Splitter Structure Research Articles

Design of Photonic Molecule-Based Multiway Beam Splitter/Coupler with Variable Division Ratio

An optical beam splitter is used for dividing an input optical beam into several separate beams with a specific power ratio. Usually, conventional optical beam splitters have bulky dimensions (many optical wavelengths) and a fixed dividing ratio, which significantly limit the design of new miniaturized optical devices and integrated optical circuits. We propose and investigate in detail a novel physical concept of a highly miniaturized (up to two working wavelengths) planar optical resonant splitter/coupler with a switching element comprising a photonic molecule (PM) pair dispersing input optical fluxes in multiple directions with a tailored power ratio. The structural design of the proposed splitter is based on a silicon-on-insulator (SOI) platform and composed of high-quality resonators in the form of electromagnetically coupled submicron-sized microcylinders. The control on the power division ratio and the selection of optical beam directions is realized by tuning the photonic splitter structure to the corresponding resonance of the PM supermode. Compared to known analogs, the proposed design is easy and cheap in fabrication. Because of its tiny dimensions, it is suitable for integration into a “System-on-a-chip” platform and can dynamically change the beam power division ratio by input wave-phase manipulation.

1 × 4 nano-pixel power splitter designed using an electric profile correlation coefficient monitor method

The power splitter is one of the fundamental elements in a photonic IC. Among various power splitter structures, nano-pixel-based ones have attracted attention in recent years because of their flexible design capability. As there is no rigid design rule in nano-pixel layout, typically, inverse design algorithms are employed to realize the target function. In inverse design, general criteria are needed during the design process, and one typical criterion is the excess loss, however, there are no specific criteria for mode field evaluation. When designing a 1 × N power splitter, considering the power balance among the N output ports is crucial, therefore, we propose a correlation coefficient method to evaluate the output electric field profile. In this study, we adopted vector criteria including both an excess loss and correlation coefficient method during the inverse design process. As a result, the simulated results show all four 0th order modes and the output power to be 24.490%, 24.494%, 24.494%, and 24.490% with a low excess loss of 0.1 dB.

Topological edge and corner states of valley photonic crystals with zipper-like boundary conditions

We present a stable valley photonic crystal (VPC) unit cell with C 3v symmetric quasi-ring-shaped dielectric columns and realize its topological phase transition by breaking mirror symmetry. Based on this unit cell structure, topological edge states (TESs) and topological corner states (TCSs) are realized. We obtain a new type of wave transmission mode based on photonic crystal zipper-like boundaries and apply it to a beam splitter assembled from rectangular photonic crystals (PCs). The constructed beam splitter structure is compact and possesses frequency separation functions. In addition, we construct a box-shaped triangular PC structures with zipper-like boundaries and discover phenomena of TCSs in the corners, comparing its corner states with those formed by other boundaries. Based on this, we explore the regularities of the electric field patterns of TESs and TCSs, explain the connection between the characteristic frequencies and locality of TCSs, which helps better control photons and ensures low power consumption of the system.

Investigations on the Splitter Structure to Improve the Aerodynamic Performance of Gas Turbine Exhaust Diffuser at Different Swirl Angles

Abstract To weaken the flow separation in the exhaust diffuser under real operating conditions and increase the static pressure recovery coefficient of the exhaust diffuser, an exhaust diffuser structure with splitters was proposed. Based on verifying the reliability of the numerical method, the paper numerically explores the influence of the height and width of the splitter on the aerodynamic performance of the exhaust diffuser under three different inlet swirl angles by solving three-dimensional Reynolds-Averaged Navier–Stokes (RANS). The results show that the introduction of the splitter structure into the exhaust diffuser can effectively suppress the separation vortex near the strut, improve the flow state at the exhaust diffuser outlet, and further increase the static pressure recovery coefficient of the exhaust diffuser. The optimal splitter structure can be obtained by comparing the effects of the splitter height and width on the static pressure recovery performance of the exhaust diffuser under different inlet swirl angles. When the inlet swirl angles are 16 degs, 28 degs, and 38 degs, compared with the original exhaust diffuser without splitters, the optimal splitter structure can increase the static pressure recovery coefficient of the exhaust diffuser by 0.036, 0.096, and 0.146, respectively, with a relative increase of 7.3%, 34.2%, and 76.2%. The introduction of the splitter structure helps to improve the aerodynamic performance of the exhaust diffuser.

