The wave analysis of nature-inspired eye structures for infrared detectors

The dynamics of nature and the science of biomimicry can give humans insight for technologies to ease everyday life. The materials in nature have the desired properties such as durability, flexibility and lightness. Natural sight structures of small invertebrates, i.e. compound eyes of bees or flies, are perfectly designed to have enough visual information about their surroundings without overloading the brain with unnecessary image processing. Although these compound eyes are composed of small optical units, they can detect wide-angled electromagnetic waves, their reflection rate is lower and absorption rate is higher at the photoreceptor site. Mimicking such a natural imaging system in real word application will not be straightforward. Besides, high-resolution cases increase the overall cost of the detectors. The interaction between the human eye or other eye structures in nature and light is generally determined by the ray analysis. Light's wave property is not taken into consideration in these kinds of analysis, and because of this, some properties such as the amount of energy at the focal point or at the photoreceptors, the losses caused by reflection at the interfaces, cross-talks between each ommatidium and absorption cannot be examined. Finite-Difference Time-Domain (FDTD) method is a popular computational method and preferred in electromagnetic problem solving. It is also a simple and widely used method for discretization of the differential form of Maxwell's equations. In this study, we incorporate FDTD method for the wave analysis of compound eye in order to see the feasibility of designing novel infrared detectors. Electronic and photonic integration for future applications requires that the electricity be efficiently converted into an optical signal. Grafen material is one of the most suitable electronic and photonic properties for this work and suitable materials for connected systems with considerable wide working bandwidth. Infrared detectors perceives the infrared radiation from objects and these detectors have been used in defense industry for a long time in applications like target acquisition, surveillance, fire control, and missile seeker. This thesis aims to design unique infrared detectors based on bio-inspired optics. By mimicking the problem solving talents available in nature and with the FDTD method, the simulation of electromagnetic wave propagation in two and three dimensional structures will be performed. Moreover, the effect of compound eye structure on optic properties in mid-infrared region and far infrared region will be examined by wave propagation analysis.