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This work presents a numerical model of a photonic crystal fiber made up of chalcogenide glass for highly coherent supercontinuum generation in the mid-infrared spectral region. Numerical simulations based on the finite element method have been performed. An optical dispersion engineering technique has been adopted to minimize the dispersion effect at pump wavelength by alteration of geometrical parameters of designed fiber. We have selected two optimal structures from the simulation results to analyze the nonlinear characteristics and supercontinuum generation. The first fiber, #F 1 with a lattice constant of 1.0 μm and a filling factor of 0.3 operates in all-normal dispersion, providing the spectrum SC in the range of 2.4 μm to 8.0 μm with a pump wavelength of 5.0 µm, pulse duration of 90 fs, and peak power of 6 kW. Meanwhile, fiber #F 2 has anomalous dispersion regimes. With a peak power of 2 kW, this fiber produces a wide SCG with spectral ranges of 4.4–16 μm. The proposed structures are promising for applications in low-peak power all-fiber optical systems. [ABSTRACT FROM AUTHOR]

In this work, a unique Photonic Crystal Fiber based on the Localized Surface Plasmon Resonance is designed for cancer cell and chemical detection. A novel combination of plasmonic materials namely Aluminum doped Zinc Oxide (AZO) and a Silver (Ag)-TiO 2 bilayer is deposited along two horizontal slits to achieve resonance at two separate wavelengths within a particular refractive index. The sensor achieves resonance at different wavelengths along x and y polarizations, broadening analyte detection for a specific RI. Two modes of operation are introduced: mode-1 is optimized to achieve the highest Amplitude Sensitivity (AS), and mode-2 to maximize the Wavelength Sensitivity (WS). The mode-1 is examined for a range of RI from 1.35 to 1.42, while the other is 1.35–1.41. The sensor can showcase an AS of 4641.51 RIU−1 for Ag at RI 1.36, which is the highest value of AS found in literature when Ag is used as plasmonic material, while AZO achieves a high AS of 3204.51 RIU−1 at 1.41 RI. A highest WS of 10,320 and a Double Peak Shift Sensitivity (DPSS) of 8089.5 nm/RIU at 1.41 RI is obtained using the mode-2 configuration with a wavelength resolution of 9.69 × 10−6 RIU and a maximum FOM of 568.22 RIU−1. The sensor is examined to investigate skin, cervical, and blood cancer by analyzing the Basal, HeLa, and Jurkat cells, which yielded superior outcomes when detected using AS among relevant works. In addition, the detection of various industrial chemicals like acetone, hexane, isopropanol, and ethanol is also manifested in this study. [ABSTRACT FROM AUTHOR]

A new photonic crystal fiber is proposed for the transmission of more orbital angular momentum modes with a rectangular air hole arrangement to increase the cladding air-filling rate. The results reveal that the fiber can support 190 orbital angular momentum modes in the C+L band, with the topological charge ordering up to 48, and the effective refractive index difference between adjacent eigenmodes is above 10−3. The effective mode area of all the eigenmodes is larger than 208.02 μm2, the nonlinearity coefficient is less than 0.43 W−1∙km−1, the confinement loss reaches up to 10−12-10−8 dB/m, the dispersion is flat and the minimum dispersion change is 3.15 ps∙nm−1∙km−1, with mode purity greater than 97.4%. Compared to existing typical orbital angular momentum transmission photonic crystal fibers, this fiber can support more orbital angular momentum modes for most purposes with lower nonlinearity coefficient, higher mode purity, better propagation characteristics but simpler structure. The highest nonlinearity coefficient is reduced by at least 0.3 W−1∙km−1 compared to existing typical orbital angular momentum transmission photonic crystal fibers. The effect of fabrication errors on the transmission quality of orbital angular momentum modes is also discussed, and the results reveal that the effect on mode transmission quality is small at 1–2% variations of air holes. Therefore, this photonic crystal fiber is promising in high-capacity communication systems. [ABSTRACT FROM AUTHOR]