PLC-Based Integrated Refractive Index Sensor Probe with Partially Exposed Waveguide

This paper proposes a simple, high-efficiency refractive index (RI) sensor, with a structure based on the planar lightwave circuit (PLC) probe type. The optical sensor has a 1 × 2 splitter structure with reference and sensing channels, each consisting of a U-shaped waveguide structure that is configured by connecting C bends. This design allows for the sensor device to have a probe structure wherein the surface interconnected with activity devices (i.e., an optical source and optical detector) is placed on one side. The reference channel is bent with a minimum optical loss, and the sensing channel has a bent structure, involving a C-bend waveguide with a maximum loss. The C-bend waveguide with a maximum loss is conformally aligned to have a trench structure with the same bending radius, designed to selectively expose the sidewall of the core layer. The local index contrast varies depending on the material in contact with the trench, resulting in a change in the optical output power of the waveguide. The sensitivity of the proposed sensor was 0 and 2070 μW/refractive index unit (RIU) for the reference and sensing channels, respectively, as the RI changed from 1.385 to 1.445 at a 1550 nm wavelength. These results suggest that the proposed structure enables efficient RI measurement through the use of a simple dip-type method.

Design and optimization of 1 × 2 and 1 × 4 Y-shaped beam splitters in GaSb-based 2D photonic crystals

In this paper, we investigate the structural design of beam splitters with high total transmission efficiency in the two-dimensional (2D) GaSb (Gallium Antimonide)-based photonic crystals, and several optimal structures for [Formula: see text] and [Formula: see text] Y-shaped beam splitters have been provided. Using our proposed alternating iteration algorithm, by introducing several microstructures in the bend and Y-shaped junction areas to achieve topology optimization, the design of Y-shaped beam splitters with high total transmission efficiency at 1550 nm makes great progress. The splitter structures are designed on 2D GaSb-based photonic crystals with a triangular lattice of air holes immersed in the GaSb. All designs are simulated numerically and analyzed by using the finite element method. The optimized structures of [Formula: see text] Y-shaped beam splitters show that our optimization technique is efficient and simple. And the total transmission efficiencies both over [Formula: see text] at output ports are obtained, which indicates that our method is relatively efficient to other methods in some related reports.

Spoof Surface Plasmon Polariton Endfire Antenna Possessing Bidirectional and Unidirectional Radiation Pattern

A simple approach is proposed to design a new type of endfire antenna, which simultaneously possesses bidirectional and unidirectional radiation pattern in wideband. By the dispersion engineering, different frequency bands spoof surface plasmon polariton (SPP) modes are excited at the two ports of a proposed splitter structure, and the two ports of the splitter structure are directly connected with two radiator structures, which are utilized to decouple the different frequency bands spoof SPP to free space wave by dispersion mismatching, achieving bidirectional and unidirectional radiation pattern in different frequency bands. From 8.4 to 21.6 GHz, this designed spoof SPP antenna possesses bidirectional endfire radiation pattern, and from 21.6 to 45.0 GHz, this designed spoof SPP antenna possesses unidirectional endfire radiation pattern. This designed spoof SPP antenna has an average gain over 10.6 dB in the whole working bandwidth, and the relative bandwidth of this antenna is 137%. Both the simulation and measurement results verify that the stable bidirectional and unidirectional radiation pattern of this proposed endfire spoof SPP antenna in wide bandwidth are achieved.

Ultrawideband Spoof Surface Plasmon Polariton Bidirectional Endfire Antenna Based on Wave Vectors Mismatching

In this work, an ultrawideband spoof surface plasmon polariton (SPP) bidirectional endfire antenna is proposed based on wave vectors’ mismatching. One splitter structure connects two radiator structures to form the proposed antenna, and two types of slot lines are used to design the splitter structure and the two radiator structures. Although the spoof SPP can transmit to the two radiator structures from the splitter structure, the wave vectors of the spoof SPP in the splitter structure and radiator structures are mismatched. Thus, the spoof SPP from the splitter structure will not be bounded mode when it propagates at the two radiator structures and will be decoupled by the two radiator structures, thereby realizing a bidirectional endfire radiation pattern. The bandwidth of the proposed antenna depends on the decoupling bandwidth of the spoof SPP based on wave vectors’ mismatching, which is determined by the working band of the splitter structure and the dispersion of radiator structures. This proposed antenna has a relative bandwidth of 120% from 9.6 to 40.00 GHz, average efficiency of 93%, and an average gain of over 9.2 dB, having great potential in microwave and millimeter communications.

