Large Negative Dispersion Research Articles

ASE suppression in Er3+ doped dual-core triangular lattice photonic crystal fibers (PCFs) for narrowband and broadband dispersion compensation for communication wavelength

In this article, silica based triangular lattice PCF has been investigated toward both narrowband and broadband dispersion compensation for application in the communication wavelength. A dual core structure is obtained by introducing two different air-hole diameters in the cladding of the PCF. Dependence of individual structural parameters toward high negative dispersion (both narrowband and broadband) has been investigated in details with multipole mode based solver. The numerical investigation exhibits narrowband of very large negative dispersion of −37,300ps/nm/km around the wavelength of 1550nm. Present investigation also reports broadband dispersion values varying from −800ps/nm/km to −2600ps/nm/km over a 200nm wavelength (1400–1600nm) range, and kappa values near 300nm, which matches well with standard single mode fiber. Using the principle of power transfer from the inner core to the outer core after the coupling wavelength, we have investigated possible design of ASE suppressed amplifier in which wavelengths after the coupling wavelength cannot be amplified as most of the power tunnel to the outer core, where doped ion does not exist.

Ultraflattened high negative chromatic dispersion over O+E+S+C+L+U bands of a microstructured optical fiber

This paper presents a large negative flattened dispersion with high birefringence for a very wide wavelength range by designing a new high index lead silicate (SF57) soft glass equiangular decagonal spiral microstructured optical fiber (DS-MOF). The bandwidth supports the second and third windows covering the O+E+S+C+L+U bands in the infrared region. The guiding properties of the DS-MOF are investigated by the finite-element method with a perfectly matched layer boundary. The proposed design is a suitable candidate for the application of residual dispersion compensation with maintaining polarization characteristics since it offers a high negative flattened dispersion of −(453 ± 7) ps⋅nm −1 km −1 with a high birefringence of the order 10 −2 for the wide wavelength range of 1.15 to 1.75 μ m. The DS-MOF has some circular air holes that make the fabrication process simple. In addition, the effects of changing the structural parameters by up to ±4% are also analyzed to ensure the accuracy during the fabrication process.

Design of a pentagonal photonic crystal fiber with high birefringence and large flattened negative dispersion.

Novel pentagonal photonic crystal fiber with high birefringence, large flattened negative dispersion, and high nonlinearity is proposed. The dispersion and birefringence properties of this structure are simulated and analyzed numerically based on the full vector finite element method (FEM). Numerical results indicate that the fiber obtains a large average dispersion of -611.9 ps/nm/km over 1,460-1,625nm and -474 ps/nm/km over 1425-1675nm wavelength bands for two kinds of optimized designs, respectively. In addition, the proposed PCF shows a high birefringence of 1.67×10-2 and 1.75×10-2 at the operating wavelength of 1550nm. Moreover, the influence of the possible variation in the parameters during the fabrication process on the dispersion and birefringence properties is studied. The proposed PCF would have important applications in polarization maintaining transmission systems, residual dispersion compensation, supercontinuum generation, and the design of widely tunable wavelength converters based on four-wave mixing.

Design of photonic crystal fiber with large negative dispersion and high nonlinearity

A modified hexagonal index guiding photonic crystal fiber made of pure silica with high nonlinearity and large negative dispersion is proposed and properties, including the nonlinear coefficient and dispersion, are numerically analyzed using the multipole method. Numerical results show that a nonlinear coefficient of 37.1W−1km−1 at 1.55μm and large negative dispersion of −104, −103 and −102psnm−1km−1 in O, E, S and L communication wavebands are achieved simultaneously. Moreover, impacts of the hole spacing and hole size on the nonlinear coefficient and dispersion are also investigated in detail.

Highly birefringent photonic crystal fiber with ultra-flattened negative dispersion over S + C + L + U bands.

We present a new cladding design for photonic crystal fiber (PCF) on a decagonal structure to simultaneously achieve ultra-flattened large negative dispersion and ultrahigh birefringence. Numerical results confirm that the proposed PCF exhibits ultra-flattened large negative dispersion over the S+C+L+U wavelength bands and average dispersion of about -558.96 ps/nm/km with absolute dispersion variation of 9.7 ps/nm/km from 1460 to 1675 nm (215 nm bandwidth). Moreover, ultrahigh birefringence of 0.0299 is also achieved at a 1500 nm wavelength.

