Giving to CREOL
CREOL, The College of Optics & Photonics

CREOL Student of the Year Finals 2009

Thursday, April 2, 2009 12:00 PM to 1:00 PM
CREOL Room 102 and 103


  • Timothy S. McComb
  • Sergiy Mokhov
  • Oleksandr Savchyn

Each student will give a 12 minute talk with 3 minutes for questions. 

Titles and Abstracts:

"Spectral and Temporal Control of High Power Large Mode Area Thulium Fiber Lasers"

Timothy S. McComb

Thulium fiber lasers are one of the best choices today for filling the increasing need for eyesafe laser systems designed for atmospheric propagation over long distances due to their high efficiency, compact size, beam quality and broad wavelength spectrum. The development of transportable high power thulium fiber laser systems with high operational stability as well as spectral and temporal control to fill the needs posed by these applications will be discussed. A tunable fiber laser system with narrow linewidth and capable of 200W output power is demonstrated along with work on other pulsed and spectrally controlled systems.


"Moiré Filter in Volume Bragg Grating: theoretical suggestion and experimental" implementation.

Sergiy Mokhov

We propose narrow-band moiré filter in volume Bragg grating. Its spectral properties are analyzed in terms of general approach to reflection problems based on our new theoretical concept – Strength of Reflection. An experimental demonstration of a moiré reflecting Bragg grating in photo-thermo-refractive glass was done. A robust solid-state filter with narrow bandwidth of 50 pm, transmission peak higher than 95 %, and large aperture, was demonstrated. Moiré filters in volume Bragg grating are tunable via transverse degrees of freedom and are tolerant to high power laser radiation. Possible applications in laser industry are discussed.


"Sensitizers of erbium in silicon-rich SiO2: nanocrystals or luminescence centers?"

Oleksandr Savchyn

The implementation of silicon photonics requires the development of a compact silicon-compatible light source. One of the possible routes for its realization is to use the emission from optical centers incorporated into silicon-based matrices and sensitized with dopants. It has long been thought that silicon nanocrystals can be used as efficient and dominant sensitizers of erbium in silicon-doped SiO2. In the current presentation it will be shown that the indirect excitation of erbium in this material does not require the presence of silicon nanocrystals. This conclusion clarifies a number of previously unexplained results and opens new opportunities in the field of silicon photonics.

Biographical Notes:

Timothy McComb is a 4th year Ph.D. student at the Townes Laser Institute, CREOL, The College of Optics and Photonics, UCF. He earned his M.S. in Optics from CREOL in 2006 and his B.S. in Engineering Physics from the University of Arizona in 2005. He has interned in industry at Coherent Inc. and Nufern Inc. His Ph.D. work covers spectral and temporal control of high power, large mode area thulium fiber lasers, development of lasers for eyesafe applications and large mode area fiber technology. He has been part of 5 peer-reviewed publications, 12 conference papers and has 3 patents pending.

Sergiy Mokhov was born in Odessa, Ukraine, on August 11, 1974. While in Middle School, he won regional Olympics in Physics, and was invited to Physical-Mathematical boarding school in Kiev in 1988. Studying there, he won twice the Ukrainian National Olympics in Physics (first prize in 1990). Then he studied at the chair of Theoretical Physics of the Shevchenko National University in Kiev and graduated in 1996. he was accepted to PhD program of that University, and simultaneously was working in Bogolyubov Institute for Theoretical Physics on nuclear physics until 2000. Due to shortage of University funding, he started to work for commercial companies. Sergiey joined CREOL in 2004, where he worked first with Prof. Christodoulides; we wrote two papers together with his group. From 2006 through present, he has been working with Prof. Zeldovich and with Dr. Glebov’s group.

Oleksandr Savchyn received his M.S. in Optics from CREOL in 2007 and his Specialist degree (B.S. & M.S.) in Physics from the Lviv ‘Ivan Franko’ National University (Lviv, Ukraine) in 2002. During 2002 - 2004 he worked as a research assistant at the Department of Physics of Lviv ‘Ivan Franko’ National University. In 2004 he joined the Nanophotonics and Near-field Optics group at CREOL where he currently pursues his Ph.D. studies. His scientific interests include semiconductor photonics, indirect excitation of erbium in glass matrices, optical properties of silicon nanocrystals. He is a student member of OSA, SPIE, IEEE/LEOS, MRS.

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