Perovskite/InGaAs tandem cell exceeding 29% efficiency via optimizing spectral splitter based on RF sputtered ITO/Ag/ITO ultra-thin structure

In this paper, the optimization, elaboration and characterization of an efficient spectral beam splitter based on a simple RF sputtered ITO/Ag/ITO (IAI) ultra-thin multilayer structure are presented. An experimental investigation assisted by Genetic Algorithm (GA) metaheuristic optimization was carried out to achieve high-performance spectral splitter for tandem solar cell applications. The RF magnetron sputtering method was used to elaborate the optimized IAI structure. The optical and structural properties of the sputtered splitter were also analyzed using UV–Vis-IR spectroscopy and X-ray diffraction (XRD) measurements. It is found that the elaborated splitter structure offers 84% of transparency and a high reflectance of 87% with an optimum cut-off wavelength of 800 nm. This is attributed to the design approach, which leads to promote spectral splitting mechanism by inducing efficient optical modulation. Interestingly, a new Figure of Merit (FoM) parameter, which evaluates the optical splitting performances is proposed. Moreover, a new Perovskite/InGaAs tandem cell is proposed and analyzed to show the impact of the elaborated spectrum splitter on the solar cell efficiency. It is revealed that the investigated solar cell exhibits an improved efficiency approaching 30%. The latter value far surpasses that provided by Perovskite tandem cells. These results indicate that our spectrum splitting approach can open a new pathway towards designing high-performance tandem photovoltaic devices.

Intelligent design of large angle deflection beam splitter based on method of moving asymptotes

Photonic chip is a kind of integrated device that uses light as a carrier for information transportation and processing. Owing to its advantages of small size, lightweight, and low power consumption, photonic chip has become the most popular research topic nowadays. The beam splitter is a vital part of on-chip integration. For conventional beam splitting elements, Y-type and tree-branch output are the main elements, which are usually realized by interference principles. However, it is appropriate only for simple conventional beam splitter because the propagation direction of light cannot achieve large angle deflection. In the case of relay loading, optical amplification, pumping, and frequency upconversion, the vertical loading is often required without affecting the main optical path. To complete the large-angle deflection beam splitting, one needs to add a mirror to realize it or use a right-angle mirror structure for geometric double-sided reflection and splitting in traditional ways, but these structures are relatively complicated and difficult to complete on-chip integration. Based on previous work on inversely designed multi-channel wavelength routers and wide spectrum efficient focusing devices by using the intelligent algorithm, and combining the years of research on the coherent superposition theory of multi-scattering of the disordered medium, a large angle beam splitter that can realize from the near-infrared band is designed through using the intelligent algorithm. The beam splitter structure is based on AMTIR-1 glass, the part to be etched is air. The composition of AMTIR-1 is Ge<sub>33</sub>As<sub>12</sub>Se<sub>55</sub>. And the size of the structure is only 1 μm × 2 μm. The beam splitter can achieve 180° linear separation of beams in a range from 800 nm to 1100 nm, the beam splitting ratio of the entire waveband is approximately 1∶1, and the gross beam splitting efficiency is stable between 85% and 92%. Compared with several conventional structures with the same size, the efficiency of the beam splitter designed by this algorithm is higher. At the same time, the algorithm has the advantages of fast computation speed and small computation amount, and it can be completed only by ordinary personal computers without the support of hardware such as workstations. This intelligent algorithm can also be applied to the design of various passive photonic devices such as optical polarization splitters, routers, optical isolators, etc., providing an idea and reference for the design of integrated micro-nano photonic devices on high-density sheets.

Structural design of a novel fume hood for vapor and spatter removal in direct energy deposition via numerical investigation

Abstract This study demonstrates a novel design of a three-dimensional structural hood to remove the vapor and spatter generated during the Direct energy deposition (DED) process. The hood is composed of three planes, including an inlet block, an outlet block and a shell, with three splitter structures in each block. Computational fluid dynamics (CFD) simulation was implemented to match the inlet block with the outlet block, installing a horizontal splitter and a vertical splitter, respectively. With the proposed new designs, the gas flow state of vapor and spatter removal hood structures of different splitters is distinct. Through numerical simulation, one of the structures beneficial to vapor and spatter removal during DED process is proposed. The objects of different structural hoods were built by selective laser melting (SLM) additive manufacturing and the reliability of the simulation results is verified through experiments.

