Research On The Characterisitics Of Graphene Photonic Crytal Micro-cavity And Waveguide

An optical micro-cavity can also be called an optical resonator,and the light of a specific frequency can be limited by an optical resonator when a defect occurs in a periodic medium.The size of the optical micro-cavity is very small,usually from a few microns to a few hundred microns,which can meet the requirements of integrated optics for the miniaturization and integration of optical devices;At the same time,the optical micro-cavity has very high quality factor and small mode volume,and can be applied to low threshold laser and optical sensor.And the optical micro-cavity is also being paid more and more attention because of its advantages of easy to make and good optical performance.In this paper,two kinds of optical micro-cavities are designed,one is one dimensional the tapered ring graphene photonic crystal nanobeam micro-cavity of one dimensional,the other is the two-dimensional hybrid graphene/surface plasmon micro-cavity of two dimensional.Based on the SiO₂,a tapered ring graphene photonic crystal waveguide with high locality and low loss is constructed on the silicon layer.This waveguide has an obvious TM mode band gap.Due to the existence of the tapered ring,the nanobeam cavity is formed in the waveguide.The energy band characteristic of the micro-cavity is simulated using the three-dimensional finite-difference time-domain method.The influence of the parameters on the micro-cavity characteristics is discussed,such as number of air rings in tapered section and mirror section,the radius of inner and outer air rings and nanobeam width.The characteristic parameters for the structure are determined.The result shows that the micro-cavity structure has a higher quality factor and a very small mode volume in the 1550 nm communication band.Compared to the conventional micro-cavity,this micro-cavity has smaller transmission loss and better mode confinement.At the same time,the influence of mode mismatch can be reduced.The radiation loss and dissipation loss of the micro-cavity can be effectively reduced.The micro-cavity can be applied to electro-optic modulator or tunable laser.The electro-optic modulation can be realized by changing the Fermi level of graphene with different applied voltage.The micro-cavity of mixed graphene and surface plasmon is based on the photonic crystal-graphene-photonic crystal model,introducing a defect in the center of the two photonic crystal layers,forming a defect cavity.By changing the structural parameters of the micro-cavity,the energy band characteristics,quality factor and mode volume of the micro-cavity structure are analyzed by the three-dimensional finite-difference time-domain method.And the field intensity distribution of this micro-cavity structure is obtained.It is proved that the proposed micro-cavity structure has obvious photonic band gap.The influence of the radius of the air hole around the defect and the medium with different refractive index in the air hole around the defect on the structure characteristics of the micro-cavity is studied and analyzed.The micro-cavity structure has a very small mode volume of sub-wavelength scale in the 1550 nm communication band.The value of Q/V is up to 29937.5??/n?-3.The micro-cavity structure has good electrothermal conductivity.It provided a new design idea and foundation for the fabrication of optical devices such as high-power lasers.