Abstract—A variable coupling ratio Y-Branch plastic optical fiber (POF) coupler based on acrylic has been developed. This device utilized two optical designs: a Y-branch structure with a novel suspended waveguide taper and a simple attenuation technique based on lateral displacement of two fibers for the non-symmetrical coupling ratios. The high index contrast waveguide taper is constructed on the acrylic block itself where the area surrounding the waveguide taper has been designed in such a way that it is surrounded by an open air. A simple attenuation technique based on lateral displacement of two adjoining fibers for each of the two output ports has been proposed and presented for the non-symmetrical coupling ratios. Lateral displacement of the fiber is set from 4.4 mm down to 1.6 mm for output fiber 1 and 0.1 mm to 1.0 mm for output port 2. Numerical analysis has been done on the lateral displacement of the output fibers which shows the device is able to generate non-symmetrical coupling ratios. Device modeling has been performed using non-sequential ray tracing technique on the Y-branch coupler performing as a 3 dB coupler with an excess loss of 1.84 dB and a coupling ratio of 50 : 50. The designed coupling ratios vary from 1% to 45% for port 1 and 99% down to 55% for port 2 whereas in the simulated device, ratios vary from 7.65% to 39.85% for port 1 and from 92.35% down to 60.15% for port 2. Fabrication of the device is done by producing the device structures on an acrylic block using high speed CNC machining tool. The fabricated device has an excess loss of 5.85 dB while the coupling ratios are 56.86% and 43.14% when operating as a 3 dB coupler. In the
curves and the dispersion characteristics in the neighborhood of the branch points for gyro-electric medium loaded lossless cylindrical metallic waveguide are investigated by expressing the propagation constant in the form of infinite series by aid of algebraic function theory. The presented method uses the linear algebraic equations system of transmission line voltages and currents belonging to the structure and the algebraic characteristic equation of the truncated version of this system to obtain coefficients of the series. This approximation provides a model of the dispersion curves in the neighborhood of the branch points with Puiseux series which has only two non-zero coefficients and no negative power terms. In numerical examples, dispersion characteristics of plasma column loaded cylindrical metallic waveguide are obtained from the exact solution, the Method of Moment and the Puiseux series and the results are presented comparatively on the same figures.
completed polymeric waveguide device is inserted into the acrylic insert shown in Figure 8(b). Finally, input and output POFs are slotted into the U-grooves and butt coupled to the ends of the waveguides. Figure 8(c) shows the assembled 1 × 2 Y-branch POF coupler with the acrylic insert and external POFs. In order to reduce the coupling loss as much as possible, the cutting tool from Ratioplast-Optoelectronics (Germany), which produce a clean cut of the POF and hence requires no end polishing has been utilized. The additional insertion loss due to the POF is about 0.5 dB. Hence, the total loss introduced by the ﬁber-waveguide coupling is about 1 dB. The test wavelength is set at 650 nm. The eﬀective input power Pin is set at 0 dB or 1 mW. The output power detected at both output ports are P 1 = 0 . 1513 mW and P 2 = 0 . 1059 mW respectively. The coupling ratio of the fabricated device is 58:42. The insertion losses of this device are 8.2 dB and 9.75 dB respectively whereas the excess loss is 5.89 dB.
The fourth situation is when both the inputs are equal to one. In this case the two pulses meet at the converging point between the main waveguide and the secondary waveguide. In this case, since we are in soliton propaga- tion condition, they can attract if their relative phase is included between zero and /2 or between 3/2 and 2, or they can repel if their relative phase is included be- tween /2 and 3/2. If the length of the secondary waveguide is chosen to generate a repulsive condition, the two solitons propagate in the main waveguide prop- erly separated until reaching the bifurcation point be- tween the main waveguide, the delay branch and the drain waveguide. At this point the two solitons detach: the first one enters the delay branch while the second one enters the drain waveguide.
at 5.6 dB. Finally, the device fabricated by Takezawa et al. is another Y-branch POF coupler based on planar waveguide technology. Here, they have adopted injection molding technique to fabricate the devices. The mold insert was fabricated using mechanical technique. The core and the cladding are basically polymer material suitable for injection molding. This device has an insertion of 4.41 dB. Nevertheless, all of these devices required expensive production equipment and in-factory precision assembly tools. In addition, these devices are unsuitable for a ‘do-it-yourself’ (DIY) optical device.
