Design of a photonic crystal fiber polarization beam splitter with simple structure and ultra-wide bandwidth

A novel polarization beam splitter(PBS)based on dual-core photonic crystal fiber(DC-PCF)is proposed in this work.The proposed DC-PCF PBS contains two kinds of lattices and three kinds of air holes to form the asymmetrical elliptic dual-core structure.By using the full-vector finite element method,the propagation characteristics of the proposed DC-PCF PBS are investigated.The simulation results show that the bandwidth of the proposed DC-PCF PBS can reach to 340 nm,which covers the S+C+L+U communication bands,the shortest splitting length is 1.97 mm,and the maximum extinction ratio appears near wavelength 1550 nm.Moreover,the insertion loss of the proposed DC-PCF PBS is very low.It is believed that the proposed DC-PCF PBS has important applications in the field of all-optical communication and network.

Ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber

An ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber （GDC-PCF） that can work in a wavelength range from 1120 nm to 1730 nm is proposed in this paper. Through optimizing fiber configuration, the polarization splitter has an extinction ratio of-56.3 dB at 1.55 μm with a fiber length of 4.8 mm. Compared with the photonic crystal fiber reported splitters, to our knowledge, the GDC-PCF splitter with the extinction ratio below-20 dB has a super wide bandwidth of 610 nm. Due to the excellent splitting characteristics, the GDC-PCF will be used in coherent optical communication systems in a wavelength range from infrared to mid-infraed.

Design of a polarization splitter for an ultra-broadband dual-core photonic crystal fiber

A novel ultra-broadband polarization splitter based on a dual-core photonic crystal fiber(DC-PCF)is designed.The full-vector finite element method and coupled-mode theory are employed to investigate the characteristics of the polarization splitter.According to the numerical results,a graphene-filled layer not only broadens the working bandwidth but also reduces the size of the polarization splitter.Furthermore,the fluorine-doped region and the germanium-doped region can broaden the bandwidth.Also,the 4.78 mm long polarization splitter can achieve an extinction ratio of-98.6 d B at a wavelength of 1550 nm.When extinction ratio is less than-20 d B,the range of the wavelength is 1027 nm-1723 nm with a bandwidth of 696 nm.Overall,the polarization splitter can be applied to all-optical network communication systems in the infrared and near-infrared wavelength range.

Designing of a polarization beam splitter for the wavelength of 1310 nm on dual-core photonic crystal fiber with high birefringence and double-zero dispersion

We have proposed a novel kind of photonic crystal fiber which contains two asymmetric cores. The bireti＇ingence and the dispersion are numerically analyzed based on finite element method when the size of the air holes and the pitch of two adjacent air holes are changed. It is shown that the proposed photonic crystal fiber has high birefringence up to the order of 10-2 and double-zero dispersion points are at the wavelengths of 1310 nm and 800 rim, simultaneously. At the same time, the normalized power and the extinction ratios of the proposed photonic crystal fiber have been simulated. It is demonstrated that, at the wavelength of 1310 rim, the x-polarized mode and the y-polarized mode are separated when the propagation distance is 2.481 ram.

Ultra-thin two-dimensional transmissive anisotropic metasurfaces for polarization filter and beam steering application

We propose an anisotropic planar transmitting metasurface, which has the ability to manipulate orthogonally-polarized electromagnetic waves in the reflection and refraction modes respectively. The metasurface is composed of four layered rectangular patches spaced by three layered dielectric isolators each with a thickness of 0.15λ0 at 15 GHz. By tailoring the sizes of the patches, the metasurface functions as a band-stop filter for the y-polarzied wave and a band-pass filter for the x-polarized wave operating from 14 GHz to 16 GHz. Moreover the phases of the transmitting x-polarized wave can be modulated at about 15 GHz, which contributes to beam steering according to the general refraction law. Experimental results are in good accordance with the simulated ones, in which the reflection efficiency is almost 100% while the transmission efficiency of the x-polarized wave reaches 80% at 15 GHz. Besides, the transmitted x-polarized wave is effectively manipulated from 14 GHz to 16 GHz.

Theoretical simulation of a polarization splitter based on dual-core soft glass PCF with micron-scale gold wire

A polarization splitter based on dual-core soft glass photonic crystal fiber （PCF） filled with micron-scale gold wire is proposed. The characteristics of the polarization splitter are studied by changing the structural parameters of the PCF and the diameter of the gold wire with the finite element method （FEM）. The simulation results reveal that the coupling length ratio of the soft glass-based PCF is close to 2 and the corresponding curve is more fiat than that of the silica-based PCE The broadband bandwidth is 226 nm in which the extinction ratio is lower than -20 dB by the soft glass-based PCE i.e., from 1465 nm to 1691 nm which is competitive in the reported polarization splitters, and the bandwidth is just 32 nm by the silica-based PCE The insertion loss by our polarization splitter is just 0.00248 dB and 0.43 dB at the wavelength of 1.47 μm and 1.55 μm. The birefringence is obviously increased and the coupling length is decreased by filling gold wire into the soft glass-based or the silica-based PCE Also the birefringence based on the silica-based PCF is much larger than that based on the soft glass-based PCF whether or not the gold wire is introduced. The fabrication tolerance of the polarization splitter is also considered by changing the structural parameters. The polarization splitter possesses broad bandwidth, low insertion loss, simple structure and high fabrication tolerance.