A single mode hybrid cladding circular photonic crystal fiber dispersion compensation and sensing applications

In this paper, we propose a highly birefringent and highly nonlinear polarization maintaining single mode hybrid cladding circular photonic crystal fiber (HyC-CPCF). The proposed structure is extremely attractive for compensation of chromatic dispersion of standard single mode fiber (SMF) over 1360 to 1640nm wavelength band. Guiding properties are investigated using finite element method (FEM) with perfectly matched layer boundary condition. Simulation results confirm the possibility of large negative dispersion coefficient and relative dispersion slope of −650ps/(nmkm) and 0.0036nm−1, respectively, at 1550nm wavelength and effective dispersion coefficient of about ±0.5ps/(nmkm) from 1360 to 1640nm wavelength. The proposed fiber also demonstrates a high birefringence of order 2.1×10−2 at 1550nm wavelength that allows the fiber to maintain a single polarization. In addition, effective V parameter ensures the single mode operation of the designed fiber over the entire band of interest. To realize the practical feasibility, the sensitivity of the fiber dispersion properties to a ±2% of structural parameter variation around the optimum value is evaluated and reported. Moreover, effective dispersion and nonlinear coefficient are also presented and discussed. The proposed fiber can be a promising candidate in high speed transmission system for broadband dispersion compensation, sensing and nonlinear applications as well.

Soft glass spiral photonic crystal fiber for large nonlinearity and high birefringence

This paper presents a soft glass spiral photonic crystal fiber with circular air holes for achieving high birefringence, large nonlinearity and large negative dispersion. The material used here for designing the fiber is soft glass (SF-57). A central defect air hole is being introduced in the core for achieving high birefringence and for different ellipticity ratios the effect of various optical properties of a photonic crystal fiber are studied. The structure proposed has a high birefringence in the order of 10 –2 , high nonlinearity of 5828 W –1 km –1 and high negative dispersion of –1546.6 ps/nm·km at 0.850 μm. A numerical approach based on the finite element method is used for the design and simulation of the structure. Due to the optimization in the cladding air holes, the fiber can be used as polarization maintaining fibers, in dispersion compensation and other nonlinear applications.

一种拥有超大负色散的双芯光子晶体光纤

一种拥有超大负色散的双芯光子晶体光纤

Design and analysis of a photonic crystal fiber with four-hole unit

A novel photonic crystal fiber (PCF) based on a four-hole unit is proposed in order to meet the requirements of high birefringence, negative dispersion and confinement loss in fiber-optic communication. The proposed design has been simulated based on the full vector finite element method (FVFEM) and anisotropic perfectly matched layers (APML). Analysis results show that the proposed PCF can achieve a high birefringence to the order of 10−2 at the wavelength of 1.55μm, a large negative dispersion over a wide wavelength range and confinement losses lower than 10−9dB/m simultaneously, which has important applications in polarization-maintaining (PM) fibers, single-polarization single-mode (SPSM) fibers, dispersion compensation fibers and so on.

Design and Characterization of Highly Birefringent Residual Dispersion Compensating Photonic Crystal Fiber

A residual dispersion compensating octagonal photonic crystal fiber (OPCF), with an elliptical array of circular air-holes in the fiber core region, is proposed. The full-vector finite-element method with perfectly matched layer boundary is used as the analysis tool. It is demonstrated that it is possible to obtain large average negative dispersion of -562.52 ps/(nm · km) over 240 nm and -369.10 ps/(nm · km) over 630 nm wavelength bands for the fast and the slow axis, respectively. In addition to large negative dispersion, ultra-high birefringence, high nonlinearity, and zero-dispersion wavelengths with low confinement loss are also warranted. The proposed OPCFs would be a promising candidate for residual dispersion compensation, supercontinuum generation, and other applications.