that in Dynamena and related species, polyps and stem tip keep a regulated distance from each other. These propositions also explain that in successive internodes the polyps form as closely as possible to each other. Usually polyps form in rows along the longitudinal axis (Fig. 5). This pattern is caused by a particular feature of the shoot tips: In the tip, cell proliferation is very rare (for review, see Kosevich, 2004). Thus the new primordia that form in lateral position include tissue that derives from tissue proximal to the tip (as observed in Laomedea, sympodial growth). This tissue has a differential origin in the circumference. Tissue at a certain position derives from or is influenced by the adjacent hydranth primordium; tissue at other positions is not. Thus in successive internodes polyps form in longitudinal rows. They form in tissue that at the outset has a higher positional value than does other tissue lying at the same distance to the existing stem tip. The very same proposition has been made for branch positioning in thecates with sympodial growth (see earlier discussion). With respect to Dynamena, to my knowledge such an export of tissue out of a hydranth into the surroundings has not been demonstrated to occur but has been shown for Hydractinia echinata (Müller, 1964). It appears that in contrast to Hydra and sympodially growing Thecata, monopodially growing Thecata have developed an additional way of controlling where primordia form and how many form. In all Thecata, the positional value controls the area of the tip that is not covered by hardened perisarc. Only in Thecata with monopodial growth do new primordia form within this area (sec- ondary branches and gonozoids, both of which form late, are ignored). The size of this area determines how many additional primordia can form. Thus a self-organizing process controls, via
out correction. The phylogenetic relationships among the six studies suggest that D. erecta and D. orena are more dis- species are depicted in Figure 1, which is supported by most tantly related to D. melanogaster than D. yakuba, as illus- previous studies (e.g., Jeffs et al. 1994). The nucleotides at trated in Figure 1 (Solignac et al. 1986; Cariou 1987; the nodes were estimated as those that require the smallest number of total substitutions, and sites at which any node Jeffs et al. 1994; Shibata and Yamazaki 1995). The y
travels through the acoustic waveguide the refractive index of the medium is changed according to the pressure variations in the compressions and rarefactions of the wave. Actual data shows that the relation between refractive index and pressure is linear for most cases (fig. 5, 6). Thus, the peak to peak pressure variation in the acoustic waveguide introduces a change in optical path length of the object beam as it passes through the waveguide, and hence effects the phase shift, §.
The design of a power dividing input coupler for a 372 GHz HOM gyro-TWA is presented. The numerical modelling of a waveguide splitter input coupler with a linear taper power divider is presented in Section II. The linear taper and E-plane waveguide bend were simulated individually before the full design of the waveguide channel was completed. A tolerance study of the optimised waveguide coupler is discussed in Section III. A prototype waveguide coupler, scaled to operate at 90 – 96 GHz, was manufactured. A discussion of the coupler manufacture is included in Section IV and the Vector Network Analyser prototype testing is presented in Section V. Section VI discusses the design of the coupler at 93 GHz and 372 GHz.
2) Larmuseau MHD, Delorme P, Germain P, Wanderheyden N, Gilissen A, Geystelen A, Cassiman JJ, Decorte R (2013). Genetic genealogy reveals true Y-haplogroup of House of Bourbon contradicting recent identification of the presumed remains of two French kings. European Journal of human genetics, 22, 681-687.
Loizzo, M.R., Tundis, R., Menichini, F., Saab, A.M., Statti, G.A., Menichini, F., 2007. Cytotoxic activity of essential oils from Labiatae and Lauraceae families against in vitro humantumor models. Anticancer. Res., 27, 3293-3299. Lu, Y., Foo, Y.L., 2001. Antioxidant activities of polyphenols from Sage (Salvia officinalis). Food. Chem., 75, 197-202. Miller, A.B., 1976. Shaker herbs: a history and a compendium. General Publishing Company Limited: New York, 90. Mirjalili, M.H., Salehi, P., Sonboli, A., Vala, M.M., 2006. Essential oil variation of Salvia officinalis aerial parts during
By using the waveguide splitting technique, the waveguide structure is split in the H-plane, which creates two parts of the WR-10 rectangular waveguide. The bottom part is the rectangular waveguide structure without top metallic wall, resulting in an open rectangular-cross-section slot along the waveguide structure. The top part is the removable metallic lid used as a top wall of the slotted waveguide structure, forming a complete WR-10 rectangular waveguide. By reusing the bottom part of the waveguide structure and only changing the top waveguide lid, the life cycle of the tailor-made WR-10 waveguide is increased. Furthermore, it is simple and cost-effective to machine any desired slotted pattern into the top lid to accommodate various different sensor structures with different measurement purposes. The key requirement for the H-plane split waveguide in this work is to ensure that the top and bottom parts are assembled properly without any gap along the boundary to sustain a continuous current distribution on the waveguide walls without any unintended current and EM-field disruption. The bottom structure of the WR-10 waveguide is made of a copper block with the waveguide cross-section aperture of 2.54 mm 1.27 mm, allowing the TE 10 mode to propagate between 75 GHz and 110 GHz in
ABSTRACT: The demand for high performance, high gain, low cost, easy to fabricate and compact antennas for telecommunication and different applications has rapidly increased at microwave and higher frequencies. Substrate Integrated Waveguides (SIW) is planar in nature so it can be fabricated on planar circuits like Printed Circuit Boards (PCB) and can be integrated with other planar transmission lines like microstrips.Substrate Integrated Waveguides (SIW) keep the low loss property of their conventional metallic waveguides and are extensively used as interconnection in high speed circuits, filters, directional couplers, antennas. In this paper a Substrate Integrated Waveguide based antenna using rectangular slots is proposed and its integration with Microstrip line. ComsolMultiphysics is used for simulation results.
