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.

All polymer asymmetric Mach-Zehnder interferometer waveguide sensor by imprinting bonding and laser polishing

We present an all polymer asymmetric Mach-Zehnder interferometer （AMZI） waveguide sensor based on imprinting bonding and laser polishing method. The fabrication methods are compatible with high accuracy waveguide sensing structure. The rectangle waveguide structure of this sensor has three sensing surfaces contacting the test media, and its sensing accuracy can be increased 5 times compared with that of one surface sensing structure. An AMZI device structure is designed. The single mode condition, the length of the sensing arm, and the length deviation between the sensing arm and the reference arm are optimized. The length deviation is optimized to be 19.8 μm in a refractive index range between 1.470 and 1.545. We fabricate the AMZI waveguide by lithography and wet etching method. The imprinting bonding and laser polishing method is proposed and investigated. The insertion loss is between-80.36 dB and-10.63 dB. The average and linear sensitivity are 768.1 dB/RIU and 548.95 dB/RIU, respectively. And the average and linear detection resolution of the sensor are 1.3010-6 RIU （RIU：refractive index unit） and 1.8210-5 RIU, respectively. This sensor has a fast and cost-effective fabrication process which can be used in the cases of requiring portability and disposability.

Mach-Zehnder Type Annealed Proton Exchange Waveguide and Coplanar Waveguide Modulation Electrode LiNbO_3 Intensity Modulator

The characteristics of a conventional LiNbO3 intensity modulator made up of a Mach-Zehnder(MZ) type annealed proton exchange(APE) waveguide and coplanar waveguide(CPW) modulation electrode are presented. The APE waveguide characteristics and their relations with process parameters are analyzed. At the same time, the electrical characteristics of modulation electrode, such as modulation voltage, microwave effective index associated with modulation bandwidth, characteristics impedance, are also investigated in detail.

Structure optimization of polymeric Mach-Zehnder rib waveguide

A systematic analysis of the polymeric Mach-Zehnder rib waveguide is presented based on the calculation and optimization. The simulation is carried out with the Effective Index Method (EIM) and two-dimensional (2-D) Finite Difference Beam Propagation Method (FD-BPM). The large refractive index step between the consecutive polymer layers is reduced by using EIM and thus the precision of the calculation is ensured. The important param- eters of the waveguide such as Y-junction angle and the separation gap are discussed and their relationships with the optical power propagation and the loss characteristics are investigated in this paper. The total loss of the opti- mized structure is 0.258 dB.

基于Mach-Zehnder干涉装置的散射体偏振特性研究

根据偏振度测量原理推导了相干矩阵中各个参数的测量公式,主要是复参量的实部与虚部.基于Mach-Zehnder干涉装置搭建了散射体偏振度测试平台,并对同一粒径不同浓度散射体的偏振特性进行了测试.结果表明:浓度为0.00625%的聚苯乙烯(Polystyrene,PS)散射介质光散射较弱,偏振度值高达0.992,散射体具有良好的保偏特性;随着聚苯乙烯散射介质浓度增大到0.025%,光散射增强,偏振度值降至0.545,散射体的退偏效果显著.

基于Mach-Zehnder干涉仪的自相似激光器压缩系统设计

为了研究自相似脉冲在Mach-Zehnder干涉仪的压缩特性,采用非线性薛定谔方程对自相似脉冲的演化和压缩进行了模拟,分析了基于级联单模光纤的Mach-Zehnder干涉仪的光纤参数对脉冲压缩的影响。结果表明,在不考虑高阶色散的情况下,当上臂的两种单模光纤长度分别为8.16 m和2.16 m、下臂的单模光纤长度为8.16 m时,获得半峰全宽为27.85 fs、峰值功率为1860.59 W、基座能量比例为10.241%的最佳压缩脉冲;考虑高阶色散时,脉冲在单模光纤中传输呈现出峰值功率增大、基座增大的现象,且脉冲右移不利于输出基座较小的压缩脉冲;当3阶色散系数小于0.001 ps^(3)/km时,利用Mach-Zehnder干涉仪来压缩能获得质量较好的飞秒脉冲。该研究结果对于自相似脉冲的压缩研究具有一定的参考价值。

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.

Highly Efficient Two-Channel Drop Filter of Single Photons with One Drop Waveguide

A novel double-channel drop filter of single photons with only a drop waveguide is proposed. In the structure, two microresonators with a qubit are used to connect the drop waveguide and the bus waveguide with a reflector. By tuning the system parameters, multiple wavelengths with high drop efficiencies in two output channels of the drop waveguide are obtained. As the reflector is independent on its exact location, and one drop waveguide with two drop channels saves the integrated space, this may suggest a potential filtering device which functions in photonic integrated circuits and dense wavelength division multiplexing communication.

Spontaneous emission of a moving atom in a waveguide of rectangular cross section

We study the spontaneous emission(SE) of an excited nonrelativistic two-level system(TLS) interacting with the vacuum in a waveguide of rectangular cross section. All TLS’s transitions and the center-of-mass motion of the TLS are taken into account. The SE rate and the carried frequency of the emitted photon for the TLS initially being at rest are obtained, it is found that in the first order of the mass M, the frequency of the emitted photon is smaller than the transition frequency of the TLS and the SE rate is smaller than the SE rate Γfof the TLS fixed in the same waveguide. The SE rate for the TLS initially being moving is obtained in the second order of the mass M. The SE rate is smaller than Γfbut it is dependent not only on the atomic mass but also on the initial momentum. The carried frequency of the emitted photon is decreased when it travels along the direction of the initial momentum, whereas it is increased when it travels in the opposite direction of the initial momentum.

Degenerate polarization entangled photon source based on a single Ti-diffusion lithium niobate waveguide in a polarization Sagnac interferometer

Combining a Ti-diffusion periodically poled lithium niobate(PPLN)waveguide with a Sagnac interferometer,two opposite directions type-II spontaneous parametric down conversions(SPDC)occur coherently and yield a high brightness,high stability polarization entanglement source.The source produces degenerate photon pairs at 1540.4 nm with a brightness of B=(1.36±0.03)×10^(6) pairs/(s·nm·m W).We perform quantum state tomography to reconstruct the density matrix of the output state and obtain a fidelity of F=0.983±0.001.The high brightness and phase stability of our waveguide source enable a wide range of quantum information experiments operating at a low pump power as well as hold the advantage in mass production which can promote the practical applications of quantum technologies.