With The Random Laser Oscillation Characteristics And Numerical Analysis Of The Micro-cavity Structure

Random laser has become a promising new laser because of its unique structure and good optics characteristics,for example,using random laser's small size,it can be served as light source in new integrated device;Using its multi-directional outputing light,it can be used to display,code the document and measure the distribution of flowing field;Using its unidirectional outputting light,it can be made optical diode. Different occasions have different optical properties requirements for random lasers , but stimulating random laser needs a high pump intensity, this enormously hinders its application. In order to improve the optical properties of random laser and reduce its threshold,people proposed the methods of pumping by double photons,controlling temperature,controlling the randomness of partial random medium,having external mirror and so on, these methods reduce random laser's threshold from different angles, and the last of these ways reduces the threshold of the greatest.One hotspot in the research work of random laser is the study about the influence of resonance characteristics made by external mirror, which mainly focuses on experimental research,including reducing the threshold,emergencing output light intensity and unidirection by microcavity. This article has conducted the research of the random laser's resonant characteristics mainly from the fundamental research and simulation.The article first theoretically analyzes the principle that microcavity reduces threshold,changes resonant modes of output light and enhances unidirection of the random laser. Then study the structure parameters of different microcavity by transfer matrix. Based on the theory of Maxwell equations and the rate equations, analyze the principle that microcavity reduces the threshold by FDTD method: Changing the confined position,reducing relaxation time and increasing reversing particles, also simultaneously study the influences of the threshold and output light modes by different microcavities and random intensity of random medium.The resultes not only provide certain evidences for selecting parameters of photonic crystal microcavity, but also deepen the understanding of reducing random laser's threshold,enhancing light enlarged by microcavity,provide important evidences for reducing threshold of random laser,improving wave modes and optimizing random lasers and microcavities at different situation.