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CREOL Spring Colloquium Series: Oren Cohen- New (chiral) light on nonlinear laser spectroscopy

Thursday, March 11, 2021 noon to 1 p.m.

Abstract: Selection rules in nonlinear optics determine which radiation modes are allowed/forbidden in nonlinear processes. Traditionally, the theory accounts for symmetries of the medium only. I will first present a more general theory in which the selection rules are derived from the space-time symmetries of the entire system: medium and light. Utilizing this approach, we discovered numerous new selection rules, e.g. processes that conserve the polarization ellipticity of the radiation. I will then present applications of the new theory for ultrafast spectroscopy and for describing a new type of light – ‘synthetic chiral light’. This light is characterized by a new intrinsic property of electromagnetic fields that evaluates the chirality of the polarization vector trajectory in time. Synthetic chiral light interacts with chiral matter extremely selectively, even in processes in which circularly polarized beams act as achiral objects.

Speaker Bio: Oren Cohen did his PhD with Mordechai Segev at Technion and post-doc with Profs. Margaret Murnane and Henry Kapteyn in JILA, University of Colorado at Boulder. Oren returned to Technion in 2009 to setup his research group and Lab in ultrafast optics. His current research interests includes high harmonic generation, ultrafast spectroscopy and ultrahigh-speed microscopy.
Oren's significant contributions include the discoveries of incoherent solitons in lattices and in non-instantaneous nonlinear media during his PhD thesis, his proposal and experimental demonstration of all-optical quasi-phase matching of high harmonic generation during his post-doctoral period, and as PI, the development and applications of the first scheme for generation of bright high-order harmonics with fully controlled polarization, the proposal and demonstration of the first technique for experimental demonstration of 3D spatiotemporal solitons in homogeneous media, and the proposal and development of time-resolved imaging by multiplexed ptychography (TIMP) for nanometric ultrahigh-speed microscopy.
When not chasing photons, Oren may be found in the basketball court, playing for the Technion team or with his four boys.

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