A low loss transmission line is one of key elements for realization of sub THz band collective Thomson scattering (CTS) diagnostics in large fusion devices. This paper reports transmission tests of corrugated waveguid...
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ISBN:
(纸本)9781467384858
A low loss transmission line is one of key elements for realization of sub THz band collective Thomson scattering (CTS) diagnostics in large fusion devices. This paper reports transmission tests of corrugated waveguides with 300 GHz band gyrotron power. Two types of corrugated waveguide are considered. One is 1.25 inch corrugated waveguide. The other is 3.5 inch corrugated waveguide already installed in the Large Helical Device (LHD) for electron heating with lower frequency gyrotrons. At first, transmission test with existing 1.25 inch waveguides was carried out. This waveguide is not optimized for 300 GHz band and substantial attenuation along waveguides was observed. A theoretical analysis explaining the large attenuation is performed.
The real negative zeros (k) over cap ((c) over cap)((x) over cap(n) over cap) and (delta) over cap ((c) over cap)((x) over cap(n) over cap) ((n) over cap - 1, 2, 3, . . ., (p) over cap, (p) over cap - a finite positiv...
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ISBN:
(纸本)9781509060931
The real negative zeros (k) over cap ((c) over cap)((x) over cap(n) over cap) and (delta) over cap ((c) over cap)((x) over cap(n) over cap) ((n) over cap - 1, 2, 3, . . ., (p) over cap, (p) over cap - a finite positive integer) in thefirst parameter (k) over cap, resp. a of the real Kummer confluent hypergeometric function (Phi) over cap((a) over cap, (c) over cap;(x) over cap) with (a) over cap, (c) over cap and (x) over cap - all real, (a) over cap < 0, <(c)over cap> > 0 and (x) over cap > 0, (a) over cap,= (c) over cap /2 + (k) over cap ((k) over cap = 0,- (c) over cap /2 - real, negative, infinity < <(k)over cap> < <(c)over cap>/2), resp., (a) over cap - arbitrary real negative, are investigated numerically for selected values of (n) over cap, assuming x and c as parameters. The results are presented in the form of Tables and graphs. Analyzing them, certain properties of the zeros are revealed and summarized in three theorems which are substantiated numerically and analytically. Theorem 1 states that when (x) over cap -> + infinity, then (k) over cap (((c) over cap))((x) over cap, (n) over cap) and (delta) over cap (((c) over cap))((x) over cap, (n) over cap) tend to the real positive numbers (K) over cap (1)(((x) over cap, (n) over cap)) = -((n) over cap - 1) - ((c) over cap /2), relevantly (A) over cap (1)( n) = -((n) over cap - 1), and in case (x) over cap -> 0, both quantities of interest go to - infinity. Theorem 2 determines the number n of zeros studied. It ascertains that it is finite and depends on their values. According to it (n) over cap = 1, 2,..., (p) over cap, where (p) over cap = abs[(delta) over cap (((c) over cap))((x) over cap, (n) over cap)], correspondingly (p) over cap = abs[ (k) over cap (((c) over cap))((x) over cap, (n) over cap) + (c) over cap /2], ([(delta) over cap (((c) over cap))((x) over cap, (n) over cap)] is the greatest integer less than or equal to (delta) over cap (()c() over cap, 1) (((c) over cap))). Theorem 3 specifies the
waveguides with arbitrary cross-section and periodic loading are analyzed using an eigenmode projection technique. The analysis procedure is based on expanding the fields of the given structure in terms of the solenoi...
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ISBN:
(纸本)9781509006984
waveguides with arbitrary cross-section and periodic loading are analyzed using an eigenmode projection technique. The analysis procedure is based on expanding the fields of the given structure in terms of the solenoidal and irrotational eigenmodes of a canonical waveguide with cross-section enclosing that of the original waveguide. Floquet harmonics are incorporated in the canonical eigenmodes to account for the periodicity. Results obtained using the proposed approach and other techniques are compared and show excellent agreement. The proposed approach has many advantages, namely that the problem reduces to a simple eigenvalue problem and the field distribution is directly given as weighted expansion of the canonical eigenmodes.
We demonstrate the generation of ultra-broadband supercontinua in Si3N4 waveguides at a pump wavelength of 1560nm. The supercontinuum extends to beyond 2.6 mu m wavelength in the infrared and has a spectral width of m...
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ISBN:
(纸本)9781943580118
We demonstrate the generation of ultra-broadband supercontinua in Si3N4 waveguides at a pump wavelength of 1560nm. The supercontinuum extends to beyond 2.6 mu m wavelength in the infrared and has a spectral width of more then 453THz.
