Fig 6 - uploaded by Ekmel Ozbay
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(a) EM wave transmission through the first micromachined crystal along the stacking direction. The arrows indicate the calculated band-edge frequencies. (b) Transmission characteristics when the crystal is rotated 35°.
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The use of layer-by-layer geometry to build photonic band-gap crystals at various frequencies ranging from microwave to the far-infrared is described. The layer-by-layer structure yields a full photonic band gap in all directions, and this is experimentally confirmed at microwave frequencies. The structures are then built at smaller scales by means...
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... the first millimeter-wave crystal 7.62-cm silicon wa- fers with a resistivity of 30 cm 1 were used. Figure 6(a) shows the transmission measurement for propaga- tion along the stacking direction (normal to the silicon wafer surfaces) of this crystal, which has 28 stacked sili- con wafers (7 unit cells). The drop-off in transmitted power, corresponding to the valence band edge for the crystal, starts near 81 GHz, which matches the calculated value exactly. ...
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... sili- con wafers (7 unit cells). The drop-off in transmitted power, corresponding to the valence band edge for the crystal, starts near 81 GHz, which matches the calculated value exactly. The upper band edge for this orientation, predicted to be at 120 GHz, was beyond the upper mea- suring limit of the W-band test set and so does not appear in Fig. 6(a). In the forbidden band the average attenua- tion was 60 dB, a limit that was most likely due to leak- age of the EM power around the sample, either through surface states of the crystal or through other leakage paths around the crystal. The upper band edge was de- tected when the crystal was rotated so that the EM wave was incident at ...
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... tected when the crystal was rotated so that the EM wave was incident at an angle of 35° with respect to the wafer surface normal [see Fig. 1(c) for a pictorial description of this propagation direction]. Then the complete band gap fell within the measurement range of the experiment, and both edges of the band gap were well defined, as shown in Fig. 6(b). The valence band edge occurred at 76 GHz, and the conduction band edge was at 116 GHz, values that are in good agreement with the calculated values of 79 and 117 ...
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... part of the crystal. This attenuation, along with the reflectance loss of 3.0 dB that arises from the air-dielectric interfaces, ex- plains the 40-dB loss measured through the W-band fre- quencies. Free-carrier absorption can also be used to ex- plain the relatively low transmission (10 dB) values measured for the conduction and valence bands in Fig. ...
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... minimize the free-carrier absorption problem, a sec- ond crystal was fabricated by use of silicon wafers with a typical resistivity of 180 cm, and its propagation char- acteristics at W-band frequencies were measured. 22 those used for Fig. 6(b)] when the crystal was rotated 35° with respect to the wafer surface normal. The peak transmission for both conduction and valence bands was only 5 dB below the incident signal, which was better than the transmission obtained from the first crystal. For the second crystal the free-carrier absorption was less than that of the first ...
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A three-dimensional diamond photonic crystal with an ultra-wide tunable bandgap and resonant mode has been proposed based on a liquid medium approach. A bandgap tuning range of up to 12.8% is achieved in the microwave regime. The liquid-infiltrated photonic crystal is realized by using a low-loss liquid medium of which a large refractive index vari...
Citations
... PhCs are able to create ranges of frequencies called photonic bandgaps (PBGs) where light is strongly reflected [4][5][6][7][8]. In the early stage after the concept of PhCs was proposed, researchers mainly focused on two-dimensional (2-D) [9][10][11][12] and three-dimensional (3-D) PhCs [13][14][15][16]. In 1998, researchers found that omnidirectional PBGs can exist in all-dielectric one-dimensional (1-D) PhCs [17]. ...
In recent years, researchers utilized Tamm plasmon polaritons (TPPs) in conventional heterostructures composed of a metal layer, a dielectric spacer layer and an all-dielectric one-dimensional (1-D) photonic crystal (PhC) to achieve high-efficiency absorption of graphene. According to the Bragg scattering theory, photonic bandgaps (PBGs) in all-dielectric 1-D PhC strongly shift toward shorter wavelengths (i.e., blueshift) as the incident angle increases. Therefore, TPPs in conventional heterostructures also show strongly blueshift property. Such strongly blueshift property of TPPs greatly limits the operating angle range of the high-efficiency absorption of graphene. Herein, we realize an angle-insensitive TPP in a heterostructure composed of a metal layer, a dielectric spacer layer and a 1-D PhC containing hyperbolic metamaterial layers. Empowered by the angle-insensitive property of the TPP, we achieve wide-angle high-efficiency absorption of graphene. The operating angle range (A > 80%) reaches 41.8 degrees, which is much larger than those in the reported works based on TPPs and defect modes. Our work provides a viable route to designing cloaking devices and photodetectors.