Designing analysis of the polarization beam splitter in two communication bands based on a gold-filled dual-core photonic crystal fiber

We design a novel kind of polarization beam splitter based on a gold-filled dual-core photonic crystal fiber （DC-PCF）. Owing to filling with two gold wires in this DC-PCF, its coupling characteristics can be changed greatly by the second-order surface plasmon polariton （SPP） and the resonant coupling between the surface plasmon modes and the fiber-core guided modes can enhance the directional power transfer in the two fiber-cores. Numerical results by using the finite element method show the extinction ratio at the wavethlengths of 1.327 μm and 1.55 μm can reach -58 dB and -60 dB and the bandwidths as the extinction ratio better than -12 dB are about 54 nm and 47 nm, respectively. Compared with the gold-unfilled DC-PCF, a 1.746-mm-long gold-filled DC-PCF is better applied to the polarization beam splitter in the two communication bands of λ = 1.327 μm and 1.55 μm.

Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler

In this paper a compact polarization beam splitter based on a deformed photonic crystal directional coupler is designed and simulated. The transverse-electric （TE） guided mode and transverse-magnetic （TM） guided mode are split due to different guiding mechanisms. The effect of the shape deformation of the air holes on the coupler is studied. It discovered that the coupling strength of the coupled waveguldes is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.Sttm. A finite-difference tlme-domain simulation is performed to evaluate the performance of the device, and the extinction ratios for both TE and TM polarized light are higher than 20 dB.

Ultra-thin anisotropic transmitting metasurface for polarization beam splitter application

We report a polarization beam splitter based on phase gradient metasurface for microwave frequency region.The metasurface is constructed by anisotropic cells with independent phase response for differently-polarized waves.Through putting different gradient phases for orthogonally-polarized waves on a focusing metasurface,the anisotropic sample has the ability to enhance gain and split orthogonally-polarized waves.The simulation results indicate that the incident spherical waves are converted into plane waves and split into an x-polarized wave with a refraction angle of-24° and a ypolarized wave with a refraction angle of 37.6° in the y direction.For verification,a metasurface sample with a size of 102.5 mm x 102.5 mm is fabricated and measured.The consistence between numerical and experimental results validates the improved gain of 10.5-dB against the feed source and the splitting effect.Moreover,the thickness of the proposed metasurface is 3 mm which is ultra-thin against the wavelength at 15 GHz.The proposed prescription opens a new route to the applications of anisotropic metasurface in microwave band.

Terahertz Wave Polarization Beam Splitter Using Asymmetrical Coupler

This study has proposed and numerically demonstrated a compact terahertz wave polarization beam splitter. The splitter is built by using a asymmetrical directional coupler consisting of a bend waveguide and a slot bend waveguides and achieves a high extinction ratio of 24.88 dB and 16.55 dB for cross and through ports. The optimal coupling region length is found to be 26 ttm. By using such a polarization beam splitter, the size of the terahertz wave system could he reduced significantly. The simulation results show that the designed polarization beam splitter can split TE- and TM-polarized terahertz wave into different propagation directions with high efficiency over the terahertz wave frequency range from 9.40 THz to 9.65 THz. The device obtained is readily used for a polarization diversity terahertz wave integrated circuit field, particularly for platforms with slot waveguide.

An Ultra-Compact Broadband Polarizing Beam Splitter Utilizing Hybrid Plasmonic Waveguide

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.

Performance measurement of broadband, wide-angle polarizing beam splitter

Polarizing beam splitter (PBS) is a critical optical component in projection display system because PBS performance greatly influences the contrast and brightness of the system. PBS performance is usually measured by spectrophotometer after coating and cementing, but the measured result cannot represent the actual performance in practice because people usually change the incident angle in one plane (horizontal plane) and do not consider the other plane (vertical plane). Geometrical polarization rotation occurring at reduced F-number influences the measuring precision of s-polarization transmittance (Ts) and p-polarization reflectance (Rp). A more accurate and practical way to measure the performance of broadband, wide-angle PBS is presented in this paper.

