The Study On The Improvement Of Linewidth Of Phonon Laser With Phonon Crystal Filter

Acoustic frequency generated from phonon laser is widely used at THz waveband and hasarisen extensive research recently. However this laser still hassome disadvantages, for example, theline width of sound waves which emitted from THz Stark Ladder superlattice phonon laser is toolarge to meet the actual demand. A method which applies phononic crystal to phonon laser aimed toimprove the line width of phonon laser is proposed in this paper.A new type of phononic crystal filter is proposed in this paper, the filter consists oftwo-dimensional square lattice phononic crystal, point defects and line defects. To design theoptimum filter with good performance, COMSOL Software based on the Finite Element Method(FEM) is firstly used to simulate the material, structure of the lattice and media column of thephononic crystal filter. Then, the best component structure with the maximum bandgap is selectedand point defect, line defect are taken into consideration in the designing of phononic crystal filter.The size and the location of the media column is obtained after majorization. Finally the optimizedparameter setting of the filter is obtained by analyzing the influence of the location and size of thepoint defect on the performance of the filter.On the basis of the direct-coupled phononic crystal filter, the designed phononic crystal isapplied into the phonon laser to improve the line width of the sound wave. The simulation resultsshow that when matrix material is mercury, media column material is water, the shape of the latticeis square, the media column is circular, the lattice constant of the phonon crystal is1.34434nm, thefilling rate of complete lattice media column is0.3847, the filling rate of at line defect is0.0177andthe filling rate of media column at point defects is0.0228, the line width of sound wave is improvedfrom0.52GHz to0.95GHz and the transmittance is92%. The performance of the phonon laser isimproved.