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
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.
