The Study Of The Random Laser In The Transverse Disordered Waveguide Array

Light scattering is a common physical phenomenon of nature,especially in optical waveguide.It has two sides in the optical waveguide: on the one hand,it can cause additional light loss;on the other hand,it can also play a useful role,such as forming random laser by the use of scattering in the waveguide with gain feedback.Random laser is a new type of laser,which relies on the light scattering to provide feedback and form a feedback loop to achieve laser excitation.Compared with the traditional laser,random laser has no traditional resonator,and contains advantages of a simple structure,low precision cavity,high degree of control freedom and so on.It has potential application value in areas such as medical,biological,light sensing,optical imaging and so on.This paper presents a novel random laser based on transverse disordered waveguide array,and studies its corresponding output characteristics.The proposed random laser is implemented in a cylindrical quasi-fiber waveguide structure by filling a quartz waveguide inside with waveguide structures such as single mode fibers,and filling it with laser dyes as gain medium in the quartz capillary.This design is helpful to reduce the random laser threshold and make output tunable.Also,structures of the scattering layer and those of the laser dye separate,which makes it more stable and reusable than the traditional random laser that can not separate the scattering medium and the laser dye.The details are as follows:First of all,a numerical simulation of the waveguide structure was performed: Using the FDTD numerical simulation method,the electric dipole is introduced into the structure as a light source and the output spectral characteristics in the waveguide are analyzed.The randomly distributed peaks observed from the spectral characteristics,which are correspond to different resonance modes.The electric field distributions corresponding to the resonant modes exhibit bright speckles in different regions,i.e.,photon localization effects are generated.Then,two different samples of the aforementioned random laser were fabricated under experimental conditions,in which the waveguide array of one sample was composed of non-corroded single-mode optical fibers,and the single-mode optical fibers in the other sample were subjected to etching treatment.By analyzing the spectral characteristics of the two samples,we found that the spectrum is similar to the WGM,and there is a certain degree of randomness.Finally,according to the numerical simulation and experiment,the power distribution characteristics in the localized spectrum range of the transverse disordered waveguide array are explored.By analyzing the power distribution of the simulated structures with three different degrees of chaos(0%,10%,and 20%),it is observed that WGM-like phenomena occur in the transverse disordered waveguide array and the distribution is random.At the same time,the impact of different degrees of chaos on power distribution was analyzed.It was found that the light intensity generated in the simulation structure increases with the increase in the degree of chaos.