Department of Physics, Bilkent University
15 October 2015, Thursday, 14:40
Cavid Erginsoy Seminar Room, Physics Department, 3rd floor
In nature, structure and functionality effortlessly emerge from nonlinear processes subject to stochastic effects, often shaped by nonlinear feedback mechanisms. While this is ubiquitous all around us, its intentional use in human technology remains relatively rare. I assert that it is possible to exploit these principles to achieve superior technological functionalities and that photonics is a particularly fertile platform to demonstrate this vision, which I refer to as “Nonlinearity Engineering”.
This talk will review some of the advances we have made as we systematically develop this concept into an actionable capability,starting with exploiting self- similarity to turn what used to be severe limitations from optical nonlinearities to an advantage for ultrafast fiber lasers. Then, I will move on to introduce Nonlinear Laser Lithography — how we use nonlocal and nonlinear self-interference of a laser beam to fabricate self-assembled metal/metal-oxide nanostructure on various surfaces with unprecedented uniformity, solving a problem that dates back to 1965. I will then describe application of Nonlinear Laser Lithography to effortlessly create the first 3D photonic devices deep inside silicon through a different nonlocal effect. We also exploit the nonlinear interactions of femtosecond pulses with biological tissue: We use ablation cooling, a technique routinely used in rocket design since 1950’s, but so-far overlooked in optics, to achieve heat-damage -free removal of tissue at high speed. Finally, I will talk about our ongoing efforts to apply Nonlinearity Engineering to self-assembly of complex nanomaterials.
 B. Oktem, C. Ülgüdür and F. Ömer Ilday, “Soliton-similariton fibre laser,” Nature Phot., 4, 307 (2010).
 B. Oktem, I. Pavlov, S. Ilday, H. Kalaycıoglu, A. Rybak, S. Yavas, M. Erdogan and F. Ö. Ilday, “Nonlinear laser lithography for indefinitely large-area nano structuring with femtosecond pulses,” Nature Photon. 7, 897–901 (2013).
Reminder: Tea and cookies will be in the seminar room before the seminar.