NONLINEAR PROPERTIES OF STRUCTURAL HETEROGENEOUS PHOTONIC CRYSTAL FIBERS WITH As2Se3 SUBSTRATE

We examine the possibility of improving the nonlinear properties of photonic crystal fibers (PCFs) with As2Se3 substrates by creating a difference in the diameters of the air holes of the rings around the core. With the new design, all-normal dispersion properties, small effective mode area, high nonlinear coefficient, and low confinement loss were achieved in the long-wavelength range of 2.0–7.0 µm. The highest nonlinear coefficient is 4414.918 W-1.km-1 at 4.5 µm for the lattice constant (Ʌ) of 3.0 µm and the filling factor (d/Ʌ) of 0.85, while the lowest loss is 1.823´10-21 dB/cm with Ʌ = 3.5 µm and d/Ʌ = 0.8. Based on the numerical simulation results, the characteristics of two optimal structures have been analyzed in detail to guide the application in supercontinuum generation.

Efficient Photonic Crystal Fiber Design for Higher OAM Modes with Low Loss Towards Next Generation THz Communication

A newer and efficient solid core with air holes and ring based circular photonic crystal fiber (C-PCF) design is proposed, developed, and studied. The C-PCF structure with a ring core and three layers of air holes is developed to communicate terahertz frequency of the range of 1 THz to 3 THz. Finite element method (FEM) is used to optimize the position, shape and dimensions of air holes and refractive index (RI) of material for the proposed PCF design and check the efficiency to support different orbital angular momentum (OAM) modes for communication. Our novel designed C-PCF supports multiple stable modes with mode purity above 0.9. Confinement loss is in the range of 10-12 dB/cm, highest effective mode area in the order of 1 mm2 is achieved in the investigated study for 3 THz transmission. The study observes that the performance of PCF is strongly dependent on RI of core and cladding.

Terahertz Sensor via Ultralow-Loss Dispersion-Flattened Polymer Optical Fiber: Design and Analysis

A novel cyclic olefin copolymer (COC)-based polymer optical fiber (POF) with a rectangular porous core is designed for terahertz (THz) sensing by the finite element method. The numerical simulations showed an ultrahigh relative sensitivity of 89.73% of the x-polarization mode at a frequency of 1.2 THz and under optimum design conditions. In addition to this, they showed an ultralow confinement loss of 2.18 × 10−12 cm−1, a high birefringence of 1.91 × 10−3, a numerical aperture of 0.33, and an effective mode area of 1.65 × 105 μm2 was obtained for optimum design conditions. Moreover, the range dispersion variation was within 0.7 ± 0.41 ps/THz/cm, with the frequency range of 1.0–1.4 THz. Compared with the traditional sensor, the late-model sensor will have application value in THz sensing and communication.

Design and Analysis of Heptagonal Cladding With Rotated-Hexa Elliptical Core Based PCF for the Applications of Communication Sectors in the THz Region

Photonic crystal fiber (PCF) beside heptagonal cladding with elliptical rotated-hexa curved center are talked about for terahertz (THz) waveguide. It is recognized that a successful effective material loss (EML) of 0.0076 cm-1 has been accomplished at 1 THz working recurrence. By utilizing the photonic crystal fiber PCF) concept, all reenactment comes about have been gotten with the limited finite element method (FEM) and perfectly match layer (PML) border conditions based on COMSOL Multiphysics computer apparatuses. This PCF fiber uncovers EML of 0.0076 cm−1, with expansive an effective area (EA) of 5.95×10-8 m2 and stream of control within the center locale of 90% at 1 THz. Besides, around pivotal optical directing viewpoints like as restriction misfortune, scattering, methodology, power fraction (PF) and effective mode area (EMA) have been too considered briefly. It is expected that the mentioned PCF waveguide will offer a significant improvement over existing design for communication field. Maintaining the typical principles for all the optical constraints suggests that the anticipated PCF can proficiently be pragmatic in multichannel communication and some other domains of the THz technology.

Amplification characteristics in active tapered segmented cladding fiber with large mode area

A kind of tapered segmented cladding fiber (T-SCF) with large mode area (LMA) is proposed, and the mode and amplification characteristics of T-SCFs with concave, linear, and convex tapered structures are investigated based on finite-element method (FEM) and few-mode steady-state rate equation. Simulation results indicate that the concave tapered structure can introduce high loss for high-order modes (HOMs) that is advantageous to achieve single-mode operation, whereas the convex tapered structure provides large effective mode area that can help to mitigate nonlinear effects. Meanwhile, the small-to-large amplification scheme shows further advantages on stripping off HOMs, and the large-to-small amplification scheme decreases the heat load density induced by the high-power pump. Moreover, single-mode propagation performance, effective mode area, and heat load density of the T-SCF are superior to those of tapered step index fiber (T-SIF). These theoretical model and numerical results can provide instructive suggestions for designing high-power fiber lasers and amplifiers.

