Near-infrared Subwavelength Imaging and Focusing Analysis of a Square Lattice Photonic Crystal Made from Partitioned Cylinders

Abstract

We study the focusing properties of a two-dimensional square-lattice photonic crystal (PC) comprising silica and germanium partitioned cylinders in air background. The finite difference time domain (FDTD) method with periodic boundary condition is utilized to calculate the dispersion band diagram and the FDTD method incorporating the perfectly matched layer boundary condition is employed to simulate the image formation. In contrast to the common square PCs in which the negative refraction effect occurs in the first photonic band without negative phase propagation, in our suggested model system, the frequency with negative refraction exists in the second band and in near-infrared region. In this case, the wave propagates with a negative phase velocity and the evanescent waves can be supported. We also discuss the dependency of the image resolution and its location on surface termination, source location, and slab thickness. According to the simulation results, spatial resolution of the proposed PC lens is below the radiation wavelength.

Broadband optical negative refraction based on dielectric phase gradient metagratings

“…Many ways of achieving negative refraction have been proposed, such as chiral media [10][11][12], photonic crystals [13][14][15], and electromagnetic (EM) metasurfaces [16,17]. The operating frequencies for negative refraction covers the microwave range [18,19], the terahertz range [20,21], the near-infrared band [21,22], and even visible light [18]. However, the negative refraction in visible * Authors to whom any correspondence should be addressed.…”

Recovering the Colors of Objects from Multiple Near-IR Images

“…By using CMM1, CMM2, and CMM3, the L*, a*, b* values of all 24 patches were recovered by using Eq. (9). Figure 11 shows a sRGB color image obtained by transforming the recovered L*, a*, b* values to sRGB using MATLAB [18].…”

“…Over the past 20 years, much research has been devoted to producing true-color images from near-IR imaging. The main focus of these studies involves the fusion of visible and infrared images, a technique for which the results are promising when the corresponding day-time images are available [4][5][6][7][8][9]. Meanwhile, attempts to produce color images by using only infrared light have led to the development of various applications in which a set of three sensors that are individually sensitive to different wavelengths in the near-IR band are used.…”