In Optics parlance, the surface of a light cone represents all possible combinations of spatial and angular frequencies of electromagnetic waves in free-space. For instance, a monochromatic beam is the result of a circular trajectory on the light cone (a horizontal conic section) while a typical ultrafast wave packet is represented by a finite area on the cone’s surface. In my talk, I will discuss a novel family of diffraction-free ultrafast light pulses that are localized both in time and one transverse dimension. Such pulses, dubbed space-time wave packets, are a result of ‘classically-entangled’ spatio-temporal spectra corresponding to more general conic sections of a light cone such as the hyperbola, the parabola, and the ellipse. Space-time wave packets are experimentally realized in the form of light sheets (one-dimensional beams) via a two-dimensional pulse shaping scheme and exhibit features such as superluminal and subluminal group velocities, arbitrary beam profiles, self-healing, and even, if desired, transverse acceleration in the spatio-temporal domain--all in free space. Moreover, the experimental scheme enables to independently control any two parameters of space-time wave packets out of three, namely, the pulse duration, the group velocity, and the transverse beam profile of the central peak. Space-time wave packets are poised to result in novel light-matter-interaction schemes due to their flexibility to tailor their dispersion relation to match any material or physical mechanism directly from free space with the ease of a programmable spatial light modulator.

Hasan Esat Kondakci is a postdoctoral research fellow in CREOL, the College of Optics & Photonics at the University of Central Florida. Currently I'm working in Prof. Ayman Abouraddy's research group on a number of topics such as diffraction-free space-time beams, coherence phenomena, and passive 3D scene discovery through coherency imaging.

He received his PhD from CREOL in 2015 under supervision of Prof. Bahaa Saleh and studied photon statistics in disordered lattices.

Researchers should cite this work as follows:

• Hasan Esat Kondakci (2018), "Diffraction-Free Space-Time Wave Packets," https://nanohub.org/resources/28454.

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