Single-polarization Single-mode Photonic Crystal Fiber Research Articles

Epsilon negative-based, broadband single-polarization single-mode hollow core anti-resonant photonic crystal fiber.

A broadband single-polarization single-mode (SPSM) hollow core anti-resonant photonic crystal fiber (HC-ARPCF) is proposed and analyzed by the finite element method in this paper. The HC-ARPCF design consisted of outer semicircular cladding tubes and inner circular cladding tubes. The SPSM behavior is achieved through controlling the effective material absorption loss (EML) by loading epsilon negative (ENG) material in the selected semicircular cladding tubes. Optimization of the configuration parameters is conducted to yield a large loss difference (LD) between one of the two orthogonally polarized fundamental modes and all the other unwanted modes. Therefore, only one desired mode will exist after a proper propagation distance, i.e., SPSM guidance. Specially, the optimal design provides a 288 nm (from 1408 nm to 1676 nm and from 1680 nm to 1700 nm) bandwidth in terms of 40 dB/m minimum LD (MLD) and 168 nm (from 1452 nm to 1620 nm) bandwidth in terms of 100 dB/m MLD. Furthermore, this fiber also exhibits a large effective mode area and near-zero dispersion properties over the entire operation bandwidth. The proposed HC-ARPCF may find its applications in polarization maintaining and high-power laser systems.

A Controllable Plasmonic Resonance in a SiC-Loaded Single-Polarization Single-Mode Photonic Crystal Fiber Enables Its Application as a Compact LWIR Environmental Sensor

Near-perfect resonant absorption is attained in a single-polarization single-mode photonic crystal fiber (SPSM PCF) within the long-wave infrared (LWIR) range from 10 to 11 m. The basic PCF design is a triangular lattice-based cladding of circular air holes and a core region augmented with rectangular slots. A particular set of air holes surrounding the core is partially filled with SiC, which exhibits epsilon near-zero (ENZ) and epsilon negative (ENG) properties within the wavelength range of interest. By tuning the configuration to have the fields of the unwanted fundamental and all higher order modes significantly overlap with the very lossy ENG rings, while the wanted fundamental propagating mode is concentrated in the core, the SPSM outcome is realized. Moreover, a strong plasmonic resonance is attained by adjusting the radii of the resulting cylindrical core-shell structures. The cause of the resonance is carefully investigated and confirmed. The resonance wavelength is shown to finely shift, depending on the relative permittivity of any material introduced into the PCF’s air holes, e.g., by flowing a liquid or gas in them. The potential of this plasmonic-based PCF structure as a very sensitive, short length LWIR spectrometer is demonstrated with an environmental monitoring application.

Design of single-polarization single-mode photonic crystal fiber filter with four small holes near the core based on second-order and third-order surface plasmon polariton modes

A single-mode single-polarization photonic crystal fiber (SMSP-PCF) filter at the wavelengths of 1.125 and 1.31 μm based on surface plasmon resonance is proposed and studied by the finite element method. Numerical results indicate that compared with the filter with the same size of holes near the core, the filter with four small holes near the core makes its extinction ratio (ER) at the wavelengths of 1.125 and 1.31 μm twice as large. That is, when the fiber length is 500 μm, the ER at 1.125 μm increases from 33.43 to 58.62 dB, and the ER at 1.31 μm increases from 129.41 to 244.85 dB. Furthermore, the designed SMSP-PCF filter also has a good structural tolerance. The proposed optical fiber filter has excellent performance of compact structure, high ER and good structural tolerance, and can be used in an integrated communication transmission system.

Design of a mid-infrared ultra-broadband chalcogenide Ge20Sb15Se65 -based single-polarization single-mode photonic crystal fiber with large nonlinearity

This paper proposes a mid-infrared (mid-IR) Ge20Sb15Se65-based photonic crystal fiber (PCF) with hexagonally latticed dual-rhombic air holes to deliver single-polarization single-mode (SPSM) over a broad waveband. The properties of SPSM bandwidth, confinement loss, birefringence, effective mode area and nonlinear coefficient are investigated in 2 μm–7 μm region by utilizing the finite difference time domain method (FDTD) together with anisotropic perfectly matched layer (PML). The results reveal that for the optimized geometric parameters of Λ = 2.6 μm, D = 2.4 μm, d = 1.2 μm, D1 = 2.2 μm, and d1 = 0.4 μm, the proposed PCF is a low-loss SPSM-PCF within the wavelengths ranging from 4.0338 μm to 7 μm, where only the x-polarization mode exists with the highest nonlinearity coefficient of 1468 w−1 km-1 (at 4.0338 μm). It will become an outstanding candidate for mid-IR optical fiber sensing/detection/ imaging/monitoring and nonlinear fiber optics.