Numerical Investigation on Aerodynamic Performance of SCO2 and Air Radial-Inflow Turbines with Different Solidity Structures

Supercritical carbon dioxide (SCO2) is of great use in miniature power systems. It obtains the characteristics of high density and low viscosity, which makes it possible to build a compact structure for turbomachinery. For a turbine design, an important issue is to figure out the appropriate solidity of the rotor. The objective of this research is to present the aerodynamic performance and provide the design reference for SCO2 and air radial-inflow turbines considering different solidity structures. For the low solidity case of SCO2 turbine, new splitter structures are proposed to improve its performance. The automatic design and simulation process are established by batch modes in MATLAB. The numerical investigation is based on a 3D viscous compressible N-S equation and the actual fluid property of SCO2 and air. The distributions of flow parameters are first presented. Rotor blade load and aerodynamic force are then thoroughly analyzed and the aerodynamic performances of all cases are obtained. The SCO2 turbine has larger power capacity and higher efficiency while the performance of the air turbine is less affected by rotor solidity. For both SCO2 and air, small solidity can cause the unsatisfactory flow condition at the inlet and the shroud section of the rotor, while large solidity results in the aerodynamic loss at the trailing edge of rotor blade and the hub of rotor outlet. A suction side offset splitter can greatly improve the performance of the low solidity SCO2 turbine.

Numerical study and optimizing on cold plate splitter for lithium battery thermal management system

In recent years, with vigorous promotion of the new energy vehicle industry, electric vehicle, as an important direction, has aroused widely attention. As one of the core parts of electric vehicles, the performance of power battery is greatly affected by temperature. On the basis of the summaries of main methods and research of battery thermal management, this paper uses FloEFD 2016 to simulate and study the thermal equilibrium performance of battery liquid cooling system through adding splitters into the straight channel. In order to improve the thermal equilibrium of battery module, this paper also uses orthogonal experimental design method to research 5 splitter structure parameters: splitter number, length, angle, the distance between two splitters and the offset distance. The results show that as the number of splitters increases, the average temperature difference of each cell decreases and also the deflection angle and length of splitters have a great influence on the thermal equilibrium performance of the battery pack.

Polarization independent 1 × 3 equal optical power splitter based on self-collimation effect in two-dimensional photonic crystal

A polarization independent 1 × 3 equal optical power splitter (OPS) based on the self-collimation effect in two-dimensional (2-D) photonic crystal (PC) is proposed. Two splitter structures are introduced in the self-collimation 2-D PC, both of which have an air layer and a row of defect air holes. The proposed OPS is simulated using Rsoft software combined with plane wave expansion method and two finite-difference time-domain method. The results show that the beam for transverse electric (TE) mode and transverse magnetic (TM) mode can be self-collimated and divided equally into three outputs at the operating wavelength of 1310 nm. The transmission efficiencies are 95% for TE mode and 93% for TM mode, and the corresponding additional losses are 0.223 and 0.315 dB for TE mode and TM mode, respectively. The steady times are lower than 1.4 ps. The proposed polarization independent 1 × 3 equal OPS will have potential applications in optical fiber communication system.

On the dual core anisotropic metamaterial clad polarization splitter

A polarization splitter comprised of dual hollow-core anisotropic metamaterial (AMM) cladding was investigated. The proposed splitter structure inherits the properties of metal (Ag) and dielectric (Al2O3) mediums. The overall splitter performance was analyzed by evaluating the extinction ratio under different metal-dielectric concentrations in the AMM structure. For this purpose, the finite element method was used, and the splitting mechanism was analyzed by exploiting the coupled-mode theory. Also, the stability of splitter was tested under varying pitch values in the guide.

Temperature-programmed multicapillary gas chromatograph microcolumn for the analysis of odorous sulfur pollutants.

We report the fabrication and performance of a silicon-on-glass micro gas chromatography eight-capillary column based on microelectromechanical systems technology that is 50cm long, 30μm wide, and 300μm deep. According to the theory of a gas chromatography column, an even gas flow among different capillaries play a vital role in the peak broadening. Thus, a flow splitter structure is designed by the finite element method through the comparison of the velocity distributions of the eight-capillary columns with and without splitter as well as an open tubular column. The simulation results reveal that eight-capillary column with flow splitters can receive more uniform flow velocity in different capillaries, hence decreases the peak broadening and in turn increases the separation efficiency. The separation experiment results show that the separation efficiency of about 22000 plates/m is achieved with the chip column temperature programmed for analysis of odorous sulfur pollutants. This figure is nearly two times higher than that of the commercial capillary column coated the similar stationary phase. And the separation time of all the components in the microcolumn is less than 3.8min, which is faster than the commercial capillary column.

