The Research On Near-Infrared Nanowire Plasmonic Lasers

Semiconductor nanowires have significant potential applications in miniaturized lasers.However,further reduction of the dimension for photonic mode nanowire lasers has encountered the bottleneck due to the optical diffraction limit.Surface plasmon polaritons(SPP)offer the possibility of breaking through the diffraction limit as they allow compact storage of optical field at subwavelength scale.Hence constructing a SPP nanowire laser by combing a nanowire with SPP is a feasible path to achieve a deep subwavelength laser breaking through the diffraction limit.In this thesis,theoretical research on plasmonic III-V nanowire lasers is carried out.The main contributions are as follows:(1)The threshold characteristics of plasmonic GaAs nanowire lasers are investigated theoretically by using 3D finite-difference time-domain(FDTD)method.The results show that the higher order SPP mode exhibits lower propagation losses compared to fundamental mode due to the poor confinement,and is more easily to lase.While the hybrid plasmonic mode alleviates the influence of metal on its guiding properties by storing electromagnetic energy in the gap,and is more easily to lase at small diameter compared to the higher order mode.(2)A nanolaser based on AlGaAs/GaAs radial multi-quantum-well(MQW)structure is designed and simulated,and the modal distributions and lasing characteristics of the photonic and hybrid plasmonic lasers are studied comparatively.The results show that the photonic laser is easier to lase at large diameter,while the hybrid plasmonic laser is capable of lasing at smaller diameters beyond the optical diffraction limit,with the lowest threshold gain of 788 cm-1 at the diameter of 130 nm.The cutoff diameter of hybrid plasmonic laser is 80 nm,half that of the photonic lasers.Moreover,due to the distinct Purcell effect,the spontaneous emission intensity of hybrid plasmonic lasers is more than 8 times that of the photonic lasers.(3)The lasing characteristics of hybrid plasmonic AlGaAs/GaAs nano wire radial MQW lasers and GaAs/AlGaAs nanowire core-shell lasers are studied comparatively.The results show that the hybrid plasmonic nanowire MQW lasers exhibit distinct lower threshold gain and higher Purcell factor over a wide range of diameter,and the threshold is much lower over a broad wavelength range,in comparison with nanowire core-shell lasers.