Photonic topological insulators
Event details
| Date | 27.05.2013 |
| Hour | 14:00 |
| Speaker |
Dr Mikael Rechtsman, Physics Department and Solid State Institute, Technion Bio: Princeton University, Ph.D. (2003-2008) Massachusetts Institute of Technology, S.B. (2000-2003) Research Interests: Linear and nonlinear Complex Photonic Structures Photonic Floquet Topological Insulators Effective magnetism at optical frequencies Honeycomb lattices: "optical graphene" Band gaps in amorphous photonic crystals for soft matter Photonic quasicrystals Negative radiation pressure |
| Location |
MXC 315
|
| Category | Conferences - Seminars |
I will present the experimental demonstration of topological insulators (TIs) where the propagating field is electromagnetic (in this case, visible light), rather than electronic. In solid state TIs, topological protection is achieved by virtue of the Kramers degeneracy, which doesn't apply to photons (since they are bosons). Therefore, another mechanism is required. Theoretical proposals for achieving photonic TIs have included: aperiodic coupled resonator arrays; coupled optical cavities; birefringent metamaterials; and temporally modulated photonic crystal slabs.
Our system, which is quite distinct from the previously proposed structures, is composed of an array of evanescently coupled helical waveguides arranged in a honeycomb lattice. In this system, light diffracts according to the Schröger eqution, where the time coordinate is replaced by the distance of propagation, and the waveguides act as potential wells. The helicity of the waveguides induces a fictitious, time varying electric field, and the structure thus becomes equivalent to a Floquet TI. The resulting 2+1 dimensional "photonic lattice" exhibits topologically protected edge states, and we demonstrate their presence and probe their properties experimentally.
I will show a number of consequences of topological protection, such total absence of backscattering at sharp corners, and scatter free propagation around edge defects. Our setting can potentially allow for the study of mean field interactions (through optical nonlinearity), and the effects 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.
Our system, which is quite distinct from the previously proposed structures, is composed of an array of evanescently coupled helical waveguides arranged in a honeycomb lattice. In this system, light diffracts according to the Schröger eqution, where the time coordinate is replaced by the distance of propagation, and the waveguides act as potential wells. The helicity of the waveguides induces a fictitious, time varying electric field, and the structure thus becomes equivalent to a Floquet TI. The resulting 2+1 dimensional "photonic lattice" exhibits topologically protected edge states, and we demonstrate their presence and probe their properties experimentally.
I will show a number of consequences of topological protection, such total absence of backscattering at sharp corners, and scatter free propagation around edge defects. Our setting can potentially allow for the study of mean field interactions (through optical nonlinearity), and the effects 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.
Links
Practical information
- General public
- Free
Organizer
- Nicola Marzari <[email protected]>
Contact
- Nicola Marzari <[email protected]>