We present the fabrication and light transmission through a hollow core fiber bundle with seven cores arranged in a hexagonal pattern. Each individual core facilitates independent light propagation and exhibits several transmission windows in the near infrared region. The lowest measured loss is 2.5 dB/m near 600 nm, with the broadest transmission window located between 1250 nm and 1450 nm with a loss of 4 dB/m.
We investigate the use of a spatially distributed beam of entangled photons for applications of wavefront division interferometry. Using a fiber-based spontaneous parametric down conversion process, which redirect the signal and idler into a common single-mode fiber, we generate a Gaussian beam of colinear entangled photons randomly distributed in space. Coincidence measurements carried by wavefront division demonstrate quantum interference patterns, including classical single photon fringes, two-photon interferences and the Hong-Ou-Mandel effect. Our results are relevant for detecting transverse variations in the statistical properties of weak turbulence.
KEYWORDS: Zinc selenide, Thermography, Long wavelength infrared, Design and modelling, Silicon, Metalenses, Transmittance, Semiconducting wafers, Modulation transfer functions, Deep reactive ion etching
Wide field-of-view optics are crucial optical elements with extensive applications in imaging, display, and sensing. Conventional wide FOV optics rely on cascading multiple refractive optical elements to assemble ‘fisheye lenses’ that correct third-order Seidel aberrations. Here we experimentally demonstrate a flat lens design that achieves 140◦ FOV in the long-wave infrared band. The metalens was fabricated on a monolithic float zone Si wafer leveraging photolithography and deep reactive ion etching. Large metalenses with diameter exceeding 4 cm have been realized using this approach. Thermal imaging at ambient temperature was validated by coupling the metalens with a LWIR focal plane array.
The dramatic optical property change of optical phase change materials (O-PCMs) between their amorphous and crystalline states potentially allows the realization of reconfigurable photonic devices with enhanced optical functionalities and low power consumption, such as reconfigurable optical components, optical switches and routers, and photonic memories. Conventional O-PCMs exhibit considerable optical losses, limiting their optical performance as well as application space. In this talk, we present the development of a new group of O-PCMs and their implementations in novel meta-optic devices. Ge-Sb-Se-Te (GSST), obtained by partially substituting Te with Se in traditional GST alloys, feature unprecedented broadband optical transparency covering the telecommunication bands to the LWIR. A drastic refractive index change between the amorphous and crystalline states of GSST is realized and the transition is non-volatile and reversible.
Optical metasurfaces consist of optically-thin, subwavelength meta-atom arrays which allow arbitrary manipulation of the wavefront of light. Capitalizing on the dramatically-enhanced optical performance of GSST, transparent and ultra-thin reconfigurable meta-optics in mid-infrared are demonstrated. In one example, GSST-based all-dielectric nano-antennae are used as the fundamental building blocks for meta-optic components. Tunable and switchable metasurface devices are developed, taking advantage of the materials phase changing properties.
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