SIMULATION STUDY ON SUPERCONTINUUM GENERATION AT NORMAL DISPERSION REGIME OF A CARBON DISULFDE-CORE PHOTONIC CRYSTAL FIBER

A photonic crystal fiber with a hollow core filled with carbon disulfide (CS2) is proposed as a new source of supercontinuum light. We numerically study guiding properties of modeled fibers including the dispersion and the effective mode area of the fundamental mode. As a result, octave spanning of the SC spectrum was achieved in the wavelength range of near-IR from 1.25 μm to 2.3 μm with 90 fs pulse and energy of 1.5 nJ at a pump wavelength of 1.55 μm. The proposed fibers are fully compatible with all-silica fiber systems, in particular, could be used for all-fiber SC sources and new low-cost all-fiber optical systems.

Highly negative dispersion compensating fiber with low third order dispersion

In this work, a dispersion compensating photonic crystal fiber (DC-PCF) is proposed in which dispersion, dispersion slope, second order dispersion, third order dispersion, nonlinearity, effective mode area, V parameter are investigated. The suggested structure is very effective for compensating of chromatic dispersion about −951 to −3075.10 ps/(nm.km) over 1340–1640 nm wavelength bandwidth. With perfectly matched layer boundary condition, guiding properties are inspected applying finite element method (FEM). The investigated results conform the opportunity of large negative dispersion and high group velocity dispersion (GVD) of −2367.10 ps/(nm.km) and 3018.55 ps2/km respectively, at 1550 nm operating wavelength. The offered fiber also shows low third order dispersion about −637.88 ps3/km, high nonlinearity of 91.11 W−1 km−1. From overall simulation results, it can be expected that the suggested PCF will be an effective candidate in high bit rate long haul optical communication system as well as sensing applications.

The Effect of Mode Area and Refractive Index for Optical TE Mode Propagation in Hybrid LN/Si Electro-Optic Structure of Mach-Zehnder Modulator

We propose and analyse a silicon based hybrid modulator on the nano thin film of the lithium niobate or commonly known as silicon-on-insulator technology. The Mach–Zehnder stripe optical waveguide of electro-optical modulator operats at GHz frequencies with large bandwidth and low losses between electrical and optical frequencies.The design and simulation of Mach-Zehnder modulator is based on a hybrid integration platform of silicon and lithium niobate that satisfies a single mode condition. The Silicon stripe waveguide is of 0.6 μm thickness in a silicon on insulator (SOI) of width 15 um and 0.05 um thickness x-cut LiNbO3 thin film, all sets use the pulse laser deposition (PLD) method. The Optical electric field distributions and effective mode area in the optical-waveguides were studied and discussed in this designated waveguide.The relationship between the width of waveguides regions with effective mode index and effective mode area was investigated. At 0.6 um width of waveguide and 0.2 um thickness, the effective mode index 1.9802 was recorded while the effective mode area 0.144 um2 was monitored. This shows the decrement in both: the width and thickness of the waveguide with the effective mode index and effective mode area.

Feature Properties of Photonic Crystal Fiber with Hollow Core Filled Nitrobenzene

In this paper, a photonic crystal fiber (PCF) with core infiltrated with Nitrobenzene is proposed and investigated. Its feature properties as the effective refractive index, effective mode area, chromatic dispersion, and confinement loss have been numerically simulated. The obtained results show that characteristic quantities of PCF with core infiltrated with Nitrobenzene (PCF-N) having some advantages in comparison to PCF with core infiltrated with Toluene (PCF-T) at 1.55μm wavelength. For the purpose of supercontinuum generation, two optimal structures with lattice constants 2.0μm and 2.5μm with filling factors d/Ʌ = 0.3 are identified.

Numerical Analysis of the Characteristics of Glass Photonic Crystal Fibers Infiltrated with Alcoholic Liquids

The characteristics of PCF with various air hole diameters infiltrated with alcoholic liquids such as ethanol, methanol, propanol and butanol are numerically investigated. Based on the numerical results, we have analyzed and compare in detail the characteristics of these fibers including effective refractive index, effective mode area, dispersion and confinement loss for two case: the diameters and lattices constant of air holes are equal 1 µm and 5µm, 1.42µm and 3.26µm, respectively. The PCF infiltrated with ethanol and butanol showed better near zero flattened dispersion property at 1.42µm and 1µm wavelength respectively. With diameters and lattices constant of air holes equal 1.42μm and 3.26μm, the smallest dispersion of PCF filled with ethanol of 5.91075308 (ps.(nm.km)-1) and methanol of 19.3592474 (ps.(nm.km)-1). The highest ZDW of the PCF infiltrated with ethanol and methanol is 1.24604224µm and 1.22405714µm, respectively. Specially, the value of effective refractive index, effective mode area, dispersion and confinement loss decrease in an orderly manner from butanol, propanol, ethanol to methanol and all the alcoholic liquids’s cuvers of dispersion are flat and are very close to each other and near the zero dispersion curve in case the diameters and lattices constant of air holes are equal 1µm and 5µm. The proposed PCF shows a promising prospect in technology applications such as supercontinuum generation.