Polarizing beam splitter is designed with a broadband and wide range of incident angle. Polarizing beam splitter designed here is a kind of double periodic subwavelength medium-metal grating, which consisted of silicon dioxide as the substrate, magnesium fluoride (MgF2) as medium material and silver for the grid lines. It has the polarization splitting function of TE reflection and TM transmission. Based on the rigorous coupled-wave analysis(RCWA) and the continuous optimization of the structure parameters, the polarization beam splitter has high polarization conversion efficiency, high extinction ratio and a wide tolerance of incident angle in the near infrared band (1μm − 3μm) .The simulation results show that the reflection efficiency of TE polarized light and the transmission efficiency of TM polarized light are both higher than 96%, and the reflection extinction ratio and transmission extinction ratio are greater than 17dB and 28dB respectively. When the incident angle of incident light is from -80° to 80°, the reflection efficiency of TE polarized light is over 96%; when the incident angle is from -40°to 40°, the transmission efficiency of TM polarized light is over 90%. The reflection extinction ratio exceeds 17dB, and the transmission extinction ratio exceeds 35dB in the incident wavelength of 1550nm.The designed polarizing beam splitter is expected to be used in optical communication, optical storage, optical sensing and other fields for light modulation and control.
A nanoslit array is introduced on the silicon waveguide, and the phase difference is controlled by the slit width to satisfy the function of the focusing lens. If keep the designed width and depth of the slit in accordance with the focusing effect unchanged, when the incident wavelength changes, the focal position must change accordingly, and the dispersion effect is significant. In order to achieve the achromatic effect, the refractive index of the surrounding medium is changed while changing the wavelength. Finally, the refractive index of the surrounding medium which can keep the focal length constant at the wavelength of 1550-1950nm is obtained, and the equation that the change of the refractive index and the wavelength of the medium makes the focal length constant is obtained. The achromatic effect can be effectively achieved, and applications range of achromatic metalens from imaging in optical communications to telescopes in the astronomical field.
We introduce phase-change material Ge2Sb2Te5 (GST) into metal–insulator–metal (MIM) waveguide systems to realize chipscale plasmonic modulators and switches in the telecommunication band. Benefitting from the high contrast of optical properties between amorphous and crystalline GST, the three proposed structures can act as reconfigurable and nonvolatile modulators and switches with excellent modulation depth 14 dB and fast response time in subnanosecond while possessing small footprints, simple frameworks, and easy fabrication. We provide solutions to design active devices in MIM waveguide systems and can find potential applications in more compact all-optical circuits for information processing and storage.
Metamaterials have attracted a lot of attention in the past decade, because of its remarkable properties in electronics and photonics. Recently, a new kind of two-dimensional metamaterial named metasurface have led the research front. Metasurfaces show up excellent optical properties by patterning planar nanostructures. Novel optical phenomena based on graphene include ultra-thin focusing, anomalous reflection or refraction strong spin-orbit and so on. In this work, we have designed a novel infrared light polarized beam splitter by combining the 2D array of graphene with a subwavelength-thickness optical cavity, which demonstrated great splitting effect in infrared wavelength. Our demonstration pave a novel way for the infrared light polarized beam splitting.