Numerical Simulation And Experimental Study On Random Lasing Emission Properties

Random laser is a novel and unique laser, which is different from conventional lasers. In conventional lasers, the optical cavity determines the laser's pattern and direction. While in random lasers, the multiple light scattering in random systems determine the properties of the emission, including the model, threshold value, direction of laser, and so on. Ramdom lasing phenomeon are studied widely not only for their interesting physical properties, but also for their importance in future applications. In this master's thesis, we carry out our numerical simulation and experimental study on short-pulse pumping neodymium glass powder samples as follows:We simulated numerically short-pulse pumping the one-dimensional random gain medium by the finite difference time domain method and get the following conclusions: For a fixed random sample, the pumping intensity will affect the emission properties. The configuration of the random medium has much influence on the emission in the time domain and frequency domain.The neodymium glass powder was prepared by grinding the crushed bulk samples. Binding, pressing, and low temperature sintering were carried out to fabricate the samples which have different transport mean free path based on the neodymium glass powder. We build an experimental platform and test the emission spectrum of these samples under pumping. Some special optical detection circuits were designed to detect the emission pulse of the samples in temporal regime. We also analyze the reason that the emission spectrum of the neodymium glass powder samples does not achieve the desired result and propose some solutions.We set up an experimental platform for coherent backscattering measurements. Using the coherent backscattering technique, we have measured the transport mean free path lengths for our neodymium glass powder bindings and the value is 8.8 micrometer. The result shows that we need further grinding neodymium glass powder. We also give the improvement program of this experiment.