title: Density of photon states in dye-doped chiral nematic liquid crystal cells in the presence of losses and gain.
abstract: We calculate the density of photon states (DOS) of the normal modes in dye-doped chiral nematic liquid crystal (LC) cells in the presence of various loss mechanisms. Losses and gain are incorporated into the transmission characteristics through the introduction of a small imaginary part in the dielectric constant perpendicular and along the director, for which we assume no frequency dispersion. Theoretical results are presented on the DOS in the region of the photonic band gap for a range of values of the loss coefficient and different values of the optical anisotropy. The obtained values of the DOS at the photonic band gap edges predict a reversal of the dominant modes in the structure. Our results are found to be in good agreement with the experimentally obtained excitation thresholds in chiral nematic LC lasers. The behavior of the DOS is also discussed for amplifying LC cells providing additional insight to the lasing mechanism of these structures.
authors.affiliation: Centre of Molecular Materials for Photonics and Electronics, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
authors.forename: Th K
authors.initials: TK
authors.lastname: Mavrogordatos
authors.forename: S M
authors.initials: SM
authors.lastname: Morris
authors.forename: F
authors.initials: F
authors.lastname: Castles
authors.forename: P J W
authors.initials: PJ
authors.lastname: Hands
authors.forename: A D
authors.initials: AD
authors.lastname: Ford
authors.forename: H J
authors.initials: HJ
authors.lastname: Coles
authors.forename: T D
authors.initials: TD
authors.lastname: Wilkinson
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D003198:Computer Simulation; D003720:Densitometry; D004735:Energy Transfer; D050866:Liquid Crystals / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D017785:Photons
chemical_list: D004396:Coloring Agents