Nonlinearity Engineering and the Tale of the Two Laser Inventions
F. Ömer Ilday,
Physics Department, Bilkent University
Ultrafast science impacts on nearly all areas of modern technology, and
femtosecond lasers are invaluable tools in applications covering
diverse fields such as materials processing, biomedical imaging, and
frequency metrology. Advances in ultrafast science have always gone
hand-in-hand with the developments in laser technology. A femtosecond
laser is, however, a complex device, rendering their operation
difficult even in a research laboratory in the hands of an experienced
research. Fiber lasers are hailed as the solution thanks to their
operational simplicity. However, the propagation of short pulses in
optical fiber necessarily leads to high intensities, ultimately
limiting the performance of these lasers through the onset of nonlinear
The presence of strong nonlinear effects in fiber laser cavities drives
rich and complex dynamics. The dynamics is interesting from a
fundamental perspective, in addition to holding the key to technical
progress. The nonlinear waves community has unraveled the fascinating
world of solitons, and similaritons (self-similarly evolving pulses)
through experiments in fibers. For the last decade, fiber lasers have
been allowing us to observe these waves subject to dissipative effects
and periodic boundary conditions.
In this talk, I will tell the tale of two inventions; the similariton
laser  and the soliton-similariton laser  and how we have come to
understand femtosecond laser physics better through the lens of these
developments. The similariton laser was the first laser design to work
with nonlinear effects, rather than trying to avoid or compensate for
them. This laser has been duplicated in countless laboratories in the
world and forms the basis of at least half a dozen commercial products.
Recently, the soliton-similariton laser goes one step further, where
the propagation dynamics are, in fact, everywhere nonlinear. This new
design combines, for the first time, two distinct nonlinear waves
within the same cavity, matched by strong dissipative transitions, to
yield extremely robust and low-noise performance.
Wednesday, April 14th. 2010, FENS L035, 13:40 P.MIn the final part, I
will give a short overview of the applications being pursued at Bilkent
University, from femtosecond nanosurgery and material processing to
ultra-precise RF signal generation.
 Ilday et al., Physical Review Letters, 2003.
 Oktem et al., Nature Photonics, 2010.
Dr. F. Ömer Ilday received his BS in physics from Bogazici University
in 1998 and PhD from Cornell University in 2003. His accomplishments
include the invention of the similariton laser, the soliton-similariton
laser, several lasers with record-breaking performance, the first
mode-locked laser to use a photonic crystal fiber for dispersion
control, his contributions to the modeling of fiber lasers and
amplifiers. He is the author of more than 30 journal papers, 100
conference contributions and has given more than 40 invited seminars at
institutions throughout the world. He holds 4 issued US patents. He is
a recipient of the prestigious TÜBA-GEBIP award by the Turkish Academy
of Sciences. His contributions to the scientific community include
serving as topical editor of Optics Letters since 2008.
Wednesday, April 14th. 2010, FENS L035, 13:40 P.M