Design and characterization of dielectric subwavelength focusing lens with polarization dependence
| Autor: | Yeshaiahu Fainman, Lin Pang, Sung W. Kim |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Diffraction
Wavefront Microlens Materials science business.industry Aperture Physics::Optics 02 engineering and technology Dielectric 01 natural sciences law.invention Lens (optics) 020210 optoelectronics & photonics Optics Achromatic lens law 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Optoelectronics 010306 general physics business Refractive index |
| Zdroj: | SPIE Proceedings. |
| ISSN: | 0277-786X |
| DOI: | 10.1117/12.2220449 |
| Popis: | We introduce and develop design, fabrication and characterization methodology for engineering the effective refractive index of a composite dielectric planar surface created by controlling the density of deeply subwavelength low index nanoholes (e.g., air) in a high index dielectric layer (e.g., Si). The nanoscale properties of a composite dielectric layer allows for full control of the optical wavefront phase by designing arbitrary space-variant refractive index profiles. We present the composite dielectric metasurface microlens exploiting symmetric design to achieve polarization invariant impulse response, and use asymmetric design to demonstrate polarization sensitive impulse response of the lens. This composite dielectric layers lenses were fabricated by patterning nanohole distributions on a dielectric surface and etching to submicron depths. Our dielectric microlens with asymmetric distribution of n eff (n eff x ≠ n eff y ) demonstrates a graded index lens with polarization dependent focusing with of 32um and 22 um for linearly x- and y-polarized light, respectively operating at a wavelength of λ = 1550nm. We also show numerically and demonstrate experimentally achromatic performance of the devices operating in the wavelength range of 1500nm - 1900nm with FWHM of the focal spots of about 4um. Namely, we have constructed a graded index lens that can overcome diffraction effects even when aperture/wavelength (D/λ) is smaller than 40. The demonstrated novel approach to engineer dielectric composite nanosurfaces has the potential to realize arbitrary phase functions with minimal insertion loss, submicron thickness and miniaturization to reduce element size and weight, and may have a significant impact on numerous miniature imaging systems applications. |
| Databáze: | OpenAIRE |
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