Optimal design of sub-wavelength metal rectangular gratings for polarizing beam splitter based on effective medium theory

A novel optimal design of sub-wavelength metal rectangular gratings for the polarizing beam splitter （PBS） is proposed. The method is based on effective medium theory and the method of designing single layer antireflection coating. The polarization performance of PBS is discussed by rigorous couple-wave analysis （RCWA） method at a wavelength of 1550 nm. The result shows that sub-wavelength metal rectangular grating is characterized by a high reflectivity, like metal films for TE polarization, and high transmissivity, like dielectric films for TM polarization. The optimal design accords well with the results simulated by RCWA method.

Scheme for Realizing Probabilistic Teleportation of Bipartite Photonic States via Linear Optical Elements

We propose a probabilistic scheme for realizing teleportation of bipartite photonic states using linear optical elements where only requires a two-photon Bell state used as quantum channel. It reduces the requirement of the entanglement of quantum channel, but requires an additional photon and an auxiliary maximally entangled photon pair locally.

Monochrome HUD’s Imaging Projector Based on Laser-DMD System

Design and tolerance of a new head up display’s projector system is reported. It is based on laser-micro display modules. We designed optical diffraction limited modules and some of our novelties were compactness, using common material and spherical lenses in optical design, easy and economical manufacturing process, uniform intensity and minimum aberrations of final image, economical and repairable designed system. Projector magnification is 10.0X and diagonal of image plane is 76.2 mm. ZEMAX software is employed for optical design and tolerance.

Design of a C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler

A C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed. The mode-evolution structure is designed in a bi-level taper through which the TM;mode can evolve into the TE;mode. Then the TE;mode is coupled to the TE;mode at the cross port using the asymmetric directional coupler. The input TE;mode propagates along the waveguide without mode conversion and output at the through port. From the experimental results, the extinction ratio is lower than 30 dB and the excess loss is less than 1 dB for input TE;mode at the whole C-band. For input TM;mode, the ER and the EL are, respectively,lower than-10 and 1.5 dB.

High-performance ultra-compact polarization splitterrotators based on dual-etching and tapered asymmetrical directional coupler

High-performance ultra-compact polarization splitter-rotators(PSRs)are designed and experimentally demonstrated,using dual etching and a tapered asymmetrical directional coupler.First,two novel PSRs are designed with nanowire and subwavelength grating cross-port waveguides and verified in simulations.Then,one of the two PSRs is fabricated.Experiment results reveal that the extinction ratio is higher than 28 dB or 32 dB at 1550 nm for the launched fundamental transverse magnetic or the transverse electric modes,while the corresponding insertion loss and polarization conversion loss are 0.33 dB and 0.18 dB,respectively.

On-chip silicon polarization and mode handling devices

Mode-and polarization-division multiplexing are new promising options to increase the transmission capacity of optical communications.On-chip silicon polarization and mode handling devices are key components in integrated mode-and polarization-division multi-plexed photonic circuits.In this paper,we review our recent progresses on silicon-based polarization beam splitters,polarization splitters and rotators,mode（de）multiplexers,and mode and polarization selective switches.Silicon polarization beam splitters and rotators are demonstrated with high extinction ratio,compact footprint and high fabrication tolerance.For on-chip mode multiplexing,we introduce a low loss and fabrication tolerant three-mode（de）multiplexer employing sub-wavelength grating structure.In analogy to a conventional wavelength selective switch in wavelength-division multi-plexing,we demonstrate a selective switch that can route mode-and polarization-multiplexed signals.

Asymmetric directional couplers based on silicon nanophotonic waveguides and applications

Directional couplers （DCs） have been playing an important role as a basic element for realizing power exchange. Previously most work was focused on symmetric DCs and little work was reported for asymmetric directional couplers （ADCs）. In recently years, silicon nanophotonie waveguides with ultra-high index contrast and ultra-small cross section have been developed very well and it has been shown that ADCs based on silicon-oninsulator （SOI） nanophotonic waveguides have some unique ability for polarization-selective coupling as well as mode-selective coupling, which are respectively very important for polarization-related systems and mode-division-mulitplexing systems. In this paper, a review is given for the recent progresses on silicon-based ADCs and the applications for power splitting, polarization beam splitting, as well as mode conversion/（de）multiplexing.

Design and fabrication of an embedded wire-grid nanograting

An embedded wire-grid nanograting was designed and fabricated for using as a broadband polarizing beam splitter to reflect s-polarized light and transmit p-polarized light. A protected cladding layer of the same material as the grating＇s was deposited on the ridge, whereas the wire-grid is deposited in the grating trenches, which makes it more firm during application. High polarization extinction ratios of above 40 and 20 dB for transmission and reflection, respectively, with a broad wavelength range for the whole optical communication bandwidth （850 -1700 nm） and a wide angular tolerance （〉 ±20 °） are obtained by optimization of the designed structures, and the grating period is 200 nm.