| With the development of optoelectronic field and the smaller and smaller size of integrated electrical apparatus,the demand for micro-and nano-optoelectronic devices is increasing.As the key device of optical communication,micro-nano grating has important applications in the fields of spectrum,holographic projection and optical measurement.Ten kinds of micro-nano gratings with different structures and materials under different incident conditions are presented:（1）A beam splitter with Ag reflective metal under normal incidence is presented.The grating can achieve ±1st order dual-order uniform reflection under two polarizations,and its performance is studied by the rigorous coupled-wave analysis（RCWA）.（2）The transmissive grating under normal incidence with the zeroth order eliminated is described based on the structure of T-ridge grating.Most of the energy is diffracted to ±1st and ± 2nd orders by the beam splitter.It is found that the beam splitter has good uniformity by the rigorous coupled-wave analysis.Based on the finite element method（FEM）,the normalized electric field distribution of beam splitter is analyzed.（3）A four-channel reflective beam splitter based on T-type double-layer different dielectric grating is represented.Using the modal method,the effective refractive index of each mode can be calculated from the dispersion equation.,and the physical transmission mechanism of the grating is described clearly.The finite element method depicts the electromagnetic field intensity distribution,which can reflect the energy transfer in the grating more directly.（4）A polarization-selective bullet-alike reflective grating is described under second Bragg incidence.The single-order high efficiency of TE polarization and the double-order uniform beam splitting of TM polarization are realized by the grating.The diffraction property is analyzed by the finite element method.（5）One-port reflector for transverse-electric（TE）polarization and two-port beam splitter for transverse-magnetic（TM）polarization was presented by T-shaped polarization-selective grating.In addition,the normalized electromagnetic field are obtained by FEM.Finally,the incident condition and process tolerances are analyzed,and the range of structural parameters that meets the good reflection efficiency is found.（6）A stacked terahertz beam splitter with a frequency of 2.52 THz is proposed for polarization selection.In addition,the energy distribution of terahertz wave in the grating can be clearly seen by using finite element method to simulate the normalized electric field.Finally,the tolerance of the proposed polarization selective grating is simulated and tested,and it is found that the grating has a wide band and is insensitive to the incident angle.（7）A V-ridge transmission grating as a polarizer under second Bragg incidence is proposed.The high diffraction efficiency of-2nd order under TE polarization and 0th order under TM polarization is realized.It is found that the grating has high efficiency and extinction ratio by finite element method.（8）A double-layer reflection bullet-alike reflection grating is proposed,which can diffract the TE-and TM-polarized light to-2nd order.The optical field distribution of the grating is obtained by FEM,and the grating has good tolerance.（9）Two kinds of multi-layer narrow-band absorbers under normal incidence are proposed.The field distribution is obtained by FEM,and the effect of structural parameters on the absorption efficiency is analyzed.（10）A narrow-band absorber with trapezoidal grating ridge is presented.The absorption efficiency is calculated by FEM and verified by the finite-difference time-domain method,and the diffraction efficiencies calculated by the two methods are consistent.Finally,how each grating parameter affects the absorption efficiency through the influence of the light field distribution is analyzed. |
