Effects Of Fabrication Errors Research Articles

Design of photonic crystal fiber supporting 190 orbital angular momentum modes with low nonlinearity coefficient

A new photonic crystal fiber is proposed for the transmission of more orbital angular momentum modes with a rectangular air hole arrangement to increase the cladding air-filling rate. The results reveal that the fiber can support 190 orbital angular momentum modes in the C+L band, with the topological charge ordering up to 48, and the effective refractive index difference between adjacent eigenmodes is above 10−3. The effective mode area of all the eigenmodes is larger than 208.02 μm2, the nonlinearity coefficient is less than 0.43 W−1∙km−1, the confinement loss reaches up to 10−12-10−8 dB/m, the dispersion is flat and the minimum dispersion change is 3.15 ps∙nm−1∙km−1, with mode purity greater than 97.4%. Compared to existing typical orbital angular momentum transmission photonic crystal fibers, this fiber can support more orbital angular momentum modes for most purposes with lower nonlinearity coefficient, higher mode purity, better propagation characteristics but simpler structure. The highest nonlinearity coefficient is reduced by at least 0.3 W−1∙km−1 compared to existing typical orbital angular momentum transmission photonic crystal fibers. The effect of fabrication errors on the transmission quality of orbital angular momentum modes is also discussed, and the results reveal that the effect on mode transmission quality is small at 1–2% variations of air holes. Therefore, this photonic crystal fiber is promising in high-capacity communication systems.

Two Individual Super-Bound State Modes within Band Gap with Ultra-High Q Factor for Potential Sensing Applications in the Terahertz Wave Band.

Bound states in the continuum (BICs) garnered significant research interest in the field of sensors due to their exceptionally high-quality factors. However, the wide-band continuum in BICs are noise to the bound states, and it is difficult to control and filter. Therefore, we constructed a top-bottom symmetric cavity containing three high permittivity rectangular columns. The cavity supports a symmetry-protected (SP) superbound state (SBS) mode and an accidental (AC) SBS mode within the bandgap. With a period size of 5 × 15, the bandgap effectively filters out the continuum, allowing only the bound states to exist. This configuration enabled us to achieve a high signal-to-noise ratio and a wide free-spectral-range. The AC SBS and the SP SBS can be converted into quasi-SBS by adjusting different parameters. Consequently, the cavity can function as a single-band sensor or a dual-band sensor. The achieved bulk sensitivity was 38 µm/RIU in terahertz wave band, and a record-high FOM reached 2.8 × 108 RIU-1. The effect of fabrication error on the performance for sensor application was also discussed, showing that the application was feasible. Moreover, for experimental realization, a 3D schematic was presented. These achievements pave the way for compact, high-sensitivity biosensing, multi-wavelength sensing, and other promising applications.

Research on Structural Failure of MEMS Safety and Arming Device Considering Uncertainty in Fabrication Errors

This paper presents an efficient methodology for assessing the structural failure of microelectromechanical systems (MEMS) used in safety and arming devices (SAD) while taking into account the effect of fabrication errors. The proposed methodology uses statistical characteristics that are assessed using non-intrusive polynomial chaos expansion (PCE) to consider uncertainty. The effectiveness of the methodology is demonstrated by considering the example of the latching feature in MEMS SAD, and comparing the results with experimental data obtained from a fabricated prototype. The proposed methodology accurately determines the failure probability and sensitive parameters of the sample, and provides insights into the impact of fabrication errors on the structural failure of the sample. It achieves the objective of reducing the burden of repetitive finite element analysis (FEA) in uncertainty analysis, and provides an efficient way to account for uncertainty in the study of MEMS devices.

The Effect of Fabrication Error on the Performance of Mid-Infrared Metalens with Large Field-of-View.

Mid-infrared large field-of-view (FOV) imaging optics play a vital role in infrared imaging and detection. The metalens, which is composed of subwavelength-arrayed structures, provides a new possibility for the miniaturization of large FOV imaging systems. However, the inaccuracy during fabrication is the main obstacle to developing practical uses for metalenses. Here, we introduce the principle and method of designing a large FOV doublet metalens at the mid-infrared band. Then, the quantitative relationship between the fabrication error and the performance of the doublet metalens with a large FOV from four different fabrication errors is explored by using the finite-difference time-domain method. The simulation results show that the inclined sidewall error has the greatest impact on the focusing performance, and the interlayer alignment error deforms the focusing beam and affects the focusing performance, while the spacer thickness error has almost no impact on the performance. The contents discussed in this paper can help manufacturers determine the allowable processing error range of the large FOV doublet metalens and the priority level for optimizing the process, which is of significance.

Influencing Effects of Fabrication Errors on Performances of the Dielectric Metalens.

