We propose a thermally tunable terahertz narrow band filter by combining two different periodic waveguides. When the terahertz tube wall is corrugated periodically, the transparent spectrum presents a very complex str...
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We propose a thermally tunable terahertz narrow band filter by combining two different periodic waveguides. When the terahertz tube wall is corrugated periodically, the transparent spectrum presents a very complex structure as various pass and stopbands emerging. The terahertz wave cannot propagate through the waveguide when its frequency falls into the stopbands. When we connected two tubes with different types of stopbands, it is very intriguing that we have found an unexpected ultra-narrow-band transparency in the frequency gap. Our findings provide a more feasible and effective terahertz waveguide filter beyond these existing ones. By using the finite-element method, we have obtained the filtering characteristics of the proposed structures. The filter bandwidth could be narrowed from 2.3 GHz to 0.29 MHz by increasing the number of waveguide segments and the highest Q-factor achieved is about 3.5x10(6). Moreover, the tunability on temperature is obtained in a waveguide device of Au based on the combination of opaque structures.
A fully suspended mid-infrared (FSMIR) slot waveguide is proposed and experimentally demonstrated on a silicon-on-insulator (SOI) platform for the first time. The slotted waveguide core is mechanically supported by la...
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A fully suspended mid-infrared (FSMIR) slot waveguide is proposed and experimentally demonstrated on a silicon-on-insulator (SOI) platform for the first time. The slotted waveguide core is mechanically supported by lateral sub-wavelength grating claddings. The fabricated waveguides possess low propagation loss, which is measured to be 7.9 dB/cm at the wavelength of 2.25 mu m. With the underlying buried oxide (BOX) removed, the FSMIR slot waveguide has a broad spectral range of transparency that is limited only by the absorption of silicon. Numerical simulation shows that its sensitivity, defined as the ratio between the change of the effective index and the ambient refractive index, can reach 1.123, which is 9.7% higher than the maximal sensitivity of conventional SOI slot waveguides on BOX. (C) 2017 Optical Society of America
In this paper the behavior of mixed two-soliton solutions of the (3 + 1)-dimensional Yu-Toda-Sasa-Fukuyama (YTSF) equation with variable coefficients in two-layer liquid (or in an elastic) medium are shown. Indeed, th...
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In this paper the behavior of mixed two-soliton solutions of the (3 + 1)-dimensional Yu-Toda-Sasa-Fukuyama (YTSF) equation with variable coefficients in two-layer liquid (or in an elastic) medium are shown. Indeed, this equation shows two types of dispersive, namely longitudinal and lateral dispersion. Also, it shows flux transport in x and z-directions that arises from the nonlinear term. The geometric structure of solutions for the behavior of the propagation of the mixed-soliton waves may be characterized as in what it follows. (i) In Case when the longitudinal-dispersion coefficient is periodic. It is found that in the upper layer two-soliton waves mixed with a shock wave are propagating in the x-direction. While in the lower layer two-antisoliton waves mixed with a shock wave are propagating. In the both two layers the waves are periodic in time. This may be argued to the strong-coupling that arises from the dominance of the longitudinal dispersive. While in they-direction two-soliton and two-antisoliton waves are propagating in the upper and lower layers respectively. The flux transport in z-direction results to propagate train of two-soliton and two-antisoliton waves in the upper and lower layers respectively. (ii) When the coefficients of the coupling of the flux transport and dispersions are taken to increase of propagation for solitons occurs but with gaps. (iii) When the dispersion coefficient is a solitary wave, it is found that propagation of two-soliton waves incoming in the upper layer while two-antisoliton waves outgoing in the lower layer. (C) 2017 Elsevier B.V. All rights reserved.
We investigate polarization-insensitive waveguide designs afforded by the interplay of material and waveguide birefringence in LiNbO3-on-insulator photonic wires. Fundamental mode birefringence-free operation in the 0...
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We investigate polarization-insensitive waveguide designs afforded by the interplay of material and waveguide birefringence in LiNbO3-on-insulator photonic wires. Fundamental mode birefringence-free operation in the 0.8-1.8 mu m spectral range is predicted for a suitable choice of waveguide widths in the 375-600 nm range. Optimized buried waveguide designs yield broadband (1350-1625 nm) index matching between TE00 and TM00 modes. Furthermore, simultaneous phase- and group-velocity matching at infrared wavelengths appears feasible for pulse durations as short as 100 fs. (C) 2017 Optical Society of America
Electrically tunable channel waveguides have been fabricated by domain inversion of a LiNbO3 thin film bonded to a silicon wafer. The electro-optic effect is used to induce the waveguides and to alter its guiding prop...
