state absorption and concentration quenching problem, moreover it can easily reach a high concentration of rare earth ions, thus it can provide much higher output power, high power conversion efficiency, and require shorter fiber length. With so many advantages, YDFAs attracted so much interest and already play an important role on high power application. Its broad gain bandwidth also makes it ideal in ultrashort optics application, and its wide pump wavelength allows a wide range of pumping scheme choices.
The overall purpose of this thesis is to investigate YDFA theoretically and experimentally by building a numerical model and a two-stages YDFA setup. The active fiber used in the experiment is a polarization-maintaining large mode area (LMA) double-clad ytterbium doped fiber (Nufern PLMA-YDF-25/250-VIII), and the setup is in free space configuration. The output mode is monitored though a CCD camera, both the output spectra and the output average power have been investigated and will be discussed in following chapters.
This thesis is arranged in six chapters. In Chapter 2, theoretical background of this thesis, such as basic knowledge of fiber optics, fabrication of rare earth doped active fiber, pumping scheme, and angle cleaving, are provided. Chapter 3 show how the numerical model is developed and solved though iteration. The experiment setup is presented in detail in Chapter 4. All the measurement result and discussion are reported in Chapter 5. And finally, Chapter 6 will make a conclusion and give some recommendations about how to improve the experiment setup to gain a better result.
Major: Master of Science in Optics and Photonics-Photonics Track
Educational Career: B.S. Optical Information Science & Technology, 2015, South China Normal University, China
Committee in Charge:
Dr. Rodrigo Amezcua (Chair)
Dr. Axel Schulzgen
Dr. Sasan Fathpour
Approved for distribution by Dr. Rodrigo Amezcua, committee chair, on March 28, 2017
The public is welcome to attend.
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