Browsing by Subject "Gratings"

Now showing 1 - 6 of 6

Open Access
Complex source radiation in a cylindrical radome of metal-dielectric grating
(IEEE, 1999) Altintas, A.; Ouardani, S.; Yurchenko, V. B.
The radiation fields of a line source enclosed in a circular dielectric radorne with grating consisting of an array of thin lossy metal strips are analyzed. The variations of the directivity of the source beam with respect to the beam direction are studied. The possibility of damping these variations by an appropriate design of the radome is demonstrated.
Open Access
Interdigital cantilevers for atomic force microscopy
(A I P Publishing LLC, 1996-10) Manalis, S. R.; Minne, S. C.; Atalar, Abdullah; Quate, C. F.
We present a sensor for the atomic force microscope (AFM) where a silicon cantilever is micromachined into the shape of interdigitated fingers that form a diffraction grating. When detecting a force, alternating fingers are displaced while remaining fingers are held fixed. This creates a phase sensitive diffraction grating, allowing the cantilever displacement to be determined by measuring the intensity of diffracted modes. This cantilever can be used with a standard AFM without modification while achieving the sensitivity of the interferometer and maintaining the simplicity of the optical lever. Since optical interference occurs between alternating fingers that are fabricated on the cantilever, laser intensity rather than position can be measured by crudely positioning a photodiode. We estimate that the rms noise of this sensor in a 10 hz–1 kHz bandwidth is ∼0.02 Å and present images of graphite with atomic resolution.
Open Access
One-way reciprocal spoof surface plasmons and relevant reversible diodelike beaming
(American Physical Society, 2013-05-15) Mutlu, M.; Cakmakyapan, S.; Serebryannikov, A. E.; Özbay, Ekmel
One - way excitation of spoof surface plasmons (SPs) and strongly pronounced diodelike extraordinary transmission of linearly polarized waves in the beaming regime can be obtained by combining spoof SPs and cross-polarization conversion resonances. The reciprocal composite structure that is suggested to realize this mechanism consists of a symmetric metallic grating with a subwavelength slit and a metamaterial based ultrathin 90 degrees polarization rotator and, therefore, shows the broken spatial inversion symmetry. In contrast to the earlier studies of SP inspired transmission through subwavelength slits, asymmetric (one-way) beaming is demonstrated at normal incidence and for both s- and p-polarized incident waves. Furthermore, as an implication of Lorentz reciprocity, the studied diodelike mechanism is reversible, which manifests itself in that transmission is significant for one of the two opposite illumination directions at s polarization and for the other direction at p polarization. The obtained numerical and experimental results verify the general idea and enable us to select the optimal operation regimes.
Open Access
An optical microcantilever with integrated grating coupler
(IEEE, 2009-06) Olcum, Selim; Karademir, Ertuğrul; Taş. Vahdettin; Akça, İmran; Kocabaş, Aşkın; Atalar, Abdullah; Aydınlı, Aydınlı
In this paper, we have fabricated an optical cantilever with an integrated grating coupler. We have used an inexpensive and repeatable method for integrating the grating to the silicon cantilever with a microfabrication compatible process. The sensitivity of the method can be further increased by integrating the detection circuitry onto the cantilever substrate. We believe that this is a promising method for sensing applications which provide a simple yet sensitive measurement technique using microcantilevers.
Open Access
Thermally mediated transmission-mode deflection of terahertz waves by lamellar metagratings containing a phase-change material
(2024-02-15) Serebryannikov, Andriy E.; Lakhtakia, Akhlesh; Ozbay, Ekmel
The planewave-response characteristics of simple lamellar metagratings exhibiting thermally mediated transmission-mode deflection (blazing) were numerically investigated, the unit cell of each metagrating containing a phase-change material chosen to be indium antimonide (InSb). Thermal control arises from the use of InSb in its insulator phase and the vicinity of the vacuum state. Metagratings of type A comprise parallel rods of InSb on silicon-dioxide substrate, whereas the substrate is also made of InSb in metagratings of type B. Both types exhibit thermally controllable deflection and asymmetric transmission, which occur when the real part of the relative permittivity of InSb is high. Narrowband features in the sub-diffraction regime may appear in a wide frequency range which involves the vicinity of the vacuum state, the real part of the relative permittivity of InSb being low then.
Open Access
Ultrahigh contrast one-way optical transmission through a subwavelength slit
(Springer, 2013) Battal, E.; Yogurt, T. A.; Okyay, Ali Kemal
We computationally demonstrate one-way optical transmission characteristics of a subwavelength slit. We comparatively study the effect in single layer and double layer metallic corrugations. We also investigate the effect of a dielectric spacer layer between double corrugations to control the volumetric coupling of plasmon and optical modes. We computationally show unidirectional transmission behavior with an ultrahigh contrast ratio of 53.4 dB at λ = 1.56 μm. Volumetric coupling efficiency through the nanoslit strongly depends on the efficient excitation of both the surface plasmon resonance and metal–insulator–metal waveguide modes. We show that the behavior is tunable in a wide spectral range.