Coherent processes and applications of the slow and fast light phenomena in metastable helium at room temperature
type: Dataset
description: Many coherent processes can be observed when electromagnetic fields are applied to multi-level systems. Electromagnetically induced transparency (EIT) or coherent population oscillations (CPO) are resonant phenomena resulting in the cancellation of the absorption of the system for a probe field. EIT occurs in three-level systems and involves the coherence between two optically uncoupled levels, whereas two-level systems are sufficient to produce CPO which does not involve the dynamics of the coherences.A three-level Λ system can be isolated in a gas of metastable helium atoms at room temperature. When excited with circular polarizations, this system exhibits EIT resonances of a few tens of kHz. If this system is excited by linear polarizations and submitted to a weak magnetic field, the response of the system is given by the combination of these two phenomena, namely EIT and CPO. A narrow CPO transmission window of a few tens of kHz has then been observed.This kind of resonant phenomena is associated with very strong variations of the refractive index at the probe frequency, leading to major changes of the group velocity of a pulse propagating in the medium. Our experimental set-up allows us to observe slow light, fast light, and even negative group velocities. Insertion of such dispersive media inside an optical cavity has been suggested to increase the sensitivity of sensors such as laser gyroscopes, but their fundamental noise depends on the lifetime of photons inside the cavity. This is why the influence of highly dispersive media on the photon lifetime inside a cavity is studied experimentally and theoretically.
identifier: NNT: 2012PA112287
issued: 2026-05-15T10:49:37.489230
language: fr
modified: 2026-05-15T10:49:37.489237
contact point: Organization
  fn: CCSD
keyword: atomic-coherence
keyword: causalite
keyword: causality
keyword: cavite-optique
keyword: coherence-atomique
keyword: cpo
keyword: dispersive-medium
keyword: duree-de-vie-des-photons
keyword: eit
keyword: fast-light
keyword: infoeu-reposemanticsdoctoralthesis
keyword: lumiere-lente
keyword: lumiere-rapide
keyword: milieux-dispersifs
keyword: optical-cavity
keyword: photon-lifetime
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: slow-light
keyword: theses
landing page: https://theses.hal.science/tel-00772326

Coherent processes and applications of the slow and fast light phenomena in metastable helium at room temperature
type: Distribution
format: HTML
issued: 2026-05-15T10:49:37.615793
modified: 2026-05-15T10:49:37.426076
access URL: https://theses.hal.science/tel-00772326

test_moissonnage_selune
type: Agent