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In this paper, unlike many researches that focus on beam splitters based on gratings with symmetrical structures, an asymmetric grating with double-groove structure is proposed. Based on the double-groove grating, multi-port beam splitters including dual-port, three-port, and four-port, under normal incidence working at terahertz frequency are designed for both transverse-electric and transverse-magnetic polarizations. Rigorous couple-wave analysis and simulated annealing algorithm are employed to get the optimal parameters of the grating and accelerate the computing process. For the purpose of understanding the phenomenon of the beam incident, the finite element method is also applied to get the simulation result. It is proven that the proposed beam splitters all present great efficiency and uniformity on the energy distribution. High manufacturing tolerance of the beam splitters is also analyzed, which allows for greater flexibility in the fabrication process. Compared with beam splitters based on single-groove grating, multi-port beam splitters based on double grooves show great performance and universality. [ABSTRACT FROM AUTHOR]

With zeroth-order suppression, a double-groove reflective grating for dual-port reflection beam splitter is studied in this paper. Under normal incidence, the grating obtains great efficiencies for both TE and TM polarizations. The parameters of the double-groove grating are derived using rigorous coupled-wave analysis. The finite element method and the simulated annealing algorithm are also presented to make sure that the ideal parameters are obtained. Total efficiencies of 98.95% for TE polarization and 99.30% for TM polarization are realized at an incidence wavelength of 1550 nm. In the meantime, the efficiencies of TE polarization and TM polarization at ± 1st orders are 48.15% and 46.26%, while at zeroth order, they are being effectively suppressed at 2.41% and 6.56%. The suggested grating has exceptional qualities and performs admirably. [ABSTRACT FROM AUTHOR]

In this paper, a controllable hybrid plasmonic integrated circuit (CHPIC) composed of hybrid plasmonic waveguide (HPW)-based rhombic nano-antenna, polarization beam splitter, coupler, filter, and sensor has been designed and investigated for the first time. In order to control the power into a corresponding input port, a graphene-based 1 × 3 power splitter with switchable output has been exploited. The functionality of each device has been studied comprehensively based on the finite element method and the advantages over state-of-the-art have been compared. Moreover, the effect of connection of CHPIC to the photonic and plasmonic waveguides has been studied to exhibit the capability of variety excitation methods of the CHPIC. Furthermore, the performance of the proposed CHPIC connected to inter/intra wireless transmission links has been investigated. The wireless transmission link consists of two HPW-based nano-antennas as transmitter and receiver with the maximum gain and directivity of 10 dB and 10.2 dBi, respectively, at 193.5 THz. The suggested CHPIC can be used for applications such as optical wireless communication and inter/intra-chip optical interconnects. [ABSTRACT FROM AUTHOR]

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 1 × 2 and 1 × 4 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 1 × 2 , 1 × 4 Y-shaped beam splitters show that our optimization technique is efficient and simple. And the total transmission efficiencies both over 7 2 % at output ports are obtained, which indicates that our method is relatively efficient to other methods in some related reports. [ABSTRACT FROM AUTHOR]

In this paper, a reflective trapezoidal dual-functional beam splitter grating is proposed, which performs two independent functions at 1550 nm. For TE polarization, the grating can achieve a uniform three-port output with efficiencies of 32.85%, 32.89%, and 32.75% for 0th, -1st, and -2nd orders respectively. For TM polarization, the grating can achieve a highly-efficient single-channel output of order -2nd with an efficiency of 93.27%. HfO 2 is chosen as the material of grating ridge layer, the structural parameters of the grating are studied by using rigorous coupled-wave analysis (RCWA) and simulated annealing algorithm (SAA), and the results are verified by using finite element method (FEM). In addition, the influence of structure and incident error on grating efficiency was also analyzed, the results indicate that the grating has good incident bandwidth and manufacturing tolerance with excellent performance. • Trapezoidal dual-functional splitter with two reflective independent functions. • For TE polarization, a uniform three-port with efficiencies of 32.85%, 32.89%, and 32.75% for 0th, -1st, and -2nd orders. • For TM polarization, a highly-efficient single-channel output of order -2nd with an efficiency of 93.27%. [ABSTRACT FROM AUTHOR]

