Structural design of mid-infrared waveguide detectors based on InAs/GaAsSb superlattice

In the realm of near-infrared spectroscopy,the detection of molecules has been achieved using on-chip waveguides and resonators.In the mid-infrared band,the integration and sensitivity of chemical sensing chips are often constrained by the reliance on off-chip light sources and detectors.In this study,we demonstrate an InAs/GaAsSb superlattice mid-infrared waveguide integrated detector.The GaAsSb waveguide layer and the InAs/GaAsSb superlattice absorbing layer are connected through evanescent coupling,facilitating efficient and highquality detection of mid-infrared light with minimal loss.We conducted a simulation to analyze the photoelectric characteristics of the device.Additionally,we investigated the factors that affect the integration of the InAs/GaAs⁃Sb superlattice photodetector and the GaAsSb waveguide.Optimal thicknesses and lengths for the absorption lay⁃er are determined.When the absorption layer has a thickness of 0.3μm and a length of 50μm,the noise equiva⁃lent power reaches its minimum value,and the quantum efficiency can achieve a value of 68.9%.The utilization of waveguide detectors constructed with Ⅲ-Ⅴ materials offers a more convenient means of integrating mid-infra⁃red light sources and achieving photoelectric detection chips.

Singular optical propagation properties of two types of one-dimensional anti-PT-symmetric periodic ring optical waveguide networks

Two types of one-dimensional(1D)anti-PT-symmetric periodic ring optical waveguide networks,consisting of gain and loss materials,are constructed.The singular optical propagation properties of these networks are investigated.The results show that the system composed of gain materials exhibits characteristics of ultra-strong transmission and bidirectional reflection.Conversely,the system composed of loss materials demonstrates equal transmittance and reflectance at some frequencies.In both the systems,a new type of total reflection phenomenon is observed.When the imaginary part of the refractive indices of waveguide segments is smaller than 10-5,the system shows bidirectional transparency with the transmittance tending to be 1 and reflectivity to be smaller than 10-8 at some bands.When the refractive indices of the waveguide segments are real,the system will be bidirectional transparent at the full band.These findings may deepen the understanding of anti-PT-symmetric optical systems and optical waveguide networks,and possess potential applications in efficient optical energy storage,ultra-sensitive optical filters,ultra-sensitive all-optical switches,integrated optical chips,stealth physics,and so on.

Simultaneous guidance of electromagnetic and elastic waves via glide symmetry phoxonic crystal waveguides

A phoxonic crystal waveguide with the glide symmetry is designed,in which both electromagnetic and elastic waves can propagate along the glide plane at the same time.Due to the glide symmetry,the bands of the phoxonic crystal super-cell degenerate in pairs at the boundary of the Brillouin zone.This is the so-called band-sticking effect and it causes the appearance of gapless guided-modes.By adjusting the magnitude of the glide dislocation the edge bandgaps,the bandgap of the guided-modes at the boundary of the Brillouin zone,can be further adjusted.The photonic and phononic guided-modes can then possess only one mode for a certain frequency with relatively low group velocities,achieving single-mode guided-bands with relatively flat dispersion relationship.In addition,there exists acousto-optic interaction in the cavity constructed by the glide plane.The proposed waveguide has potential applications in the design of novel optomechanical devices.

Single-photon scattering and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system

We theoretically investigate coherent scattering of single photons and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system.Using the real-space Hamiltonian,analytical expressions are derived for the transport spectra scattered by these two giant atoms with four azimuthal angles.Fano-like resonance can be exhibited in the scattering spectra by adjusting the azimuthal angle difference.High concurrence of the entangled state for two atoms can be implemented in a wide angle-difference range,and the entanglement of the atomic states can be switched on/off by modulating the additional azimuthal angle differences from the giant atoms.This suggests a novel handle to effectively control the single-photon scattering and quantum entanglement.