Design of a Novel Mid-Infrared Single-Polarization Single-Mode Photonic Crystal Fiber with Low Loss, High Nonlinearity, and Large Bandwidth

ABSTRACTA novel mid-infrared Ge20Sb15Se65 chalcogenide-based single-polarization single-mode (SPSM) photonic crystal fiber (PCF) with rectangular latticed circular air holes is proposed. The properties of SPSM bandwidth, confinement loss, and nonlinearity are analyzed in the 3 μm~8 μm mid-infrared region using the finite -difference time-domain (FDTD) method. The influences of different geometrical parameters on the properties of SPSM-PCF are analyzed. All numerical computational results reveal that for the optimized geometrical parameters, the proposed PCF can deliver a SPSM region of more than 2.3814 μm with high nonlinearity of 3,705 w−1 km−1. Therefore, such a SPSM-PCF will become an excellent candidate for mid-infrared photonic.

A Double-Cladding Single Polarization Photonic Crystal Fiber and Its Structure Deviation Tolerance

We propose a novel broadband single-polarization single-mode (SPSM) photonic crystal fiber with hexagonally latticed circular airholes. Combined with our fabricated polarization maintaining fiber, it has demonstrated that the enlarged air holes in the outmost layer are superior for the confinement loss reduction. At the optimized parameters, the wavelength of SPSM region ranges from 1.52 to 2.13 $\mu$ m, where only y-polarized fundamental mode exists and the confinement loss is 0.051 dB/km at 1.55 $\mu$ m. The influence of realistic fabrication errors involving structure deviation on SPSM operation has also been systematically investigated.

Dispersion Engineering in Single-Polarization Single-Mode Photonic Crystal Fibers for a Nearly Zero Flattened Profile

We propose a systematic solution to the problem on dispersion engineering in single-polarization single-mode (SPSM) photonic crystal fibers (PCFs) for a nearly zero flattened profile. Based on dispersion-approximating and -normalizing methods as well as a clever engineering strategy, we have succeeded in a design of SPSM PCF with nearly zero flattened dispersion ${\text{0.82}}\pm {\text{0.30}}\,\text{ps}/\text{nm}/\text{km}$ over a broad band of ${\text{1.12}}\sim {\text{1.51}}\,\mu{\text{m}}$ . Moreover, such a fiber presents a very low confinement-loss level, which is less than 0.001 dB/km over the operation band.

A novel ultra-broadband single polarization single mode photonic crystal fiber

The concept of employing a central hole infiltrated with nematic liquid crystal (NLC) and two additional air holes in the core region is exploited to obtain an ultra-broadband single polarization single mode photonic crystal fiber (SPSM-PCF). The effects of structural parameters on the SPSM operation are studied using the full-vectorial finite element method. Numerical results show that the proposed structure can attain the SPSM operation bandwidth of 1610nm (from 1.51 to 3.12µm) with confinement loss lower than 0.01dB/km. The SPSM operation range can also be widely tuned to shorter wavelengths by adjusting the structure parameters. And meanwhile, a broad dispersion-flattened SPSM PCF is also obtained around the communication wavelength. Moreover, the dual-core SPSM PCF has also been investigated, enabling potential applications in the wavelength splitter of 1.31 and 1.55µm bands at a short fiber length of 1.629mm with SPSM operation.

