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.
This study investigates the fabrication process of Zn-diffused ridge waveguides in periodically poled magnesium-doped lithium niobate(PPMgO:LN).A controlled variable method is used to study the effects of diffusion temperature,diffusion time,ZnO film thickness,and barrier layer thickness on the surface domain depolarization and waveguide quality of PPMgO:LN.A special barrier layer is proposed that can automatically lift off from the sample surface,which increases the depth of Zn doping and reduces the surface loss of the waveguide.By optimizing the process parameters,we fabricate Zn-diffused PPMgO:LN ridge waveguides with a length of 22.80 mm and a period of 18.0μm.The above waveguides can make a second harmonic generation(SHG)at 775 nm with an output power of 90.20 mW by a pump power of 741 mW at 1550 nm.The corresponding conversion efficiency is 3.160%/W·cm2,and the waveguide loss is approximately 0.81 dB/cm.These results demonstrate that high-efficiency devices can be obtained through the fabrication process described in this paper.
An underwater acoustic propagation experiment was conducted in the Dongsha Sea to investigate the influence of upslope waveguide environments on sound propagation.The experiment revealed a significant attenuation of acoustic energy at the slope crest.A realistic waveguide environment model was established,and the parabolic equation theory was used to calculate the acoustic propagation loss,confirming the observed impact of the sloping environment on sound propagation.Ray tracing methods were further employed to discuss and analyze the mechanism behind the sharp decrease in acoustic energy.The results indicate that during upslope propagation in an environment with a negative sound speed gradient,the acoustic energy effectively reaching the slope crest varies significantly due to factors such as source depth,slope inclination,horizontal distance,and bottom sound speed.Shallower source depths,steeper slopes,and lower bottom sound speeds result in weaker acoustic energy propagation to the slope crest.Furthermore,compared to horizontal waveguides,increased horizontal distances in upslope waveguides lead to more pronounced acoustic energy attenuation.
We calculate numerically the optical chiral forces in rectangular cross-section dielectric waveguides for potential enantiomer separation.Our study considers force strength and time needed for separating chiral nanoparticles,mainly via quasi-TE guided modes at short wavelengths(405 nm)and the 90°-phase-shifted combination of quasi-TE and quasi-TM modes at longer wavelengths(1310 nm).Particle tracking simulations show successful enantiomer separation within two seconds.These results suggest the feasibility of enantiomeric separation of nanoparticles displaying sufficient chirality using simple silicon photonic integrated circuits,with wavelength selection based on the nanoparticle size.
Trivial elastic waveguides induced by line defects and nontrivial elastic waveguides protected by topological edge states have been extensively examined in planar waveguide systems.Despite these investigations,little is known about topologically protected bulk states and their resulting robust transmission properties,especially in nonplanar elastic waveguides with folded,curved,and twisted surfaces.Elastic Dirac waveguides with robust boundary-induced bulk states are presented.These states arise from the truncated boundaries of bulks with linear Dirac conical dispersions,differing from topologically protected edge states ensured by the bulk-edge correspondence.Experimental proof is provided,in which boundary-induced bulk states show robustly high-throughput transmissions along the waveguides,even with folded,curved,and twisted surfaces.These results not only open up new avenues for examining novel topological phenomena about bulk but also offer new platforms for developing topological devices with nonplanar surfaces.
This article presents advancements in an analytical mode-matching technique for studying electromagnetic wave propagation in a parallel-plate metallic rectangular waveguide.This technique involves projecting the solution onto basis functions and solving linear algebraic systems to determine scattering amplitudes.The accuracy of this method is validated via numerical assessments,which involve the reconstruction of matching conditions and conservation laws.The study highlights the impact of geometric and material variations on reflection and transmission phenomena in the waveguide.
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.
