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URL:http://murmitoyen.com/events/vanille/detail/833292-topological-and-chir
 al-lasing-in-micro-resonator-arrays-philippe-st-jean-cnrs-paris
LOCATION:Université de Montréal - Pavillon J.-Armand-Bombardier\, 5155\, 
 chemin de la rampe \, Montréal\, QC\, Canada\, H3T 2B2
SUMMARY:Topological and chiral lasing in micro-resonator arrays - Philippe 
 St-Jean (CNRS Paris)
DESCRIPTION:Topological and chiral lasing in micro-resonator arraysPresenta
 tion given in English Philippe St-JeanCentre de Nanosciences et de Nanotec
 hnologiesCNRS - Université Paris-Sud\, Université Paris-Saclay\, France

 \nAbstract: Engineering non-trivial symmetries in photonic structures is a
  very promising avenue for developing new generations of optical devices p
 resenting exotic yet technologically relevant assets\, e.g. topological pr
 otection [1] and chiral transport of light [2]. In this context\, arrays o
 f coupled semiconductor micro-resonators are particularly advantageous\, b
 ecause (1) they allow engineering well-defined potential landscapes for ph
 otons [3]\, and (2) embedded quantum wells in these structures can provide
  optical gain. In this presentation\, I will show how these advantages of 
 micro-resonator arrays can be harnessed for developing laser sources where
  the architecture of the cavity gives rise to resonating modes exhibiting 
 genuinely novel properties.
\nIn the first part of the presentation\, I wi
 ll show how we took profit of these advantages to demonstrate the first re
 alization of a topological laser [4]\, i.e. a laser where the resonating m
 ode is intrinsically protected against external perturbations by the under
 lying topology of its architecture. To do so\, we implemented a 1-dimensio
 nal micro-resonator array that exhibits well-defined topological propertie
 s leading to the emergence of robust edge states. Then\, using the gain pr
 ovided by the embedded quantum wells\, we triggered lasing in one of these
  topological edge states\, and demonstrated the immunity of this lasing ac
 tion against optically-induced perturbations.
\nThen\, I will present a re
 cent work [5] where we used hexagonal molecules of coupled micro-resonator
 s to trigger lasing in a mode carrying a well-defined and optically tunabl
 e orbital angular momentum (OAM). OAM is an unbounded degree of freedom of
  light associated to phase vortices in helical wavefronts. Such an unbound
 ed Hilbert space appears extremely advantageous in many technologically re
 levant areas\, such as classical and quantum information encoding\, optica
 l manipulation and optomechanics. In this work\, we developed a novel sche
 me based on the spin-orbit interaction of photons in these hexagonal molec
 ules to demonstrate\, for the first time in a fully integrated device\, th
 e optical control of the chirality of a lasing mode (i.e. carrying either 
 a clockwise or counter-clockwise phase twist). Our results thus pave the w
 ay to the development of ambitious protocols\, e.g. in quantum cryptograph
 y\, based on the ultrafast control of OAM.
\nReferences:[1] L. Lu. et al..
  Nat. Photon. 8\, 821 (2014)\; T. Ozawz et al. arXiv: 1802.04173v1 (2018)[
 2] P. Lodahl et al. Nature 541\, 473 (2017)[3] M. Milicevic et al. Phys. R
 ev. Lett. 118\, 107403 (2017)\; F. Baboux et al. Phys. Rev. B 95\, 161114 
 (R) (2017) [4] P. St-Jean et al. Nat. Photon. 11\, 651 (2017)[5] N. Carlon
  Zambon\, P. St-Jean et al. arXiv:1806.04590 (2018)
\nPhilippe St-Jean is 
 a postdoc researcher in the group of Jacqueline Bloch\, a CNRS research ce
 nter based in Paris\, France.
\nCette conférence est présentée par le 
 RQMP Versant Nord du Département de physique de l'Université de Montr
 éal et de Génie physique de la Polytechnique.
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