Design of a Single-Polarization Single-Mode Photonic Crystal Fiber Filter Based on Surface Plasmon Resonance

We design a single-polarization single-mode photonic crystal fiber filter based on surface plasmon resonance. The finite element method is employed to evaluate the characteristics of the filter. The proposed fiber is devised such that there is a great discrepant confinement loss between two polarizations of x and y by varying two air holes in the cladding region, which is composed of hexagonal structural air holes in pure silica selectively filling with gold wires. Numerical simulations show that single-polarization single-mode operation waveband can be tuned by adjusting the parameters of the photonic crystal fiber. The confinement losses of the unwanted polarization can reach to 126.10 and 326.30 dB/cm in the wavelengths of 1.31 and 1.55 μm, while the corresponding confinement losses of the wanted polarized mode are only 0.08 and 1.20 dB/cm, respectively. Furthermore, the crosstalk can come to a maximum of 120.34 and 310.41 dB in the two communication bands. The bandwidths of the fiber designed for 1.31 and 1.55 μm are, respectively, 20 and 60 nm, which may be found useful applications for fiber polarizer.

Design of single-polarization single-mode coupler based on dual-core photonic crystal fiber

A single-polarization single-mode (SPSM) photonic crystal fiber (PCF) coupler is designed and inves- tigated by using full-vector finite-element method with the anisotropic perfectly matched layer. We numerically analyze the SPSM coupling properties with respect to the structure parameters and confinement loss character- istics. The results reveal that the coupling length between dual cores is as small as millimeter order of magnitude due to the wide silica bridge of energy transfer, and the SPSM coupling region can be tailored to cover the communication windows of 1.3 or 1.55 μm with optimized design parameters. Moreover, the confinement loss of x polarization is 3 orders of magnitude larger than that of y polarization in single polarization range. The proposed SPSM PCF coupler may find application in polarization-sensitive systems. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution

A design for single-polarization single-mode photonic crystal fiber with rectangular lattice

A design for single-polarization single-mode photonic crystal fiber with rectangular lattice is proposed in this paper. The proposed fiber is studied by the full vector finite element method with perfectly matched layers. The single-polarization single-mode operation region of the fiber is achieved in a certain wavelength range with low confinement loss include the wavelength of 1.55μm. The loss of one polarization is 0.124dB/km at the wavelength of 1.55μm and the confinement loss of the other one polarization is very high which can not ensure the transmission in the fiber. The single-polarization single-mode photonic crystal fiber is desirable for some polarization-sensitive applications such as high-power fiber lasers, fiber optic gyroscopes, current sensors and optical coherent communication systems.

Analysis of single polarization single mode photonic crystal cladding with hexagonal and rectangular lattice

Single-polarization single-mode (SPSM) operation of highly birefringent (HB) photonic crystal fibers (PCF) with rectangular and hexagonal lattice is investigated in detail by using a full-vector finite-element method (FEM) with anisotropic perfectly matched layers (PMLs). The position of the region of single polarization can be tuned freely by adjusting the size of the central enlarged air holes. The confinement loss and dispersion losses for standard single-mode fiber for particular SPSM PCFs are calculated and optimized. The proposed fibers are nonlinear SPSM, which may be useful for nonlinear optical applications or applications with a wide SPSM operating bandwidth requirement.

Broadband single-polarization single-mode photonic crystal fibers with three different background materials.

A modified structure of single-polarization single-mode (SPSM) photonic crystal fiber (PCF) with different background materials is presented and analyzed by using the full-vector finite-element method. Simulation results confirmed that the proposed PCF can realize low-loss SPSM on three wavebands with the same structure and different background materials. The wavebands are 1.46-1.60 μm for silica-based fiber, 1.97-2.3 μm for lead silicate glass fiber, and 3.16-3.58 μm for chalcogenide glass fiber. For three PCFs with different background materials, only the slow-axis mode exists and the confinement loss is less than 100 dB/m in the SPSM wavebands.

Ultra-broad band single-polarization single-mode photonic crystal fiber based on the zero-order surface plasmon polariton mode

An ultra-broad band single-polarization single-mode photonic crystal fiber (SPSM-PCF) is investigated based on zero order surface plasmon polariton mode by using the full vector finite element method (FEM). Highly wavelength-dependent transmission is obtained because of the band gap-liked effect of the bonding zero-order surface plasmon polariton mode stimulated over the interface of gold/liquid. With a filled RI of 1.52, the polarization extinction is higher than 30dB/cm among a large bandwidth of 360nm in the second communication window. The proposed SPSM-PCF also presents a large tolerance of the size deviation of gold-coated layer.