Investigation on characteristics of W-type fiber with an inner cladding made of negative refractive index materials

A doubly clad optical fiber with an inner cladding made of negative refractive index material was proposed and the modes distribution, dispersion and time delay were investigated by fully vectorial numerical method. The results indicate that HE12 mode can be operated as a single mode, the cut-off frequency of modes shifts to low normalized frequency with increasing thickness of inner cladding made of negative index materials, large negative dispersion and time delay can be obtained and tailored by the inner cladding. These results provide theoretical basis for designing novel fibers or optical devices.

Designing an Ultra-Negative Dispersion Photonic Crystal Fiber with Square-Lattice Geometry

We have theoretically investigated the dispersion characteristics of dual-core PCF, based on square-lattice geometry by varying different parameters. The fiber exhibits a very large negative dispersion because of rapid slope change of the refractive indices at the coupling wavelength between the inner core and outer core. The dependence of different geometrical parameters, namely, hole-to-hole spacing (Λ) and different air-hole diameter (d), was investigated in detail. By proper adjustment of the available parameters, a high negative dispersion value of -47,500 ps/nm/km has been achieved around the wavelength of 1550 nm. Our proposed fiber will be an excellent device for dispersion compensation in long-haul data transmission as being thousand times more than the available DCFs.

Design of ultra large negative dispersion PCF with selectively tunable liquid infiltration for dispersion compensation

A systematic analysis of the dispersion characteristics of a selectively liquid-filled dual-core PCF by varying different geometrical parameters towards achieving ultra negative dispersion values around a desired wavelength has been carried out. The dependence of PCF parameters along with the infiltrating liquid upon dispersion has been investigated. Our analysis establishes that with the increase of Λ, the total dispersion is red-shifted with a reduction of the negative dispersion. Again, the dispersion is red-shifted but with an increment of negative dispersion and narrower FWHM for an increase of d. In contrary to the above dependence of Λ and d, with an increase of nL, the dispersion gets blue-shifted with an increase of negative dispersion at the cost of reduced FWHM. Our numerical study establishes a high negative dispersion of −52,100ps/nm/km around 1550nm through an optimized design. Three such designs of selectively liquid filled dual-core PCF demonstrating a negative dispersion from −28,700ps/nm/km to −52,100ps/nm/km around the wavelength of 1550nm with available practical liquids have been presented to demonstrate the effectiveness of the method. Our optimized structures demonstrate excellent tunable properties with temperatures for various optical communication systems based devices. Our proposed PCF will be an excellent candidate for dispersion compensation in long-haul data transmission as being thousand times more than the available DCFs. Our approach of dispersion engineering will be helpful for dispersion engineering related applications like true time delay instruments, Raman amplifier, ASE suppression, Four-wave mixing etc.

Design of hybrid photonic crystal fiber: Polarization and dispersion properties

A highly birefringent dispersion compensating hybrid photonic crystal fiber is presented. This fiber successfully compensates the chromatic dispersion of standard single mode fiber over E- to L-communication bands. Simulation results reveal that it is possible to obtain a large negative dispersion coefficient of about −1054.4ps/(nmkm) and a relative dispersion slope of 0.0036nm−1 at the 1550nm wavelength. The proposed fiber simultaneously provides a high birefringence of order 3.45×10−2 at the 1550nm. Moreover, it is confirmed that the designed fiber successfully operates as a single mode in the entire band of interest. For practical conditions, the sensitivity of the fibers dispersion properties to a ±2% variation around the optimum values is carefully studied and the nonlinearity of the proposed fiber is also reported and discussed. Such fibers are essential for high speed transmission system as a dispersion compensator, sensing applications, fiber loop mirrors as well as maintaining single polarization, and many nonlinear applications such as four-wave mixing, etc.

From slow to fast light in amplified negative refraction using atomic coherence assisted by an incoherent pump

We propose and demonstrate a scheme to realize large negative refraction dispersion when a probe field is amplified by cooperation between a coherent field and an incoherent pump. The probe pulse can propagate either subluminally or superluminally in the left-handed amplification medium by modulating parameters of the coherent and incoherent fields.