... Since the original work of Yablonovitch [4] and John [5], on photonic crystals have intensively used in the design of optical devices including low-temperature sensors [6], biosensors [7], thermophotovoltaic applications [8], multichannel filters [9], antireflections [10], fractal band-edge lasers [11], Wideband Antennas [12], etc. during last years, they are studied as some one-, two-and three-dimensional objects [13,14]. Also, many techniques have been employed to fabricate the dielectric layer-by-layer photonic crystals at different frequency regimes [15][16][17][18][19]. Besides, to numerically consider the photonic crystals different approaches have been used including, coupledmode theory [20], envelope-function approximation [21], finite-difference time-domain [22], Finite-Element Time-Domain [23], multidomain pseudospectral method [24], transfer matrix method [13], etc. ...
In this study, for the first time, we present a new way of producing novel quasi-periodic multilayers based on the multiplication of some primitive available sequences such as Thue–Morse, Fibonacci (of two types N and P), Cantor, and constant length square sets. We also present some pseudo-codes to create these multilayers. Using a one-dimensional transfer matrix method, we obtain the transmission coefficient for some plasma-dielectric photonic crystals. Although, employing the above-mentioned approach many new sequences may be obtained, but for conciseness purpose, we analyze the photonic band gaps of a limited number of multilayers obtained in this way. We consider the effect of the number of layers, the refractive index of the dielectric later, multiplication of different fractal sets, etc., on the electromagnetic wave transport properties.
... In such structures, the permittivity is a periodic function in space. In case when the dielectric permittivity function repeats itself in one dimension (1D) the structure is called one-dimensional photonic crystal (1D PC) [4], if it repeats itself in 2D or 3D the structure is called 2D or 3D PC [5,6]. ...
... As for value of dielectric loss tangent, it is equal to 0.003 for epoxy layers and increases from 0.003 to 0.3 in composite layer with increase of filler content. Also, quasiperiodic PS4 (LH) 5 During the investigation of EMR shielding (frequency ranges of 26-37.5 GHz and 37.5-54 GHz) of photonic structures, the basic parameters, that were measured are the standing wave ratio by voltage (SWR), related to EMR reflection index r = (SWR − 1)/(SWR + 1) and transmission index t, which defines full attenuation of EMR during shield transition due to EMR reflection processes on layer boundaries and EMR absorption inside the shield. The samples of composite materials with cross section of 7.2 × 3.4 mm 2 (or 2.6 × 5.2 mm 2 ) were placed in cavity of rectangular waveguide and completely fill its cross section. ...
... Firstly, we have modeled the transmission spectra for PC with epoxy and epoxy-filled layers with known material parameters ε ′ r1 and ε ′ r2 . PS structure consisted of ten layers (five periods, (LH) 5 ) and placed in rectangular waveguide. For simulating the EMR transmission spectra for PC, the transmission line (TL) method is being used, when the reflection coefficient at the surface of the first layer is obtained by starting the calculations from the last layer using the impedance matching concept. ...
This work presents the results of computer modeling and experimental measurements of microwave transmission properties for one-dimensional periodic multi-layered photonic structures (PCs), composed of epoxy layers and composite layers filled with nanocarbon particles—multi-walled carbon nanotubes and graphite nanoplatelets. The results show that the characteristics of observed photonic band gaps in transmission spectra of PC can be controlled by varying the parameters of layers, namely, the complex permittivity and the layer thickness. It was found that the insertion of the defects (for instance, magnetic layer) into photonic structure can change the EMR transmission spectrum. The comparative analysis of EMR transmission spectra for investigated photonic structures has showed good agreement between the experimental and simulated data. It was found that EMR absorption in composite layers of photonic structures shifts the transmission spectra to the smaller values of EMR transmission index and reduces the sharpness of photonic band gaps. Thus, by changing the parameters of composite layers in photonic structure, we can obtain the tunable photonic band gaps, necessary for technological applications in devices, capable of storing, guiding, and filtering microwaves.
... Dado que estas primeras publicaciones se centraban en el rango óptico, se denominaron a esas nuevas estructuras cristales fotónicos o PBG (Photonic Band Gap). A finales del siglo XX, aparecen los primeros trabajos de estructuras de banda prohibida con periodos milimétricos y submilimétricos [7], [33] - [38]. Esto obliga a adaptar la denominación de esas estructuras para que no induzca a confusión sobre los rangos de frecuencia donde es posible su funcionamiento [39]. ...