Unveiling the in-plane anisotropic dielectric waveguide modes in α-MoO_(3) flakes

The unique in-plane and out-of-plane anisotropy of α-MoO_(3) has attracted considerable interest with regard to potential optoelectronic applications. However, most research has focused on the mid-infrared spectrum, leaving its properties and applications in the visible and near-infrared light spectrum less explored. This study advances the understanding of waveguiding properties of α-MoO_(3) by near-field imaging of the waveguide modes along the [100] and [001] directions of α-MoO_(3) flakes at 633 nm and 785 nm. We investigate the effects of flake thickness and documented the modes' dispersion relationships, which is crucial for tailoring the optical responses of α-MoO_(3) in device applications. Our findings enhance the field of research into α-MoO_(3), highlighting its utility in fabricating next-generation optoelectronic devices due to its unique optically anisotropic waveguide.

Selective Impact of Dispersion and Nonlinearity on Waves and Solitary Wave in a Strongly Nonlinear and Flattened Waveguide

The waveguide which is at the center of our concerns in this work is a strongly flattened waveguide, that is to say characterized by a strong dispersion and in addition is strongly nonlinear. As this type of waveguide contains multiple dispersion coefficients according to the degrees of spatial variation within it, our work in this article is to see how these dispersions and nonlinearities each influence the wave or the signal that can propagate in the waveguide. Since the partial differential equation which governs the dynamics of propagation in such transmission medium presents several dispersion and nonlinear coefficients, we check how they contribute to the choices of the solutions that we want them to verify this nonlinear partial differential equation. This effectively requires an adequate choice of the form of solution to be constructed. Thus, this article is based on three main pillars, namely: first of all, making a good choice of the solution function to be constructed, secondly, determining the exact solutions and, if necessary, remodeling the main equation such that it is possible;then check the impact of the dispersion and nonlinear coefficients on the solutions. Finally, the reliability of the solutions obtained is tested by a study of the propagation. Another very important aspect is the use of notions of probability to select the predominant solutions.

Active Cancelation of Acoustic Noise in Waveguides by Standard Control Task Decision Usage

Cybernetic decision variants were analyzed in order to use for physical task of active noise cancelation. 10 dB mean active noise cancellation is demonstrated in two decades frequency band by usage of cybernetic decision for acoustical duct physical scale model. The used decision was found on minimization of acoustical field power transfer function from the beginning of waveguide to their end.

Influence of Waveguide Properties on Wave Prototypes Likely to Accompany the Dynamics of Four-Wave Mixing in Optical Fibers

In this article, we study the impacts of nonlinearity and dispersion on signals likely to propagate in the context of the dynamics of four-wave mixing. Thus, we use an indirect resolution technique based on the use of the iB-function to first decouple the nonlinear partial differential equations that govern the propagation dynamics in this case, and subsequently solve them to propose some prototype solutions. These analytical solutions have been obtained;we check the impact of nonlinearity and dispersion. The interest of this work lies not only in the resolution of the partial differential equations that govern the dynamics of wave propagation in this case since these equations not at all easy to integrate analytically and their analytical solutions are very rare, in other words, we propose analytically the solutions of the nonlinear coupled partial differential equations which govern the dynamics of four-wave mixing in optical fibers. Beyond the physical interest of this work, there is also an appreciable mathematical interest.

Waveguide Bragg Grating for Fault Localization in PON

Femtosecond laser direct inscription is a technique especially useful for prototyping purposes due to its distinctive advantages such as high fabrication accuracy,true 3D processing flexibility,and no need for mold or photomask.In this paper,we demonstrate the design and fabrication of a planar lightwave circuit(PLC)power splitter encoded with waveguide Bragg gratings(WBG)using a femtosecond laser inscription technique for passive optical network(PON)fault localization application.Both the reflected wavelengths and intervals of WBGs can be conveniently tuned.In the experiment,we succeeded in directly inscribing WBGs in 1×4 PLC splitter chips with a wavelength interval of about 4 nm and an adjustable reflectivity of up to 70% in the C-band.The proposed method is suitable for the prototyping of a PLC splitter encoded with WBG for PON fault localization applications.

Accurate analysis of arbitrarily-shaped helical groove waveguide

This paper presents a theory on accurately analysing the dispersion relation and the interaction impedance of electromagnetic waves propagating through a helical groove waveguide with arbitrary groove shape, in which the complex groove profile is synthesized by a series of rectangular steps. By introducing the influence of high-order evanescent modes on the connection of any two neighbouring steps by an equivalent susceptance under a modified admittance matching condition, the assumption of the neglecting discontinuity capacitance in previously published analysis is avoided, and the accurate dispersion equation is obtained by means of a combination of field-matching method and admittancematching technique. The validity of this theory is proved by comparison between the measurements and the numerical calculations for two kinds of helical groove waveguides with different groove shapes.

