One of the most exciting breakthroughs in physics is the concept of topology that was recently introduced to photonics,achieving robust functionalities,as manifested in the recently demonstrated topological lasers.How...One of the most exciting breakthroughs in physics is the concept of topology that was recently introduced to photonics,achieving robust functionalities,as manifested in the recently demonstrated topological lasers.However,so far almost all attention was focused on lasing from topological edge states.Bulk bands that reflect the topological bulk-edge correspondence have been largely missed.Here,we demonstrate an electrically pumped topological bulk quantum cascade laser(QCL)operating in the terahertz(THz)frequency range.In addition to the band-inversion induced in-plane reflection due to topological nontrivial cavity surrounded by a trivial domain,we further illustrate the band edges of such topological bulk lasers are recognized as the bound states in the continuum(BiCs)due to their nonradiative characteristics and robust topological polarization charges in the momentum space.Therefore,the lasing modes show both in-plane and out-of-plane tight confinements in a compact laser cavity(lateral size~3λ_(laser)).Experimentally,we realize a miniaturized THz QCL that shows single-mode lasing with a side-mode suppression ratio(SMSR)around 20 dB.We also observe a cylindrical vector beam for the far-field emission,which is evidence for topological bulk BIC lasers.Our demonstration on miniaturization of single-mode beam-engineered THz lasers is promising for many applications including imaging,sensing,and communications.展开更多
We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of...We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of a THz quantum cascade laser. Multiple emission peaks are observed within a frequency range corresponding to the bandgap of a periodic counterpart with no disorder, indicating the presence of mode localization aided by Bragg scattering. Simulations and experimental measurements provide strong evidence for the spatial localization of the THz laser modes.展开更多
基金supported by the fundings from Singapore Ministry of Education(MOE),A*STAR Programmatic Funds,and the National Research Foundation Competitive Research Program that correspond the grants MOET2EP50120-0009,A18A7b0058,and NRF-CRP23-2019-0007,respectivelyL.L A.G.D.,and E.H.L.acknowledge founding support from the EPSRC(UK)Hyper Terahertz programme(EP/P021859/1)the Royal Society,and the Wolfson Foundation.Y.K.acknowledges a founding support from the Australian Research Council(grant DP200101168).
文摘One of the most exciting breakthroughs in physics is the concept of topology that was recently introduced to photonics,achieving robust functionalities,as manifested in the recently demonstrated topological lasers.However,so far almost all attention was focused on lasing from topological edge states.Bulk bands that reflect the topological bulk-edge correspondence have been largely missed.Here,we demonstrate an electrically pumped topological bulk quantum cascade laser(QCL)operating in the terahertz(THz)frequency range.In addition to the band-inversion induced in-plane reflection due to topological nontrivial cavity surrounded by a trivial domain,we further illustrate the band edges of such topological bulk lasers are recognized as the bound states in the continuum(BiCs)due to their nonradiative characteristics and robust topological polarization charges in the momentum space.Therefore,the lasing modes show both in-plane and out-of-plane tight confinements in a compact laser cavity(lateral size~3λ_(laser)).Experimentally,we realize a miniaturized THz QCL that shows single-mode lasing with a side-mode suppression ratio(SMSR)around 20 dB.We also observe a cylindrical vector beam for the far-field emission,which is evidence for topological bulk BIC lasers.Our demonstration on miniaturization of single-mode beam-engineered THz lasers is promising for many applications including imaging,sensing,and communications.
基金Ministry of Education-Singapore(MOE)(MOE 2016-T2-1-128)Agency for Science,Technology and Research(A*STAR)(1426500050)+2 种基金National Research Foundation Singapore(NRF)(NRF-CRP18-2017-02)Engineering and Physical Sciences Research Council(EPSRC)(EP/P021859/1)Royal Society and Wolfson Foundation
文摘We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of a THz quantum cascade laser. Multiple emission peaks are observed within a frequency range corresponding to the bandgap of a periodic counterpart with no disorder, indicating the presence of mode localization aided by Bragg scattering. Simulations and experimental measurements provide strong evidence for the spatial localization of the THz laser modes.