Four-port beam splitter with good uniformity was proposed by T-type double-layer with different dielectric grating. The total efficiency of the beam splitter is over 90% with beam splitting uniformity better than 3%. At the same time, the simplified modal analysis is added to calculate the grating mode and effective refractive index of the grating area, which clearly describes the physical propagation mechanism inside the grating. The finite element method is used to investigate the normalized field of the grating, which more intuitively reflects the way of energy transfer inside the grating. Finally, the incident characteristics and manufacturing tolerance of the grating are analyzed. Properties of the T-type grating were analyzed in three methods, which more fully illustrates the applicability and stability of the grating in this paper. [ABSTRACT FROM AUTHOR]

• The length of the designed PBS based on DNDHC-NCF is 1.38 cm, which solves the technical problems of long length of traditional PBS. • The operation bandwidth is 320 nm, covering S + C + L + U bands. • Is of great significance in promoting the application and development of DNDHC-NCF. In this paper, a polarization beam splitter（PBS） based on double nested dual-core negative-curvature fiber (DNHC-NCF) is designed. Two hollow cores are constructed by eight double nested cladding tubes arranged at certain angles. The influences of structural parameters on the performances of the DNHC-NCF PBS have been studied by using the finite element method (FEM). According to the simulation results, the structure of the proposed DNHC-NCF PBS is optimized. The final results indicate that the length of the proposed DNHC-NCF PBS is 1.38 cm and the extinction ratio (ER) is less than −20 dB in the wavelength range of 1.48–1.80 µm (320 nm, covers S + C + L + U bands). Besides, the higher order mode extinction ratio (HOMER) in the wavelength range of 1.3–1.71 µm is greater than 100, showing good single-mode characteristic as well. It is believed that the proposed double nested dual-core negative curvature fiber polarization beam splitter will have important applications in the fields of optical communication system. [ABSTRACT FROM AUTHOR]

In this paper, a polarization beam splitter (PBS) based on the gold wire-filled dual-core photonic crystal fiber is proposed. The full-vector finite element method is used to investigate the influences of the fiber structure parameters on the transmission characteristics and coupling length. By appropriately adjusting the fiber structure parameters, the coupling length ratio of 2:1 can be achieved at wavelengths 1.55 and 1.31 μm, so the incident light can be well separated into the two beams with orthogonal polarization states. When the fiber length is 805.3 μm, the maximum extinction ratio (ER) within bandwidth of 60 nm is −132.12 dB at wavelength 1.55 μm. When the fiber length is 1264.9 μm, the maximum ER within bandwidth of 70 nm is −197 dB at wavelength 1.31 μm. By optimizing the fiber structure parameters, a PBS with a length of 249.12 μm, the maximum ER of −112.2 dB, and bandwidth of 120 nm can be obtained. [ABSTRACT FROM AUTHOR]

A new three-channel beam splitter with dual-structure is described in this paper. Through numerical calculation by finite element method (FEM), with an incident wavelength of 1550 nm, such the dual-structure grating can be obtained with diffraction efficiencies of more than 32% in the ± 1st and 0th order for transverse magnetic (TM) polarization and more than 31% for transverse electric (TE) polarization. The effect of period, duty cycle, incident angle and wavelength on the diffraction efficiency are also presented in this paper. Compared with other three-channel gratings, the proposed grating has wider incident wavelength bandwidth and satisfying performance. [ABSTRACT FROM AUTHOR]

