8 May 2018 Wide bandwidth, achromatic, planar silicon lenses for long-wave infrared imaging
Author Affiliations +
Long Wave Infrared (LWIR) lenses require performance over a wide wavelength range of 7-14 μacceptance and efficient transmission. The subwavelength structures in the lens designs should conform with the capabilities of the current state of the art Deep Reactive Ion Etching (DRIE). The result of etching high aspect ratio 78:1 features in silicon is presented. The subwavelength structures are model using Finite-Difference Time-Domain (FDTD) simulation and a region of strong positive dispersion has been identified. By using the strong positive dispersion with periodic index steps, an achromatic focusing surface can be fabricated in a single etch step. Using custom modeling software, the propagation of light in the range 7-13 μm is performed on the achromatic surfaces. The surfaces have a very efficiency based on the results from the (FDTD) simulation. The design and performance of chromatic lenses are presented. The lenses enable interesting imaging designs for LWIR imaging applications. Results of testing the achromatic properties of silicon structures is presented.
Conference Presentation
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Gregory Kintz, Gregory Kintz, Phil Stephanou, Phil Stephanou, "Wide bandwidth, achromatic, planar silicon lenses for long-wave infrared imaging", Proc. SPIE 10627, Advanced Optics for Defense Applications: UV through LWIR III, 1062709 (8 May 2018); doi: 10.1117/12.2305039; https://doi.org/10.1117/12.2305039

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