title: Small divergence substrate emitting quantum cascade laser by subwavelength metallic grating.
abstract: Metallic periodic structure in subwavelength scale offers an exciting way to couple light into surface plasmons (SPs), thus manipulating the properties of near-field optics. We show that subwavelength metallic grating (SMG) defined on the substrate side of substrate emitting quantum cascade lasers enables far-field improvement in mid-infrared spectrum. The SMG is designed to tailor the interaction of SPs with single mode transverse magnetic light. The experiment results are in good agreement with the simulated model. A far-field full width at half maximum (FWHM) divergence angle of 3.9 ° in the direction perpendicular to the laser waveguide layers is obtained, improved by a factor of 8.5 compared with traditional surface emitting device.
authors.forename: Dan-Yang
authors.initials: DY
authors.lastname: Yao
authors.forename: Jin-Chuan
authors.initials: JC
authors.lastname: Zhang
authors.forename: Ying-Hui
authors.initials: YH
authors.lastname: Liu
authors.forename: Ning
authors.initials: N
authors.lastname: Zhuo
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Jia
authors.forename: Feng-Qi
authors.initials: FQ
authors.lastname: Liu
authors.forename: Zhan-Guo
authors.initials: ZG
authors.lastname: Wang