This thesis focuses on the analysis and synthesis of microwave devices. More specifically,
three types of cell structures metamaterials have been developed. They have been
applied to the original design of compact filters in planar technology (microstrip, coplanar
waveguide CPW and substrate integrated waveguide SIW). The proposed cells and
devices may be of great interest for future communication systems. On the one hand,
the planar technology is a mature and low cost method of manufacturing, and on the
other hand, the devices based on metamaterial structures show unique electromagnetic
properties which will make possible reducing the size and overcoming the limitations of
conventional devices. Among the different metamaterials existing, we used those belonging
to electromagnetic crystals (Electromagnetic Band Gap, EBG) and Veselago
media. Conventional EBGs in microstrip technology are a periodic structure with one
row of circular patterns etched on the ground plane. This structure exhibits bands of
frequencies in which electromagnetic propagation is not allowed as a Bragg reflector.
EBG structures proposed changing the circular patterns by cells based on fractal geometry
Koch (KFEBG), created from a hexagonal shape. KFEBG cells allow the realization
of structure with r/a (radii/period) ratio higher than 0.45 (which is the upper limit of the
conventional 1-D EBG structure). When r/a <0.5, the microstrip-KFEBG structure has
the same behavior as a conventional microstrip-EBG structure (Bragg reflector), however
when r/a > 0.5, the microstrip- KFEBG structure presents a wide stopband, unusual
on this kind of configuration. Therefore, the periodic structure KFEBG is applied to
r/a> 0.5 in the design of compact low-pass filters in microstrip technology and SIW. In
order to improve the frequency response and reduce the size of these filters, a modulated
apodization of the design parameters was performed. And finally, an original synthesis
method to achieve these designs is developed. Furthermore, Veselago media, also
called left-handed materials (LH), are characterized by real parts of permittivity and
permeability negative simultaneously. These media make possible the spread of regressive
waves among other unusual phenomena. First cells are based on split ring resonators
(SRR) and complementary split ring resonators (CSRR) coupled to a transmission
line. Later, the open versions OSRR (Open Split ring resonator) and OCSRR (Open
Complementary Split ring resonators) are developed; these cells allow direct connection
to the transmission line, a greater ability to design devices and a reduced size compared
to SRR and CSRR cells. In this work, two new cells based on open rings resonators are
presented, OISRR (Open Interconnected Split Ring Resonator) is a mono-planar cell as
above and DOSRR (Double- Sided Open Split Ring Resonator) is a bi-planar cell with
design parameters in two different planes. Both cells have a reduced size like OSRR and
show interesting features. The DOSRR and OISRR cells were applied to the design in
planar technology of compact band-pass filters with high levels of rejection and high
selectivity compact stop-band filters (notch), respectively.
... This unique property helps to block the propagation of some wavelength, and allows other spectra; thus can effectively be considered as optical bandpass filter [3]. This phenomenon can be explained by the principle of Bragg's reflection [4], where we assume that wavelength of light will be of the order of layer dimensions [5]. Materials exhibit photonic bandgap can be used in designing photonic crystal fiber [6], which may replace the conventional optical fiber due to its highly improved performance from communication point-of-view [7]. ...
In this paper, eigenmodes of one-dimensional multilayer photonic crystal structure is analytically computed using transfer matrix technique. Refractive index contrast ratio is calculated along with reflectivity and transmittivity as a function of indices assuming direction of wave propagation is along the confinement. Photonic bandwidth is computed under weak and strong coupling conditions between forward and backward propagating waves for different material systems. Result shows that width of photonic bandgap increases with increasing the contrast ratio. Simulation is useful for experimental researchers to determine the bandwidth centered at 1550 nm for sole purpose of optical communication. Keyword(s): Eigenmode, Photonic crystal, Transfer matrix technique, Refractive index contrast ratio, Photonic bandwidth, Material composition 1. Introduction Propagation of electromagnetic wave through the structures with periodicities along the direction of confinement suffers dispersive effects. This is already exhibited in photonic crystal where permittivity of the dielectric material undergo periodic changes, result in photonic bandgap [1-2]. This unique property helps to block the propagation of some wavelength, and allows other spectra; thus can effectively be considered as optical bandpass filter [3]. This phenomenon can be explained by the principle of Bragg's reflection [4], where we assume that wavelength of light will be of the order of layer dimensions [5]. Materials exhibit photonic bandgap can be used in designing photonic crystal fiber [6], which may replace the conventional optical fiber due to its highly improved performance from communication point-of-view [7]. It is used to construct optical transmitter [8], switch [9], waveguide [10] etc. Bandgap of 2D photonic crystal is studied by varying column roundness by Hillebrand [11] using plane-wave expansion method. Recently, finite-difference-time-domain method is used to analyze the forbidden region of photonic crystal with different geometries [12]. Zhao calculated the width of bandgap [13] using Bragg's principle of reflection. Men optimized the computational problem using semi-definite programming and subspace methods [14]. Evolutionary algorithm [15] and level-set method [16] are also used for design of large bandgap crystal.