Despite continuous developments of manufacturing technology for micro-devices and nano-devices, fabrication errors still exist during the manufacturing process. To reduce manufacturing costs and save time, it is necessary to analyze the effects of fabrication errors on the performances of micro-/nano-devices, such as the dielectric metasurface-based metalens. Here, we mainly analyzed the influences of fabrication errors in dielectric metasurface-based metalens, including geometric size and shape of the unit element, on the focusing efficiency and the full width at half maximum (FWHM) values. Simulation results demonstrated that the performance of the metasurface was robust to fabrication errors within a certain range, which provides a theoretical guide for the concrete fabrication processes of dielectric metasurfaces.

Accurate Self-Configuration of Rectangular Multiport Interferometers

Multiport interferometers based on integrated beamsplitter meshes are widely used in photonic technologies. While the rectangular mesh is favored for its compactness and uniformity, its geometry resists conventional self-configuration approaches, which are essential to programming large meshes in the presence of fabrication error. Here, we present a new configuration algorithm, related to the $2\times 2$ block decomposition of a unitary matrix, that overcomes this limitation. Our proposed algorithm is robust to errors, requires no prior knowledge of the process variations, and relies only on external sources and detectors. We show that self-configuration using this technique reduces the effect of fabrication errors by the same quadratic factor observed in triangular meshes. This relaxes a significant limit to the size of multiport interferometers, removing a major roadblock to the scaling of optical quantum and machine-learning hardware.

High-Q photonic crystal cavities for nanolasers on patterned silicon-on-insulator substrates

As the performance of the silicon-based nanolaser is developing, further miniaturization of laser size is expected, and nanocavities will make it possible to avoid defects contained in the gain cavity. Hence, the miniaturization of the cavity is becoming necessary. In this letter, a photonic crystal cavity for the nanolaser grown on the patterned SOI substrate was proposed and analyzed in detail. The quality (Q) factor of 5 × 105 at a resonant wavelength of 1.516μm was demonstrated. And an insight into the variation of the resonant wavelength and the dependence of the Q-factor on the geometrical parameters of the laser cavity was obtained through simulation. For current injection, a pillar under the cavity region was introduced, the Q-factor over 104 was obtained as the length of the pillar was less than 160 nm. The effects of fabrication errors on the performance of cavities were also discussed by simulation.

Randomly aperiodically poled LiNbO3 crystal design by Monte Carlo–Metropolis with simulated annealing optimization for ultrabroadband photon pair generation

We report a scheme for generating ultrabroadband two-photon states by spontaneous parametric downconversion (SPDC) using randomly aperiodically poled crystals designed with an optimization algorithm based on the Monte Carlo-Metropolis method with simulated annealing. A particular SPDC source is discussed, showing results of the spectral and temporal properties of the emitted two-photon states, obtaining almost transform-limited SPDC biphoton wave packets. We also analyze the effect of fabrication errors on the SPDC.

Optimization of the silicon-based aperiodic optical phased array antenna.

Beam engineering is one of the most important functionalities in light detection and ranging (LiDAR). In this work, a silicon optical phased array (OPA) is employed to control the beam profile. Machine-learning-based genetic algorithm optimization is utilized to suppress the sidelobes of the far field pattern assuming the random distribution of aperiodic arrays. The optimized mainlobe position versus wavelength relationship in two-dimensional aperiodic arrays is distinctly different from prior works. Analysis was performed to show the effect of fabrication error of arrays on the side mode suppression ratio. Our study provides an effective pathway to optimize the random distributed OPAs within a controllable time frame among the vast number of parameters.

Measurement of optical characteristics of catadioptric retroreflectors

A technique for determining the effective scattering area of retroreflective catadioptric (reflective–refractive) devices is presented. An experimental setup for measuring the effective scattering area and comparative calculated and measurement data on the effect of fabrication errors on the characteristics of retroreflective elements are presented.

In-situ computed tomography investigation of the compression behaviour of strut, and periodic surface lattices

In this work the effects of fabrication errors in the Body Centered Cubic strut lattice, and the periodic surface lattice Schwarz Diamond has been investigated. The lattices were both fabricated as-is and with induced errors to evaluate the lattices response to fabrication errors. The behaviour of the lattices were studied using compression test and in-situ computed tomography investigation. The results show that the Schwarz Diamond lattices in general are stronger than the Body Centered Cubic lattices in all of the measured aspects. Often up to five times stronger. It was also found that the elastic behaviour of the Schwarz Diamond lattices were mainly unaffected by fabrication errors while the Body Centered Cubic lattices experienced severe losses in performance. The behaviour of the lattices under compression could be followed using computed tomography which aided in the understanding of their behaviour.

Aberration correction of Fresnel zone lenses telescope based on adaptive optics system

Fresnel zone lens (FZL) telescope is attracting increasing attention owing to its small volume and light weight. However, depending on the fabrication method of FZL, the linewidth and etch depth of FZL may deviate from the set value. It must be considered that the performance of the FZL is influenced by aberrations generated during manufacture. We simulate the effect of fabrication errors on optical performance of FZL and find that the linewidth error of FZL structure is the main cause of image degradation. In addition, we provide a method for correcting aberrations of FZL telescope with adaptive optics system (AOS). This method is verified by the experimental system. The results show that the image resolution is successfully improved after AO correction. The full-width, half-maximum value of a far-field image is improved from 0.065 to 0.038λ. The peak value of image energy after correction has increased by 4.23 times.