Design of ultrawideband single-polarization single-mode photonic crystal fiber with ultraflattened dispersion

An ultrawideband single-polarization single-mode (SPSM) and nearly zero flattened dispersion photonic crystal fiber (PCF) based on a rectangular lattice with square air holes is proposed. The performance of the PCF is investigated by using the full-vector finite element method, and the impact of variation of geometric parameters is also numerically analyzed. The simulation results reveal that the single-polarization bandwidth of the proposed PCF can achieve 1.4 μ m over 0.68 to 2.08 μ m for the optimized designed parameters and can be freely adjusted by tuning the air hole dimensions. The nearly zero flattened chromatic dispersion about 0 ± 0.8 ps /( km.nm ) can be obtained by controlling the size of the central hole, but its existence makes the power distribution extraordinary. Moreover, the confinement loss is less than 10 −6 dB/m over 0.68 to 1.86 μ m for the PCF with 10 rings of air holes. The proposed PCF may be useful for applications with a wide SPSM operating bandwidth or flattened dispersion requirement.

Design of wideband single-polarization single-mode photonic crystal fiber

A novel structure of single-polarization single-mode photonic crystal fiber (SPSM-PCF) is proposed by introducing two large semicircular holes on both sides of the core region. The characteristics of SPSM fibers are numerically analyzed using the finite-element method. The SPSM operating range can be adjusted with the parameters of the elliptical ratio γ and the spacing Λ 1 between the semicircular hole and the adjacent circular hole. The SPSM bandwidth of about 0.7 μm and operating range from 1.0 to 1.7 μm for the PCF have been obtained with the silica–air holes structure. An all-solid PCF structure is proposed, and the SPSM bandwidth of about 0.30 μm is predicted. With the increase in refractive index difference between the substrate and filling materials the SPSM operating range is blue-shifted, and with the decrease in the refractive index difference the bandwidth of the SPSM is reduced.

A novel single-polarization single-mode photonic crystal fiber with circular and elliptical air-holes arrays

A novel single-polarization single-mode photonic crystal fiber (SPSM-PCF) with circular and elliptical air-holes is proposed. The characteristics of the proposed SPSM-PCF are investigated by using a full-vector finite element method (FEM) with perfect matched layer (PML) boundary conditions. The results show that the SPSM operation is achieved with wider band, and the total dispersion profile of the SPSM-PCF is dispersion-flattened from 1.193 μm to 1.384 μm. This dispersion property makes the proposed SPSM-PCF useful for various applications, such as optical transmission and dispersion compensation for conventional fiber at long wavelength band with 500 nm negative dispersion region. It indicates that this is a good solution to realize broadband SPSM operation.

Single-polarization single-mode photonic crystal fibers with rectangular-lattice and elliptical-hole arranged perpendicular to each other

The present paper has proposed a novel photonic crystal fiber (PCF) structure for single-polarization single-mode (SPSM) operation. Applying the finite element method (FEM), the birefringence of cladding, with rectangular-lattice and elliptical-hole perpendicular to each other, have been studied for the first time. Employing this cladding structure, and with proper modification of inner cladding, PCFs with ultra wideband range of 830nm for SPSM operation are obtained.

A terahertz single-polarization single-mode photonic crystal fiber with a rectangular array of micro-holes in the core region

A single-polarization single-mode (SPSM) photonic crystal fiber with a rectangular array of micro-holes in the core region was designed in the terahertz frequency range near 1THz. Based on the asymmetric arrangement of the micro-holes, birefringence between the fundamental x-polarized and y-polarized modes is introduced. A SPSM operation of the terahertz fiber can be supported due to the different mode indices of the x-polarized and y-polarized modes. The SPSM operation band is about 320GHz with a central frequency of 1THz. In addition, the proposed terahertz fiber also shows a good property of reduced propagation loss comparing with the dielectric absorption.

Design of Broadband Single-Polarization Single-Mode Photonic Crystal Fiber Based on Index-Matching Coupling

A new type broadband single-polarization single-mode photonic crystal fiber based on index-matching coupling is proposed by using the full vector finite-element method. Polarization-dependent loss of the proposed fiber is larger than 24.08 dB/m within a wavelength range from 1.25 to 1.65 , and the single-polarization single-mode operation bandwidth reaches 400 nm.