... Для проверки работоспособности предложенной модификации метода погружения было проведено сопоставление результатов физического эксперимента [Ozbay, 1996] с результатами численного моделирования на основе уравнений (4),(5). Был рассмотрен ФК (рис. ...
Modification of the invariant imbedding method to describe the interaction of 3D electromagnetic field with "woodpile" photonic crystal of finite thickness is considered in this paper. This modification allows solving a problem of evanescent modes resonant amplification during numerical calculations for the first layer of photonic crystal. The mathematical model created in this work gives good agreement with physical experiment results.
... Larger structures, designed for longer wavelengths, can act as useful models of the behaviour to be expected when the equivalent design is fabricated for shorter wavelengths. Both two-dimensional [5, 6] and three-dimensional78910111213 photonic crystals have been described. Recently, the value of optical components specifically for THz applications has become a more compelling factor, leading to an increasing interest in the THz properties of periodic systems14151617181920212223. ...
In this paper, we report our experimental study on two-dimensional photonic crystal slabs embedded inside parallel-plate metal waveguides, using terahertz time-domain spectroscopy. We observe that the temporal response of the photonic crystal slabs is significantly dispersed, indicative of strong dispersion near the edges of the photonic band gap. In the frequency domain, we observe several gaps whose sizes compare well with those from transfer matrix calculations. The group velocity and group velocity dispersion are characterized using a short-time Fourier transform analysis, and the results are consistent with the predictions from the photonic band structure. We have also measured reflection spectra using the photonic crystal as a 90 • turning mirror, and in this way demonstrated frequency-selective components for quasi-optic guided wave propagation of terahertz pulses.
... -10-Professor Ekmel Ozbay and his colleagues at Bilkent University in Turkey have carried out an extensive program of research on microwave applications of band-gap structures 28 . Much of their research has made use of the "log-pile" structure 29 shown in Fig 9a. (This structure is also called a "layer-by-layer" photonic band gap crystal.) ...
... In our experiments, we used a layer-by-layer structure [20,21] which was constructed by using square-shaped alumina rods (0.32 cm × 0.32 cm × 15.25 cm) of refractive index 3.1 at microwave frequencies. The stacking sequence repeats every four layers, which has the equivalent geometry of a face centered tetragonal (fct) lattice, corresponding to a single unit cell in the stacking direction. ...
... As shown in Fig. 8(c), the tuning bandwidth of the RCE detector extends from 10.5 to 12.8 GHz. This tuning bandwidth of the RCE detector is in good agreement with the full photonic band gap (10.6-12.7 GHz) of the crystal [21]. As expected, the measured enhancement factors are relatively higher when compared with the symmetrical defect case. ...
Abstract—We have demonstrated guiding and bending of electromag- netic (EM) waves in planar and coupled-cavity waveguides built around three-dimensional layer-by-layer photonic crystals. We observed full transmission of the EM waves through these waveguide structures. The dispersion relations obtained from the experiments were in good agree- ment with the predictions of our waveguide models. We also reported a resonant cavity enhanced (RCE) effect by placing microwave detec- tors in defect structures. A power enhancement factor of 3450 was measured for planar cavity structures. Similar defects were used to achieve highly directional patterns from monopole antennas.
In this work, we have studied transmission properties of a photonic crystal-like structure that can be woven into fabrics. An interesting possibility emerges when considering the potential energy savings through suppression of radiation. It is a well-established fact that every object at a finite temperature inherently emits electromagnetic waves. Within the specific context of the human body, radiation takes on a crucial role as a fundamental mechanism governing heat dissipation. Thus, exploring ways to manage or mitigate this radiation could offer innovative approaches to optimize energy consumption and enhance heat regulation. It is well known that a photonic crystal can block electromagnetic energy with a specific frequency that is falling into a photonic bandgap. By using the numerical method called a finite-difference time domain, we have shown that this property of a periodic structure can be used to make textiles to save energy that is used to heat a human body environment. Numerical calculations have shown that by using the proposed photonic crystal structure, 53% of electromagnetic energy is reflected. Although we mainly focused on textiles, it is worth highlighting that the same fundamental principle can be extended to diverse fields; for example, this structure can be integrated with construction materials and effectively function as a radiation heat insulator.
