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Fictitious Fields in Phototonics: Topological Insulators and Pseudomagnetism

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CAMP Special Seminar by Mikael Rechtsman (Israel Institute of Technology)
When
09 September 2013 from 3:30 PM to 5:30 PM
Where
339 Davey
Contact Name
Contact Phone
(814) 863-0016
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In this talk I present two examples in which ‘fictitious fields’ can lead to surprising effects in photonic device physics that would be difficult (if not impossible) to achieve with real fields. The first is the case of photonic ‘topological insulators’ (TIs). TIs are solid-state materials that are insulators in the bulk but have intrinsic surface states that behave metallically, and are completely robust to any type of defects or disorder. In other words, when a surface electron wave in a TI encounters a defect, it simply goes around it without scattering, exhibiting – quite strikingly – perfect transmission. Here I present the observation of a ‘photonic topological insulator’ in the optical frequency range. The structure is an array of helical waveguides (the helicity generates a fictitious circularly-polarized electric field that leads to the TI behavior), and light propagating through it is ‘topologically forbidden’ from
scattering.

The second example is artificial magnetic fields (‘pseudomagnetism’) in photonic lattice structures. In nearly any material, magnetic response is negligible in the optical regime. Here I show experimental results demonstrating how straining the structure inhomogeneously is equivalent to an extremely strong magnetic field. The effect of the field is to collapse the spatial photonic spectrum into ‘photonic Landau levels’ – spectral regions of extremely high density-of-states. High photonic density-of-states enables strong light-matter interaction over large areas for a broad range of potential applications.

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