We investigate the novel characteristics of coupled waveguides exhibiting state eigenmode degeneracies and gain. We explore the theory of such coupled-waveguides with exceptional points of degeneracies (EPD) using a g...
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ISBN:
(纸本)9781509018031
We investigate the novel characteristics of coupled waveguides exhibiting state eigenmode degeneracies and gain. We explore the theory of such coupled-waveguides with exceptional points of degeneracies (EPD) using a generic coupled transmission-line (CTL) approach. We show that giant enhancement in the local density of states (LDOS) occurs in finite length resonators with second and fourth order degeneracies. We also demonstrate the possibility of low threshold generation (lasing) in such cavities. The developed framework provides a promising performance boost for several applications including low threshold lasers, highly efficient high microwave power sources, and sensors.
We study the optical performances of microring resonator modulators fabricated on 200 mm SOI wafers to select the ring resonator modulators for targeted ONoC and optical interposer applications. Counter-doped ring res...
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ISBN:
(纸本)9781628419887
We study the optical performances of microring resonator modulators fabricated on 200 mm SOI wafers to select the ring resonator modulators for targeted ONoC and optical interposer applications. Counter-doped ring resonator modulators were fabricated to guarantee the absence of unexpected p-i-n junctions in the ring waveguide due to overlay misalignments inherent to successive fabrication steps. The fabricated add-drop ring resonator modulators showed good DC performances with a V pi L at 1.55 ***. Finally, ultra-low loss waveguides were realized to allow long distance data transport on photonic chips.
In this paper, we propose that both the quasi-transverse-magnetic (TM) and quasi-transverse-electric (TE) Airy plasmons can be supported in graphene-based waveguides. The solution of Airy plasmons is calculated analyt...
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ISBN:
(纸本)9781509020171
In this paper, we propose that both the quasi-transverse-magnetic (TM) and quasi-transverse-electric (TE) Airy plasmons can be supported in graphene-based waveguides. The solution of Airy plasmons is calculated analytically and the existence of Airy plasmons is studied under the paraxial approximation. Due to the tunability of the chemical potential of graphene, the self-accelerating behavior of quasi-TM Airy plasmons can be steered effectively, especially in multilayer graphene based waveguides. Besides the metals, graphene provides an additional platform to investigate the propagation of Airy plasmons and to design various plasmonic devices.
Graphene is different from most optical materials in that it is a thin material layer with a thickness as small as one atom. Graphene layers can be incorporated into optical simulations using either a surface conducti...
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ISBN:
(纸本)9781628419856
Graphene is different from most optical materials in that it is a thin material layer with a thickness as small as one atom. Graphene layers can be incorporated into optical simulations using either a surface conductivity material model or a volumetric permittivity material model;however, introducing graphene through a volumetric permittivity is computationally inefficient because it requires very fine discretization grids. We have recently developed a more efficient approach that enables the use of comparatively coarse grids by formulating a discretization of Maxwell's equations (in the time or frequency domains) that combines a surface conductivity description of graphene layers with a volumetric permittivity description of other optical materials. This approach includes the full dispersion characteristics of graphene as specified by the Kubo formula. This paper demonstrates how the combined material description approach can be used to efficiently model state-of-the-art devices that take advantage of the energy confinement provided by surface plasmons. We show how to efficiently model TE and TM polarized surface plasmons, a surface plasmon waveguide switch, and an electro-optical modulator. This last example also includes electrical simulations of graphene and demonstrates how both optical and electrical simulations can be combined to produce a complete model of a graphene based device. For each example, we compare with previously published results, including experimental results.
Usage of multilayered filling in cylindrical transmission lines allows changing the cutoff frequencies, suppress undesirable modes and even change the type of fundamental mode in circular waveguide. In-homogeneously f...
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ISBN:
(纸本)9781509013227
Usage of multilayered filling in cylindrical transmission lines allows changing the cutoff frequencies, suppress undesirable modes and even change the type of fundamental mode in circular waveguide. In-homogeneously filled waveguides are widely used for development of resonators, filters, rotary joints etc. In this article, a mathematical model of such guiding structures based on the Green's functions and the method of radial equivalent lines, is demonstrated. This model is used to calculate frequency dependencies of propagation constant in multilayered circular waveguide. Algorithm's fast response time is demonstrated. It is also shown that the growth of calculation time with number of layers in structure is much slower at proposed technique than at commonly used methods.
The effective Kerr and two photon absorption (TPA) nonlinear parameters of a nano-waveguide are characterized by means of a bi-directional top hat D-Scan technique. This approach requires a single beam and allows the ...
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