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Electrically tunable channel waveguides have been fabricated by domain inversion of a LiNbO3 thin film bonded to a silicon wafer. The electro-optic effect is used to induce the waveguides and to alter its guiding properties. A low amplitude electric signal can tune the voltage-induced structure from an efficient waveguide to an antiguide giving a waveguide transmission that varies over more than 25 dB. The frequency response of the components is given. (C) 2017 Optical Society of America
作者：
Xu, HongnanShi, YaochengZhejiang Univ
Ctr Opt & Electromagnet Res State Key Lab Modern Opt Instrumentat Zhejiang Prov Key Lab Sensing Technol Zijingang Campus Hangzhou 310058 Zhejiang Peoples R China
An ultra-compact and highly efficient polarization rotator is proposed and experimentally realized on the siliconon- insulator (SOI) platform. The polarization rotation (TM0-TE1) process is obtained by utilizing a str...
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An ultra-compact and highly efficient polarization rotator is proposed and experimentally realized on the siliconon- insulator (SOI) platform. The polarization rotation (TM0-TE1) process is obtained by utilizing a straight multi-mode waveguide, while the mode conversion (TE1-TE0) process is realized by a bent multi-mode waveguide. For the proposed structure, only one etching step is required for the fabrication. The measured extinction ratio and insertion loss at the central wavelength are 19.8 and 0.86 dB, which agree well with the simulations. (C) 2017 Optical Society of America
The ability of the photoelastic effect in optical waveguides fabricated by Ti diffusion in a diaphragm of LiNbO3 for using as a pressure sensor has been investigated. We have studied the polarization rotation and phas...
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The ability of the photoelastic effect in optical waveguides fabricated by Ti diffusion in a diaphragm of LiNbO3 for using as a pressure sensor has been investigated. We have studied the polarization rotation and phase difference between TE and TM polarizations for the light transmitted from the waveguide that are induced by the external pressure. We have also studied the effect of position of the waveguides in the diaphragm on the pressure sensor's sensitivity. The polishing technique has been used to reduce the thickness of the diaphragm to 0.2 mm in order to increase the sensor's sensitivity to about P pi = 170 kPa, which is equivalent to the pressure required for inducing phase difference of pi rad between the TE and TM polarizations. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).
We demonstrate theoretically the electric tunability due to the coalescence of exceptional points in PT-symmetric waveguides bounded by imperfect conductive layers. Owing to the competition effect of multimode interac...
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We demonstrate theoretically the electric tunability due to the coalescence of exceptional points in PT-symmetric waveguides bounded by imperfect conductive layers. Owing to the competition effect of multimode interaction, multiple exceptional points and PT phase transitions could be attained in such a simple system, and their occurrences are strongly dependent on the boundary conductive layers. When the conductive layers becomevery thin, it is found that the oblique transmittance and reflectance of the same system can be tuned between zero and one by a small change in the carrier density. The results may provide an effective method for fast tuning and modulation of optical signals through electrical gating. (C) 2017 Optical Society of America
We study wave transmission G through quasi-one-dimensional waveguides with constant cross section. Constant cross section means that an infinite set of lines of the same length (that do not intersect each other) which...
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We study wave transmission G through quasi-one-dimensional waveguides with constant cross section. Constant cross section means that an infinite set of lines of the same length (that do not intersect each other) which are perpendicular to one boundary of the waveguide are also perpendicular to the other boundary. This makes the sign of the tangential velocity for all collision points of an arbitrary particle trajectory to stay constant, so that the classical or ray dynamics in the waveguide is unidirectional. In particular, we report the systematic enhancement of transmission in unidirectional corrugated waveguides when contrasting their transmission properties with those for equivalent constant-width waveguides (for which the classical dynamics is not unidirectional since particles moving in one direction along the waveguide can change its direction of motion). Also, we verify the universality of the distribution of transmissions P(G) in the diffusive ( G > 1) and localized ( G << 1) regimes of transport. Moreover, we show that in the transition regime, G similar to 1, P(G) is well described by the DMPK approach (the Fokker-Planck approach of Dorokhov, Mello, Pereyra, and Kumar) to bulk-disordered wires.
The plasmonic bowtie antenna constantly attracts researchers' interests recently. In this paper, we design and demonstrate polarization sensitive and ultra-broadband excitations of plasmonic waveguides. The struct...
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The plasmonic bowtie antenna constantly attracts researchers' interests recently. In this paper, we design and demonstrate polarization sensitive and ultra-broadband excitations of plasmonic waveguides. The structure is composed of a bowtie aperture aligned near a stripe waveguide, which is fabricated on a single silver layer on top of a silica substrate. The dependence of resonance spectra on the arm length of the bowtie aperture is simulated. Only when the incident polarization is parallel to the waveguide direction, the plasmonic bound modes can be correctly excited. Importantly, an extremely wide spectrum bandwidth of 610 nm which covers most of the visible region from 500 nm till the near infrared light of 1 mu m is achieved. Our investigations will have intensive applications in next-generation plasmonic integrated chips and functional devices.
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