title: Direct Bandgap Light Emission from Strained Germanium Nanowires Coupled with High-Q Nanophotonic Cavities.
abstract: A silicon-compatible light source is the final missing piece for completing high-speed, low-power on-chip optical interconnects. In this paper, we present a germanium nanowire light emitter that encompasses all the aspects of potential low-threshold lasers: highly strained germanium gain medium, strain-induced pseudoheterostructure, and high-Q nanophotonic cavity. Our nanowire structure presents greatly enhanced photoluminescence into cavity modes with measured quality factors of up to 2000. By varying the dimensions of the germanium nanowire, we tune the emission wavelength over more than 400 nm with a single lithography step. We find reduced optical loss in optical cavities formed with germanium under high (>2.3%) tensile strain. Our compact, high-strain cavities open up new possibilities for low-threshold germanium-based lasers for on-chip optical interconnects.
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Jan
authors.initials: J
authors.lastname: Petykiewicz
authors.affiliation: Department of Electronic Engineering, Inha University , Incheon 402-751, South Korea.
authors.forename: Donguk
authors.initials: D
authors.lastname: Nam
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: David S
authors.initials: DS
authors.lastname: Sukhdeo
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Shashank
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Sonia
authors.initials: S
authors.lastname: Buckley
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Piggott
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Jelena
authors.initials: J
authors.lastname: Vučković
authors.affiliation: Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Saraswat
keywords: Germanium; group IV; nanophotonics; optical interconnects; pseudoheterostructure; strain