CAJ | 학술논문

用平面波展开法研究了内介质柱截面为长方形的三角晶格空气环型光子晶体的完全带隙特性.通过调节内介质柱的大小、介电常数、旋转角度以及空气环外半径对完全带隙的影响,找到了一组可以获得大带隙二维光子晶体结构的最佳参数.经优化后得到禁带宽度Δω=0.082(2πca~(-1)) (其中a为晶格常数,c为光速),中心频率ω_0=0.401(2πca~(-1)),完全带隙宽度与中心频率的比值达到了20.4%,该结果比圆形内介质柱截面空气环结构的完全带隙大,比普通的空气孔结构的完全带隙增大了37%.
용평면파전개법연구료내개질주절면위장방형적삼각정격공기배형광자정체적완전대극특성.통과조절내개질주적대소、개전상수、선전각도이급공기배외반경대완전대극적영향,조도료일조가이획득대대극이유광자정체결구적최가삼수.경우화후득도금대관도Δω=0.082(2πca~(-1)) (기중a위정격상수,c위광속),중심빈솔ω_0=0.401(2πca~(-1)),완전대극관도여중심빈솔적비치체도료20.4%,해결과비원형내개질주절면공기배결구적완전대극대,비보통적공기공결구적완전대극증대료37%.
Plane wave expansion method is employed to study the characteristic of the photonic band gap (PBG) structure of two-dimensional photonic crystal consisting of a triangular lattice with ring-shaped air holes which inner-dielectric cylinders are rectangular. The optimal samples that possess the largest gap-mid gap ratio are obtained by scanning the four parameters (size, dielectric constant, rotating angle of inner-dielectric cylinders and outside radius of air ring). It is showed that when the dielectric constant of inner-dielectric cylinders is the same as the dielectric constant of background ε_1=ε_2=16, the side-lengths of rectangular inner-dielectric cylinders have values of L_1=0.37a,L_2=0.19a respectively, inner-dielectric cylinders are rotated by 5° and the values of outside radius of air ring is 0.46a, a much larger complete band gap Δω=0.082(2πca~(-1)) (where α is lattice constant, c is light speed) is found at a mid-gap frequency ω0=0.401(2πca~(-1)),with Δω/ω_0=20.4%. Comparing with the standard annular photonic crystal, the photonic band gaps of new structure, of which inner-dielectric cylinders are rectangular shapes, are wider. Comparison of the calculated results and original lattice (circular air hole triangular array in dielectric background) reveals that the photonic band gap is considerably enhanced in size for annular structure in triangular lattice.