Double-Teeth-Shaped Plasmonic Waveguide Electro-Optical Switches

An electro-optical switch based on a plasmonic T-shaped waveguide structure with a double-teeth-shaped waveguide filled with 4-dimethylamino-N-methyl-4-stilbazolium tosylate is proposed and numerically investigated.The Finite-difference time domain simulation results reveal that the structure can operate as a circuit switch by controlling the external voltages V1 and/or V_(2).The proposed structure can also operate as a variable optical attenuator,which can continuously attenuate the power of a light beam from 6 dB to 30 dB by an external electrical field.The structure is of small size of a few hundred nanometers.Our results may open a possibility to construct nanoscale high-density photonic integration circuits.

High-Efficiency Quantum Routing in a Multi-Cross-Shaped Waveguide

Efficiently routing the quantum signals between different channels is essential in a quantum multichannel network.We investigate the quantum routing in a multi-cross-shaped waveguide coupled to driven three-level systems.Numerical results show that the high routing capacity transferring from the input channel to the other channels can be explicitly enhanced by effective reflection potentials. The proposed system may be utilized as a scalable quantum device to control single-photon routing.

Bidirectional highly-efficient quantum routing in a T-bulge-shaped waveguide

Quantum routing in a T-bulge-shaped waveguide system coupled with a driven cyclic three-level atom and a twolevel atom is investigated theoretically.By employing the discrete-coordinate scattering method,exact expressions of the transport coefficients along three ports of the waveguide channels are derived.Our results show that bidirectional high transfer-rate single-photon routing between two channels can be effectively implemented,with the help of the effective potential generated by two atoms and the external driving.Moreover,multiple band zero-transmission emerges in the scattering spectra,arising from the quantum interferences among photons scattered by the boundary and the bulged resonators.The proposed system may suggest an efficient duplex router with filtering functions.

Resonance and Antiresonance in Electronic Transport Process Through a T-Shaped Quantum Waveguide

By means of the transfer matrix approach, the linear conductance spectrum for electronic transport through a T-shaped quantum waveguide is calculated. The resonant peaks and the antiresonant dips in the conductance spectrum are mainly focused. The previous prediction about their positions by other theoretical approaches is checked. In addition, a function of spin filtering is suggested based on the interplay of the resonance and antiresonance in this T-shaped quantum waveguide.

Novel high-quality Fano resonance based on metal-insulator-metal waveguide with L-shaped resonators

Developing a convenient method that can be routinely applied for ascertaining proportions of different vegetable oils employed in commercial blended edible oils remains a significant challenge.We address this issue by proposing a novel method for detecting volume fraction of different oils based on the fact that these oils are optically transparent and have slightly different indices of refraction at a given temperature and wavelength.Accordingly,we develop a highly sensitive sensor for measuring the index of refraction of oil blends based on Fano resonance spectra obtained using a metal-insulatormetal(MIM)waveguide structure comprising a gapped straight waveguide coupled with two L-shaped resonators.The index of refraction sensitivity and figure of merit of the structure are calculated based on modeling using the finite element method,and the waveguide structure is accordingly optimized by adjusting the different geometric parameters to achieve a high-quality Fano resonance spectrum.The optimized structure achieves an ultra-high refractive index sensitivity of 770 nm/RIU in terms of a refractive index unit(RIU)of 1.Moreover,a highly stable linear relationship is obtained between the refractive index of mixed edible oils and the resonance wavelength.Experimental results demonstrate that the proposed structure can detect slight changes in the volume fractions of the components in blended oils.