Effects of fabrication errors on the focusing performance of a sector metalens

Using e-beam lithography, a 16-sector spiral metalens was fabricated in an amorphous silicon, capable of converting linearly polarized incident light into an azimuthally polarized optical vortex. When illuminated by a 633-nm linearly polarized laser beam, the metalens generated a near-surface subwavelength focal spot equal to 0.75 of the incident wavelength at full-width of half-maximum intensity. The focusing performance of the spiral metalens was numerically shown to be sensitive to the deviation of the factual microrelief from the calculated height. For the designed microrelief height, a circularly polarized incident beam was focused into a bright ring with a reverse energy flow occurring at its center. For the microrelief height other than the designed one, the energy backflow effect did not occur.

Diffraction symmetry of binary Fourier elements with feature sizes on the order of the illumination wavelength and effects of fabrication errors

When building spot array binary Fourier diffractive optical elements (DOEs) having feature sizes on the order of the wavelength, we noticed remarkable variations in the experimental diffraction efficiency compared to the simulation results. Even with the use of high-cost electron beam lithography and rigorous Fourier modal method simulations, there appear to be no publications, to the best of our knowledge, showing close agreement in diffraction efficiency between the simulation and experimental results. In this Letter, we show that the diffraction symmetry of binary Fourier DOEs can be an efficient and consistent metric for evaluating the limit of the thin-element approximation and the effects of fabrication errors.

Robust quantum entanglement generation and generation-plus-storage protocols with spin chains

Reliable quantum communication/processing links between modules are a necessary building block for various quantum processing architectures. Here we consider a spin chain system with alternating strength couplings and containing three defects, that impose three domain walls between topologically distinct regions of the chain. We show that -- in addition to its useful, high fidelity, quantum state transfer properties -- an entangling protocol can be implemented in this system, with optional localisation and storage of the entangled states. We demonstrate both numerically and analytically that, given a suitable initial product-state injection, the natural dynamics of the system produces a maximally entangled state at a given time. We present detailed investigations of the effects of fabrication errors, analyzing random static disorder both in the diagonal and off-diagonal terms of the system Hamiltonian. Our results show that the entangled state formation is very robust against perturbations of up to $\sim10\%$ the weaker chain coupling, and also robust against timing injection errors. We propose a further protocol which manipulates the chain in order to localise and store each of the entangled qubits. The engineering of a system with such characteristics would thus provide a useful device for quantum information processing tasks involving the creation and storage of entangled resources.

Comparison of Characteristics of Permanent-Magnet Linear Oscillating Actuator According to Laminated Method of Stator Core

The efficiency of a linear oscillating actuator (LOA) can be increased by reducing the mechanical losses caused by the crankshaft mechanism. In addition, this system has lower noise and fewer vibration effects than rotary motors. In this paper, the features of the stator core in an LOA are examined with regard to a new radial lamination method. When typical rotational equipment is used, the stator core is laminated toward the axis to reduce the eddy current losses. In contrast, the LOA should be laminated in a radial direction. Conventional radial lamination has a weakness when compared with axis lamination: the air gap has a low flux density owing to the small stacking factor. To address this problem, this paper suggests a new radial lamination method that laminates the teeth and yoke of the outer stator in a separated formation. Compared with the existing lamination model, the presenting lamination model multiplies the flux density of the air gap by enlarging the stacking factor. The results indicate that the present lamination model has higher back electromotive force and thrust. In addition, the effect of fabrication error is hardly observed when the new lamination method is applied. Thus, the results suggest that the capability of an LOA can be increased by employing the present lamination method.

Effects of fabrication errors on diffraction efficiency for a diffractive membrane

Effects of fabrication errors on diffraction efficiency for a diffractive membrane

双层BOE加工误差对衍射效率的影响分析

双层BOE加工误差对衍射效率的影响分析

双层BOE加工误差对衍射效率的影响分析

双层BOE加工误差对衍射效率的影响分析

Ultracompact resonator with high quality-factor based on a hybrid grating structure.

We numerically investigate the properties of a hybrid grating structure acting as a resonator with ultrahigh quality factor. This reveals that the physical mechanism responsible for the resonance is quite different from the conventional guided mode resonance (GMR). The hybrid grating consists of a subwavelength grating layer and an un-patterned high-refractive-index cap layer, being surrounded by low index materials. Since the cap layer may include a gain region, an ultracompact laser can be realized based on the hybrid grating resonator, featuring many advantages over high-contrast-grating resonator lasers. The effect of fabrication errors and finite size of the structure is investigated to understand the feasibility of fabricating the proposed resonator.