title: Optical gain in single tensile-strained germanium photonic wire.
abstract: We have investigated the optical properties of tensile-strained germanium photonic wires. The photonic wires patterned by electron beam lithography (50 μm long, 1 μm wide and 500 nm thick) are obtained by growing a n-doped germanium film on a GaAs substrate. Tensile strain is transferred in the germanium layer using a Si₃N₄ stressor. Tensile strain around 0.4% achieved by the technique corresponds to an optical recombination of tensile-strained germanium involving light hole band around 1690 nm at room temperature. We show that the waveguided emission associated with a single tensile-strained germanium wire increases superlinearly as a function of the illuminated length. A 20% decrease of the spectral broadening is observed as the pump intensity is increased. All these features are signatures of optical gain. A 80 cm⁻¹ modal optical gain is derived from the variable strip length method. This value is accounted for by the calculated gain material value using a 30 band k · p formalism. These germanium wires represent potential building blocks for integration of nanoscale optical sources on silicon.
authors.affiliation: Institut d'Electronique Fondamentale, CNRS-Univ. Paris-Sud 11, Orsay, France.
authors.forename: M
authors.initials: M
authors.lastname: de Kersauson
authors.forename: M
authors.initials: M
authors.lastname: El Kurdi
authors.forename: S
authors.initials: S
authors.lastname: David
authors.forename: X
authors.initials: X
authors.lastname: Checoury
authors.forename: G
authors.initials: G
authors.lastname: Fishman
authors.forename: S
authors.initials: S
authors.lastname: Sauvage
authors.forename: R
authors.initials: R
authors.lastname: Jakomin
authors.forename: G
authors.initials: G
authors.lastname: Beaudoin
authors.forename: I
authors.initials: I
authors.lastname: Sagnes
authors.forename: P
authors.initials: P
authors.lastname: Boucaud