STUDY ON RECTANGULAR WAVEGUIDE GRATING SLOW-WAVE STRUCTURE WITH COSINE-SHAPED GROOVES

This paper focuses on a new rectangular waveguide grating Slow-Wave Structure (SWS) with cosine-shaped grooves and studies the propagation characteristics of the wave in the SWS. By using the approximate field-matching conditions,the dispersion equation and the coupling impedance of this circuit are obtained. The dispersion curves and coupling impedances of the fundamental wave are calculated and the influences of the various geometrical dimensions are discussed. The results show that the bandwidth of the cosine-shaped groove SWS is much wider than that of rectangular-shaped groove one. And reducing the groove width can broaden the frequency-band and decrease the phase-velocity,while increment of the groove-depth can also decrease phase-velocity. For above cases,the coupling impedance is more than 16Ω. The present analysis will be helpful on further study and design of the RF systems used in millimeter wave Traveling Wave Tube (TWT).

Independently tunable dual resonant dip refractive index sensor based on metal–insulator–metal waveguide with Q-shaped resonant cavity

A plasmonic resonator system consisting of a metal–insulator–metal waveguide and a Q-shaped resonant cavity is proposed in this paper. The transmission properties of surface plasmon polaritons in this structure are investigated by using the finite difference in time domain(FDTD) method, and the simulation results contain two resonant dips. The physical mechanism is studied by the multimode interference coupled mode theory(MICMT), and the theoretical results are in highly consistent with the simulation results. Furthermore, the parameters of the Q-shaped cavity can be controlled to adjust the two dips, respectively. The refractive index sensor proposed in this paper, with a sensitivity of 1578 nm/RIU and figure of merit(FOM) of 175, performs better than most of the similar structures. Therefore, the results of the study are instructive for the design and application of high sensitivity nanoscale refractive index sensors.

Non-Markovianity of an atom in a semi-infinite rectangular waveguide

We investigate the non-Markovianity(NM)of a waveguide QED with a two-level atom as the system and a semiinfinite rectangular waveguide as the environment,where the transverse magnetic(TM_(mn))modes define the quantum channels of guided photons.The perfect mirror imposed by the finite end exerts a retarded feedback mechanism to allow for information backflow,which leads to NM dynamics.For the energy separation of the atom far away from the cutoff frequencies of transverse modes,the delay differential equations are obtained with single-excitation initial in the atom.Our attention is focused on the effects of multiple quantum channels involved in guiding photons on the degree of nonMarkovian behavior.An asymptotic value of the non-Markovianity N_(1)can be found as the atom–mirror distance is large enough,however,the asymptotic value of N_(2)of the atom interacting with the effective double-modes is lower than that of the atom interacting with the effective single-mode.We also show that N_(1)is a constant,and the analytical expression for N_(2)is related to the parameters associated with the modes,which is related to the interference of the two modes.

A Substrate Integrated Waveguide Based Filtenna for X and Ku Band Application

In this paper Substrate Integrated Waveguide-basedfiltenna operating at Ku band is proposed.The model is designed on a low loss dielectric substrate having a thickness of 0.508 mm and comprises of shorting vias along two edges of the substrate walls.To realize a bandpassfilter,secondary shorting vias are placed close to primary shorting vias.The dimension and position of the vias are carefully analyzed for Ku band frequencies.The model is fabricated on Roger RT/duroid 5880 and the performance characteristics are measured.The proposed model achieves significant impedance characteristics with wider bandwidth in the Ku band.The model also achieves a maximum gain of 7.46 dBi in the operating band thus making it suitable for Ku-band applications.Substrate Integrated Waveguide(SIW)Structures possess most of the advantages over conventional radiofrequency waveguides since they have high power management capacity with self-consistent electrical shielding.The most noteworthy advantage of SIW,it can able to integrate all the components on the same substrate,both passive and active components.

Generation of hyperentangled photon pairs based on lithium niobate waveguide

Generation of hyperentangled photon pairs is investigated based on the lithium niobate straight waveguide.We propose to use the nonlinear optical process of spontaneous parametric down-conversion(SPDC)and a well-designed lithium niobate waveguide structure to generate a hyperentangled(in the polarization dimension and the energy-time dimension)two-photon state.By performing numerical simulations of the waveguide structure and calculating the possible polarization states,joint spectral amplitudes(JSA),and joint temporal amplitudes(JTA)of the generated photon pair,we show that the generated photon pair is indeed hyperentangled in both the polarization dimension and the energy-time dimension.