Terahertz Polarization Splitters Based on Total and Partial Coupling in Dual Slotted Core Polymer Fiber: Comparison and Analysis

Two terahertz (THz) polarization splitters based on dual slotted core polymer fiber are proposed and numerically investigated. The splitter structures are based on dual cores composed of subwavelength-scale air slots that are independently suspended within the fiber, which not only allows for single-mode propagation for the two orthogonal polarization modes with low absorption losses but enables them to couple with each other as well. Polarization splitters based on both symmetric and asymmetric dual slotted core structures, respectively, based on total and partial coupling are proposed and analyzed. The transmission modes, splitting lengths, and pertinent performance parameters of the two polarization splitters are investigated and numerically analyzed at a center-frequency of 1.0 THz. Comparisons of the two splitters with similar structural parameters are also carried out, which shows a comparably short splitting length of ∼1 cm and an ultra-low transmission loss of 0.4 dB with the asymmetric structure having a broader bandwidth and better extinction ratios.

Efficient Second Harmonic Generation in 3D Nonlinear Optical-Lattice-Like Cladding Waveguide Splitters by Femtosecond Laser Inscription.

Integrated photonic devices with beam splitting function are intriguing for a broad range of photonic applications. Through optical-lattice-like cladding waveguide structures fabricated by direct femtosecond laser writing, the light propagation can be engineered via the track-confined refractive index profiles, achieving tailored output beam distributions. In this work, we report on the fabrication of 3D laser-written optical-lattice-like structures in a nonlinear KTP crystal to implement 1 × 4 beam splitting. Second harmonic generation (SHG) of green light through these nonlinear waveguide beam splitter structures provides the capability for the compact visible laser emitting devices. With Type II phase matching of the fundamental wavelength (@ 1064 nm) to second harmonic waves (@ 532 nm), the frequency doubling has been achieved through this three-dimensional beam splitter. Under 1064-nm continuous-wave fundamental-wavelength pump beam, guided-wave SHG at 532 nm are measured with the maximum power of 0.65 mW and 0.48 mW for waveguide splitters (0.67 mW and 0.51 mW for corresponding straight channel waveguides), corresponding to a SH conversion efficiency of approximately ~14.3%/W and 13.9%/W (11.2%/W, 11.3%/W for corresponding straight channel waveguides), respectively. This work paves a way to fabricate compact integrated nonlinear photonic devices in a single chip with beam dividing functions.

Design and Analysis of Refractometer Based on Bend Waveguide Structure with Air Trench for Optical Sensor Applications

This study proposes a novel optical sensor structure based on a refractometer combining a bend waveguide with an air trench. The optical sensor is a 1 × 2 splitter structure with a reference channel and a sensing channel. The reference channel has a straight waveguide. The sensing channel consists of a U-bend waveguide connecting four C-bends, and a trench structure to partially expose the core layer. The U-bend waveguide consists of one C-bend with the maximum optical loss and three C-bends with minimum losses. A trench provides a quantitative measurement environment and is aligned with the sidewall of the C-bend having the maximum loss. The intensity of the output power depends on the change in the refractive index of the measured material. The insertion loss of the proposed optical sensor changes from 3.7 dB to 59.1 dB when the refractive index changes from 1.3852 to 1.4452.

A $1 \times N$ Lossless Adaptive Optical Power Splitter Employing an Opto-VLSI Processor

We propose and demonstrate the concept of a novel 1 × N lossless adaptive optical power splitter (OPS) structure integrating a software-driven Opto-VLSI processor, optical amplifiers, and an array of 4-f imaging systems. The active area of the Opto-VLSI processor is divided into M pixel blocks driven by multicasting phase holograms and aligned with an M-element lens array and a fiber array, thus forming an array of 4-f imaging systems. Each 4-f imaging system is capable of collimating and adaptively splitting an input optical beam emerging from an optical fiber and then coupling the split beams into different output fiber ports, thus realizing dynamic optical power splitting. The Opto-VLSI processor is driven by optimized multicasting phase holograms that adaptively split an incident laser beam along different angles; thus, user-defined splitting ratios can be achieved. Experimental results show that the optical amplifiers compensate for the splitting and the insertion losses, making the adaptive OPS lossless.