Researches On Bound States In The Continuum Of Periodic Rectangular Micro-nano Hole Arrays And Its Regulation

Bound states in the continuum(BIC)are waves that remain localized although they coexist with a continuous spectrum of radiating waves that can carry energy away.Although BIC was initially proposed in the context of quantum mechanics,they are a general wave phenomenon and have since been identified exist in various fields of physics,and has been gradually verified theoretically and experimentally.The research of BIC is of great significance to the development of photonic integration,communication and defense technology.In this paper,based on the previous research on BIC,using the Stanford Stratified Structure Solver(S4)software package,the finite-difference time-domain(FDTD)simulation and the coupled mode theory(CMT)and other methods,the photonic crystal slabs has Various effects have been studied on the BIC state effect of different micro-nanohole structures.The research contents are as follows:1)The BIC characteristics and control of the micro-nano rectangular double-hole array structure are analyzed.It is found that when the incident light is polarized along the x-axis direction,at-ΓBIC can only appear in the symmetric structure along the y-axis,but there cann’t appear in asymmetry structure or symmetry structure along the x-axis.The off-ΓBIC exists in both symmetric and asymmetric structures,and its quality factor Q can exceed 10~6.In addition,by changing the refractive index of the surrounding dielectric,it was found that the resonance wavelength is more sensitive to the environment than the metal or traditional dielectric structure;2)The BIC characteristics and regulation of the micro-nano annular rectangular double-hole array structure are discussed,and a symmetric annular double-hole is found There are two at-ΓBICs in the structure.When the two inner rectangles are moved symmetrically along the x-axis or synchronously up and down along the y-axis,the structure is still symmetrical.At this time,more than one at-ΓBIC can still be obtained.In the asymmetric annular rectangular double-hole structure,and when the inner rectangles is moved up and down,the at-ΓBIC of the low-order mode does not exist,and only the at-ΓBIC of the high-order mode can exist in a few cases.Whether it is in a symmetrical structure or in an asymmetrical structure,off-ΓBIC can exist,and the angle and wavelength of BIC can be changed by adjusting the position of the inner rectangle;3)Explored the BIC and its regulation of micro-nano rectangular three-hole array structure,found that there are three at-ΓBIC when the symmetry plane(y-axis)of the micro-nano rectangular three-hole array structure is perpendicular to the oscillation direction of the incident light(x-axis).When the length of hole A is changed,the structure still maintains symmetry along the y-axis,and there are three at-ΓBICs.When the length of hole B is changed to break the symmetry of the structure along the y-axis,the at-ΓBIC no longer appears.When changing the position of hole A or the positions of two holes of B and C,as long as the structure still has symmetry along the y axis,at-ΓBIC can appear.For off-ΓBICs,they can appear in both symmetrical and asymmetrical structures,but the position where they appear will vary with the structural factor.When the length of the A hole is changed,the center wavelength and incident angle of the off-ΓBIC gradually increases with the decrease of the length of the A hole.When the length of the B hole is changed,the center wavelength and incident angle of the off-ΓBIC will gradually increase as the length of the B hole decreases.When the hole A is moved up and down along the y-axis direction to change its position,the incident angle of the off-ΓBIC remains unchanged,indicating that the position of the A hole along the y-axis direction has no effect on the off-ΓBIC.