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SUMMARY:Photonic topological insulators
DTSTART:20130527T140000
DTSTAMP:20260407T095328Z
UID:d751d609d8ea7205080b9130b33e34af5678be53f9d794bfe8e15808
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Mikael Rechtsman\, Physics Department and Solid State Insti
 tute\, Technion\nBio: Princeton University\, Ph.D. (2003-2008)\nMassachuse
 tts Institute of Technology\, S.B. (2000-2003)\nResearch Interests:\nLinea
 r and nonlinear Complex Photonic Structures\nPhotonic Floquet Topological 
 Insulators\nEffective magnetism at optical frequencies\nHoneycomb lattices
 : "optical graphene"\nBand gaps in amorphous photonic crystals for soft ma
 tter\nPhotonic quasicrystals\nNegative radiation pressure\nI will present 
 the experimental demonstration of topological insulators (TIs) where the p
 ropagating field is electromagnetic (in this case\, visible light)\, rathe
 r than electronic.  In solid state TIs\, topological protection is achiev
 ed by virtue of the Kramers degeneracy\, which doesn't apply to photons (s
 ince they are bosons).  Therefore\, another mechanism is required.  Theo
 retical proposals for achieving photonic TIs have included: aperiodic coup
 led resonator arrays\; coupled optical cavities\; birefringent metamateria
 ls\; and temporally modulated photonic crystal slabs.\nOur system\, which 
 is quite distinct from the previously proposed structures\, is composed of
  an array of evanescently coupled helical waveguides arranged in a honeyco
 mb lattice.  In this system\, light diffracts according to the Schröge
 r eqution\, where the time coordinate is replaced by the distance of propa
 gation\, and the waveguides act as potential wells.  The helicity of the 
 waveguides induces a fictitious\, time varying electric field\, and the st
 ructure thus becomes equivalent to a Floquet TI.  The resulting 2+1 dimen
 sional "photonic lattice" exhibits topologically protected edge states\, a
 nd we demonstrate their presence and probe their properties experimentally
 .\nI will show a number of consequences of topological protection\, such t
 otal absence of backscattering at sharp corners\, and scatter free propaga
 tion around edge defects.  Our setting can potentially allow for the stud
 y of mean field interactions (through optical nonlinearity)\, and the effe
 cts of highly tunable disorder in TIs.  Photonic TIs have been suggested 
 for a number of applications\, including highly robust optical delay lines
 \, on chip optical diodes\, and spin cloaked photon sources.
LOCATION:MXC 315
STATUS:CONFIRMED
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