Research On The Performance Of Microcavity Lasers On Fiber Facet

With the rapid development of micro-nano optics,the demand for miniaturization and integration of microcavity lasers is increasing.Microcavity lasers consist of a gain medium and a microresonator,where the size of the microresonator is on the micron/submicron scale.It has the following characteristics:low threshold,low power consumption,fast response,high quality factor（Q value）.In addition,such devices are small in size and easy to integrate,for example,they can be integrated into the fiber end face or side wall.Based on the above characteristics,microcavity lasers have potential applications in speckle-free imaging,optical sensing,medical detection,neural networks,and optical communications.In recent years,research groups at home and abroad have conducted extensive research on microcavity lasers,including Fabry-Perot microcavities,distributed feedback microcavities,random microcavities,and whispering gallery microcavities.In this paper,we mainly study two types of microcavity lasers:random lasers and whispering gallery microcavity lasers.Considering that the optical fiber has the characteristics of flexibility,high orientation,low loss,low cost,and easy docking with other equipment,the integration of the microcavity laser with the optical fiber can make the optical system more compact.Such devices can be conveniently used for speckle-free imaging,optical sensing and medical detection.Based on this,this paper is devoted to the research of fiber end-face random laser/whispering gallery laser.Through the design and optimization of the gain medium and the micro-resonator structure,a micro-cavity laser was successfully fabricated on the fiber end face,and its fluorescence/laser emission characteristics were studied.The main research contents of this paper are as follows:1.Design,preparation and optimization of random fiber end-face lasers.Through the selection of the gain medium and the optimization of the preparation method,the random laser emission from the fiber end face is realized,and it is used as the light source to realize the high-quality speckle-free imaging.（1）dip coating method.Through the preliminary exploration of gain materials and preparation methods,organic-inorganic hybrid perovskite（MAPb Br3）was selected as the gain medium,and a random laser was successfully fabricated on the fiber end face by a simple and low-cost"two-step dip-coating method".Under the condition of optical pumping,random laser emission from the fiber end face is realized.The threshold of the laser device is32.3μJ/cm2,the laser linewidth is 4 nm,the divergence angle is less than 60°,and the spatial coherence is 0.6279.Using the laser device as the light source,the effects and characteristics of random lasers for speckle-free imaging were studied.（2）Inkjet printing method.As an improvement plan,we have studied the controllability of the preparation method,using nano-deposition technology（inkjet printing）,using MAPb Br₃ solution as the ink,printing on the fiber end face,and realizing the preparation of random laser.Based on the good controllability of the inkjet printing method,the customization of the position and size of the microcavity can be achieved.We sequentially printed different gain media（MAPb Br₃ and MAPb I₃）on the fiber end face,studied the design and fabrication of the two-color random laser at the fiber end face,and are further optimizing the parameters in order to obtain the laser emission.2.Design,fabrication and optimization of fiber end-face whispering gallery microcavity laser.Using the inkjet printing method,a disc structure with smooth edges can be realized,and this type of disc structure can be used as a whispering gallery microcavity to realize laser emission.We selected Cd Se/Cd S/Zn S red quantum dots as gain medium,and by adjusting the experimental parameters,a disc structure with controllable size can be prepared on the fiber end face.Under the condition of optical pumping,the laser emission of the whispering gallery microcavity on the fiber end face is realized.Further sensing experiments will be carried out in the future.