Lasing Characteristics In Perovskite Microcavity

Lead halide perovskites,as emerging photovoltaic materials,possess outstanding material properties,such as high optical absorption coefficient,long carrier diffusion length,long carrier lifetime and low defect density,etc.Very recently,the power conversion efficiency(PCE)of lead halide perovskite based solar cells has been increased to 22.7%,approaching that of crystalline silicon based solar cells.In addition to the excellent photovoltaic properties,as direct bandgap semiconductors,lead halide perovskites also show low cost,solution synthesis,high photoluminescence quantum yield and tunable emission wavelengths,bringing new hopes to realize electrically driven and low-cost semiconductor lasers.In the past few years,versatile lead halide perovskites based micro-and nanolasers with different resonant cavities,pump energy,pump pulse width and fabrication techniques have been proposed and experimentally demonstrated.However,up to now,studies on the perovskite lasers have been limited to different kinds of cavities,perovskites and pump wavelengths,researches on perovskite lasing performance and practical applications have rarely been reported.Therefore,this thesis focuses on the basic properties of perovskite lasers,such as mode numbers,quality factors,emission directions,mode interactions as well as practical applications,etc.The researches are to provide theoretical and experimental references to realize continuous-wave and even electrically driven perovskite lasers at room temperature.And the thesis is organized as follows.(1)The effect of substrate on resonant modes in microcavities has been investigated.By introducing leaky loss into one end of perovskite microwire,FabryPerot(FP)mode oscillating in the axial direction is suppressed,and then lasing emission based on whispering gallery(WG)mode in the cross section of perovskite microwire is observed for the first time.By reducing the scattering and radiative loss,lasing emission with high quality factor has been realized.By changing the pump position and pump spot size,the mode competition and mode switching between transverse WG mode and axial FP mode is investigated.(2)The effect of spatially periodic leaky loss on resonant modes in microcavities has been investigated.By transferring a perovskite microrod onto a silicon grating,an easy,high-density and uniform nanolaser array has been demonstrated.(3)Mode coupling between two perovskite microwires has been investigated.By cutting a perovskite microwire into two parts and then moving them together,photonic molecule laser is realized under optical pumping.(4)The effect of waveguide on emission direction of perovskite microdisk is investigated.Waveguide connected perovskite microdisk is synthesized via controlling the synthesis condition,and then unidirectional lasing emission has been demonstrated.In summary,the researches in this thesis improves the perovskite lasing performances significantly,providing theoretical and experimental supports to electrically driven perovskite lasers,and expends new room to the mode control in microcavities.