带有高折射率介质层的金属光栅偏振器特性的研究

Research on the Characteristics of Subwavelength Metal Grating Polarizers with a High Refractive-Index Dielectric Layer

研究了一种亚波长金属光栅偏振器在可见光波段的透射与消光特性。与传统亚波长光栅偏振器不同的是,通过在基底和光栅之间增加一层高折射率介质薄膜,提高了TM偏振光透射率和消光比。利用严格耦合波分析法(RCWA),模拟了高折射率介质层厚度、光栅占宽比对透射率和消光比的影响。计算结果表明,在整个可见光波段,合适的介质层厚度可使透射更加均匀并且当入射角在0～60°变化时,TM偏振光的透射率和消光比仍可分别达到79%和50 dB。这种带有高折射率介质层的亚波长金属光栅偏振器结构紧凑,性能优良,特别适合作为液晶平板显示中的偏振分光器件。

Transmission and extinction characteristics of a novel double-layer sub wavelength metal grating polarizer at visible region are investigated theoretically.The difference between the polarizer proposed and conventional lies in that the high refractive index dielectric layer is inserted between the substrate and grating,which icrease the transmissivity and extinction ratios.By using rigorous couple-wave analysis（RCWA）,the transmissivity and extinction ratios of transverse-magnetic wave（TM） polarization are analyzed as a function of the thickness of the high refractive index dielectric layer and the duty cycle.Simulation results show that the transmissivity is more uniform compared with that of the conventional type in visible region.When the incident angle range is 0～60°,the TM transmissvity is still about 79%and the extinction ratios is higher than 50 dB.The polarizers is very compact and suitable for backlight unit used in liquid crystal devices.