The use of the Lorentz lemma on reciprocity to the waveguide propagation of Maxwell optical radiation leads to the factorization of (2) into the sum of two terms involving the transverse electro- magnetic ﬁeld distributions and the exponential factor respectively. In the case of real ε and μ , the second contribution to the Lorentz lemma vanishes identically, while if Im ε Re ε , it is negligibly small. The remaining ﬁrst part of the sum, renamed as “conservation law”, can be called “truncated Lorentz lemma” for the waveguide propagation of the electromagnetic radiation.
Over which board level optical interconnects outperform conductive electrical wire lines is calcu- lated. Common electrical interconnects such as planar microstrip or two-wire lines su®er from high loss and crosstalk. This limits the maximum applicable length and maximum bandwidth-per-pitch of a link in a single or aggregated lines scenarios. In addition, to achieve high throughput in these electrical links, higher order modulation schemes and complicated equalizers are inevitable. This reduces the power e±ciency substantially and increases the cost and complexity of the system. Op-tical interconnects o®er very wide bandwidth, small crosstalk and extremely low transmission loss. Hence they can be used for short/long-range communication. However the cost and complexity due to high precision needed for assembly and electro-optical modules limits the application of such interconnects. Current approach based on a low-loss dielectric waveguide and its multi- mode excitation presents a large bandwidth over a reasonable length (around 1 m). In addition, the all- electrical and planar construction o®ers a low-cost
In conclusion, dynamically tunable PIT effects in gra- phene-based plasmonic nanostructure composed of a plasmonic bus waveguide side-coupled to U-shaped and rectangular nanocavities have been proposed and modeled by using finite element method. The dynamic tunability of the PIT windows is obtained by modifying the chemical potential of the nanocavities and plas- monic bus waveguide. Furthermore, the PIT window can be tuned dynamically via adjusting the geometrical parameters of the nanostructure, such as the location and width of the rectangular nanocavity. Compared to the conventional ring resonators [24, 25], our proposed asymmetric U-shaped and rectangular resonators offer stronger coupling strength between the resonators and the bus waveguide, which further results in the stronger PIT effect. On the other hand, unlike other reported nanoribbon waveguides, our structures are formed by the local variation of chemical potential on the identical graphene monolayer, and this provides the easier
For most single layer substrate integrated waveguide circuits, the top and bottom copper sheets are intact without slots and they are excited by a TE-like mode electromagnetic waves. These micro strip resonators can be treated as waveguide cavities with magnetic walls on the sides. The fields within the cavities can be expanded by the TEmn modes. Assuming no field variation normal to the substrate, thus the resonators may also be referred to as 2-D resonators since a resonance can occur in either of two orthogonal co-ordinates with only vertical electric and horizontal magnetic fields if the circuit is placed in the horizontal plane.
In the recent trend toward miniaturization, planar technologies such as microstrip and strip-line filters are more preferred than waveguide filters. However, the planar technologies are difficult to meet the high performance specification of bandpass filter application. Among all the filters, the cavity filters are the one that can meet the market demand. Cavity filter is a part of spectrum analyzer, thus, cavity filter requires operation with high performance to result in high accuracy and fine reading and provide high sensitivity. However, the main disadvantage of cavity filter is that it has a large size.