Chalcogenide glass square photonic crystal fibre with large negative dispersion and high non-linearity

We propose a square structure, square lattice photonic crystal fibre (PCF) with square air-holes in its cladding. We consider chalcogenide (As2Se3) glass as the material of PCF. Chalcogenide glass has a large refractive index and high non-linearity compared to silica glass. A large negative dispersion of around -5473.7 ps/(nm-km) at 0.85 mum is obtained. A high non-linearity of 4813.5 W-1km-1, at telecom wavelength of 1.55 mum is observed. This PCF can be used for dispersion compensation as well as non-linear applications such as non-linear switching, optical regeneration, wavelength division multiplexing, frequency conversion, super-continuum, etc.

Chalcogenide Glass Square Photonic Crystal Fibre with Large Negative Dispersion and High Non-Linearity

We propose a square structure, square lattice photonic crystal fibre (PCF) with square air-holes in its cladding. We consider chalcogenide (As2Se3) glass as the material of PCF. Chalcogenide glass has a large refractive index and high non-linearity compared to silica glass. A large negative dispersion of around -5473.7 ps/(nm-km) at 0.85 /um is obtained. A high non-linearity of 4813.5 W−1km−1, at telecom wavelength of 1.55µm is observed. This PCF can be used for dispersion compensation as well as non-linear applications such as non-linear switching, optical regeneration, wavelength division multiplexing, frequency conversion, super-continuum, etc.

Design of polarization-maintaining photonic crystal fibre for dispersion compensation over the E+S+C+L telecom bands

We investigate numerically a defected-core hybrid photonic crystal fibre (H-PCF) with a circular core and a rectangular-shaped cladding, which is designed for compensation of residual dispersion over a wide wavelength range. Our simulation results testify that this H-PCF exhibits a large negative dispersion (- 868 ps/(nm km)) over the E+S+C+L telecommunication bands, with the relative dispersion slope perfectly matching that of a single-mode fibre at the operating wavelength 1550 nm. The H-PCF reveals the birefringence 1.06×10 -2 at the operating wavelength. In order to evaluate the sensitivity of optical properties of our H-PCF, we study the effect of variations of its parameters as large as ±2% from their optimal values. Due to its specific characteristics, the H-PCF suggested in this work can be considered as an excellent candidate for compensating dispersion, maintaining a single polarization in the optical fibre transmission systems, and numerous optical sensing applications.

Highly nonlinear and highly birefringent dispersion compensating photonic crystal fiber

This paper presents an optimum design for highly birefringent hybrid photonic crystal fiber (HyPCF) based on a modified structure for broadband compensation covering the S, C, and L-communication bands i.e. wavelength ranging from 1460 to 1625nm. The finite element method (FEM) with perfectly matched layer (PML) circular boundary is used to investigate the guiding property. It is demonstrated that it is possible to obtain broadband large negative dispersion, and dispersion coefficient varies from −388.72 to −723.1psnm−1km−1 over S, C and L-bands with relative dispersion slope (RDS) matched to that of single mode fiber (SMF) of about 0.0036nm−1 at 1550nm. According to simulation, a five-ring dispersion compensating hybrid cladding photonic crystal fiber (DC-HyPCF) is designed that simultaneously offers birefringence of order 3.79×10−2, nonlinear coefficient of 40.1W−1km−1 at 1550nm wavelength. In addition to this, effective area, residual dispersion, and confinement loss of the proposed DC-HyPCF are also reported and discussed.

A new circular photonic crystal fiber for effective dispersion compensation over E to L wavelength bands

This paper presents a new circular photonic crystal fiber (C-PCF) for effective dispersion compensation covering E to L wavelength bands ranging from 1360-1625 nm. To investigate its guiding properties, finite element method (FEM) with a perfectly matched layer absorbing boundary condition is used. From our numerical simulation, it is found that the designed C-PCF simultaneously shows a large negative dispersion of about -248.65 to -1069 ps/(nm.km) over E to L wavelength bands and a relative dispersion slope (RDS) exactly equal to that of a single mode fiber (SMF) at 1.55 µm wavelength. It is also found that residual dispersion after compesating 40 km long SMF is within ±62 ps/nm which ensures application of C-PCF in high speed WDM system. Besides, dispersion slope, slope compensation ratio, effective area and confinement loss of the proposed C-PCF are also evaluated and discussed.