Study On Optical Characteristics Of Subwavelength Optical Elements

Subwavelength optical element is a developing branch of micro-optics. Subwavelength optical elements have many optical characteristics, such as anti-reflective, polarizing, filter and so on. It makes the optical instrument systems to miniaturization, integration, low cost. Based on the effect medium theory, the anti-reflective and polarization property of the subwavelength optical elements have been analyzed. Subwavelength antireflective optical elements and polarization-control components have been designed. The diffraction efficiency of blazed binary subwavelength diffractive elements at oblique incident and over a broad wavelength range has been investigated.Based on the effective medium theory and the thin film theory, a subwavelength anti-reflective optical element has been designed. The transmission as a function of the micro structures parameters and the incident angles has been analyzed. We present an optimal design to maximum the polychromatic integral transmission efficiency (PITE) of the subwavelength optical element for the wavelength band0.3um-1.2μm.With careful design optimization, for TE and TM polarization state, the PITEs are98.8802%and98.8805%.Subwavelength waveplates and subwavelength polarization beam splitters have been analyzed and designed based on the form birefringence. For sub-wavelength wave-plates, we proposed using high-index materials as the substrate medium to reduce the fabrication constraints and combing with coating and etching. The results show that the technique not only improves the transmission of the TE and TM polarized light, but also reduces the difference of transmission between them. For subwavelength polarization beam splitters, the extinction ratio as a function of the structures parameters and incident angle has been presented. A high extinction ratio in transmission (>55.71dB) over abroad interval of angles of incidence ([-60",60"]) is achieved.Blazed binary subwavelength diffractive optical elements etched into a material of high refractive index have been designed based on the diffraction theory and the effective medium theory. This approach not only reduces fabrication constrains, but also increases the diffraction efficiency and obtains the phase delay of2π. The blazed binary subwavelength diffractive optical elements can obtain higher diffraction efficiency at the oblique incident and over the broad wavelength.