Manipulation of random laser by the bandgap in three-dimensional SiO2 photonic crystals

Abstract

Photonic crystals (PCs) are artificial structures with different dielectric constants that are arranged periodically in space and can control the propagation of electromagnetic waves of specific frequencies. The photonic bandgap can tune the photon state density, which is beneficial for the generation of random lasers (RLs). In this paper, a thin film of PMMA-doped DCJTB is spun-coated on a silicon dioxide (SiO2)PC to produce an RL. The PC is fabricated by a convenient dip-coating method with variable PBGs by changing the diameter of SiO2 nanospheres. By changing the position of the PBG gap, the RL emission peak can be effectively manipulated with an emission wavelength of up to 16 nm. By adding Au nanoparticles, the lasing performance is improved due to the surface plasmon resonance effect and strong photon scattering, where the emission intensity is increased by 191.9 %, and the threshold is decreased by 37.8 %. The imaging results show that the RL has low spatial coherence, which has a good application in speckle-free imaging. This study provides an effective method to produce a low threshold, high-quality RL with convenient manipulation of lasing properties, which opens the door for expanding its application in optoelectronic devices and speckle-free imaging.