An ultra-bandwidth and single-mode polarization beam splitter (PBS) of dual hollow-core anti-resonant fiber (DHC-ARF) with circular outer tubes and inner tubes is proposed. Four outer tubes are introduced in the horizontal direction to obtain two hollow cores. The modal coupling is realized through the gap between the two hollow cores. The inner tubes also are inserted into two the outer tubes between the two hollow cores for realizing ultrawide bandwidth in DHC-ARF. To achieve single-mode performance, the high-order modes are coupled with the cladding modes by optimizing the diameter of outer tubes and the inner tubes. The calculation results show that an 11.0 cm long DHC-ARF can be used to develop a PBS with an operating bandwidth of 410 nm, where the polarization extinction ratio is lower than −20 dB. The high-order mode extinction ratio is 625.41, and the loss of fundamental mode is below 1.018 dB/m. • Because the size of elliptical tubes is hard to fabricate, an ultra-bandwidth and single-mode PBS of DHC-ARF completely composed of circular cladding tubes and nested tubes is proposed in the structures. • The influence factors related to bandwidth, the high-order mode extinction ratio and coupling length of PBS based on DHC-ARF are systematically studied by a full-vector finite element method. • The propagation process of light in the optical fiber is also simulated by the light speed propagation method. When the light travels to a certain distance, the two polarized lights will be separated. • Numerical simulation shows an 11.0 cm long DHC-ARF can be used to develop a PBS with an operating bandwidth of 410 nm ranging from 1.35 to 1. 76 μ m , where the polarization extinction ratio reaches −39.0 dB, the high-order mode extinction ratio is 625.41. • The PBS based on DHC-ARF with circular cladding tubes and nested tubes proposed in this paper compares the performance with other existing PBS, this PBS has the widest bandwidth. [ABSTRACT FROM AUTHOR]

• The nano-grating has the multi-port beam control for four- or five-port output in a 2D plane by with nanodisk arrays. • For four-port output, (0, ±1) and (±1, 0) orders are 24.11% and 23.72% with a PDL of 0.08 dB. • For five-port output, (0, 0), (0, ±1) and (±1, 0) orders are 19.29%, 19.45% and 19.36% with a PDL of 0.06 dB. In this article, a multi-port two-dimensional (2D) reflective grating by a nanodisk array is proposed, which can be used for high-efficiency four-port ((0, ±1) and (±1, 0) orders) and five-port ((0, 0), (0, ±1) and (±1, 0) orders) optical control at a communication wavelength. Finite element method provides fast and effective optimization and analysis of the proposed 2D grating, while the 3D finite-difference time-domain provides strong support for the data in this paper. The four-port grating beam splitter has an efficiency of nearly 24% for all main diffraction orders with uniformity and polarization-dependent losses (PDL) of 0.8% and 0.08 dB, respectively. Meanwhile, the five-port grating beam splitter achieves an efficiency of over 19% for each diffraction order and in excess of 96% overall, with a uniformity and PDL of 0.4% and 0.06 dB, respectively. In addition, the detailed analysis of bandwidth performance and manufacturing tolerances shows the advantages of the proposed 2D nano-grating in practical applications and manufacturing. These findings have positive implications for future research on 2D nano-gratings, and the proposed 2D nano-grating has promising applications in the fields of sensor networks, grating measurements, photonic crystals, etc. [ABSTRACT FROM AUTHOR]

An enhanced newly high-efficiency dual-function beam splitter of the grating is described in this paper. The proposed grating can realize newly dual-function at infrared wavelength under second Bragg incidence, which can function as high-efficiency component for TE polarization. Moreover, under TM polarization, the grating is different from the other traditional dual-function grating, which can achieve a three-port output with high efficiency and good uniformity. By using the finite element method, an optimum grating structure can be presented with the efficiency of three diffraction orders (0th, −1st, −2nd) for TM polarization greater than 30%. As for TE polarization, the efficiency of −2nd order will be better than 95% with a wide bandwidth. Therefore, the proposed grating can be well applied in variety optical fields. [ABSTRACT FROM AUTHOR]

A polarization beam splitter is an important component of modern optical system, especially a splitter that combines the structural flexibility of photonic crystal fiber and the optical modulation of functional material. Thus, this paper presents a compact dual-core photonic crystal fiber polarization beam splitter based on thin layer As2S3. The mature finite element method was utilized to simulate the performance of the proposed splitter. Numerical simulation results indicated that at 1.55 μm, when the fiber device length was 1.0 mm, the x- and y-polarized lights could be split out, the extinction ratio could reach −83.6 dB, of which the bandwidth for extinction ratio better than −20 dB was 280 nm. It also had a low insertion loss of 0.18 dB for the x-polarized light. In addition, it can be completely fabricated using existing processes. The proposed compact polarization beam splitter is a promising candidate that can be used in various optical fields. [ABSTRACT FROM AUTHOR]