After COVID-19 healthcare shareholders are more attentive to the different solutions. One of the critical illnesses cancer becomes more changeling after this situation. There are different techniques are suggested as well as developed for detection of the cancer. People of still looking for low-cost solutions for cancer detection. The Photonic crystal fiber is a versatile device utilized for various bio-sensor applications. The double V-groove design proposed in this research offers significant advantages, including enhanced sensitivity, accurate detection capabilities, and easy fabrication. The surface plasmon resonance-based PCF sensor, with its unique V-shaped structure, not only addresses the limitations of conventional prism-based SPR sensors but also opens new possibilities for remote sensing applications. The proposed article is based on the double V-groove photonic crystal fiber (PCF)-based sensor for cancer detection. The Q factor is 155 and the figure of merit (FOM) is 6000 RIU − 1 and sensitivity of the proposed sensor is 60 μ mRIU − 1 has obtained. This sensor provides a wide range of detection based on the refractive index (RI) profile of the infected blood. [ABSTRACT FROM AUTHOR]

An ultra-broadband, very low peak power supercontinuum source is proposed based on a novel benzene-filled structured photonic crystal fiber. The modification of the structural parameters has been highly effective in improving dispersion properties, an ultra-flat all-normal dispersion is achieved with fluctuations of ±1.174 ps/(nm.km) in the 0.458 µm wavelength region. Three fibers with suitable optical properties best meet the requirements of supercontinuum generations with low peak power based on numerical simulation results. With anomalous dispersion regime, the first fiber offers the supercontinuum spectra in the mid-infrared region spanning from 0.784 µm to 3.973 µm (2.539 µm bandwidth at 30 dB) using laser pulses excited at 1.55 µm has a peak power of 150 W. A pulse with a peak power of 280 W propagates in a 5 cm length of the second fiber results in a supercontinuum spectrum covering from 0.744 µm to 1.859 (bandwidth 1.063 µm at 30 dB) at a pump wavelength of 1.3 µm with all-normal dispersion regime. A smooth, highly coherent supercontinuum spectrum spanning from 0.843 µm to 2.517 µm (bandwidth at 30 dB of 1.608 µm) is achieved when the third fiber has all-normal ultra-flat dispersion profile pumped at 1.75 µm wavelength with laser pulse peak power of 350 W. With very low peak power, these proposed three-fiber based broadband supercontinuum sources could be a low-cost alternative to traditional glass-core fiber, which has great potential for mid-infrared spectroscopy. [ABSTRACT FROM AUTHOR]

An electrically tunable birefringence in a nanophotonic waveguide based on MgZnO-CdZnO semiconductor heterojunction is numerically proposed. Electrical control is realized with two-dimensional electron gas (2DEG) at the interface of ZnO based heterojunction and is used to control the polarization. The waveguide is engineered to enhance interaction of guided optical mode(s) with 2DEG providing us with a wide tuning in modal birefringence. We perform numerical analysis of phase and polarization characteristics of 2DEG based nanophotonic waveguide. Electrical tuning of 0.0112 in modal birefringence is reported by varying the applied voltage from 0 Vto − 10 V. The proposed device also exhibits voltage variable optical phase modulation in both TE and TM polarizations. The proposed work can be utilized in applications where integrated photonic devices with variable polarization control are desirable. [ABSTRACT FROM AUTHOR]

This research article provides a comprehensive analysis of a localized surface plasmon resonance (LSPR) based sensor, which operates in the visible to near-infrared region and uses a distinctive combination of two metals, ITO and Au as the plasmonic layers to achieve exceptional sensitivity. The wavelength spectrum that this sensor can now measure has been extended by combining these two materials in the RI region of 1.30 to 1.41, allowing the sensor to function in diverse fields such as bioimaging, biosensing, photocatalysis etc. A distinct and novel characteristic of the sensor which is termed as double polarization peak shift sensitivity (DPPSS) is proposed in this manuscript indicating the detection of resonance peak shift in both x-pol and y-pol simultaneously. DPPSS serves as the evaluative parameter for assessing the performance of the sensor. After optimizing all the structural parameters of the proposed sensor on the basis of DPPSS, it is found that the ultimate DPPSS value is 19560 nm/RIU and the maximum wavelength sensitivity is 19630 nm/RIU. Along with having a great sensitivity, the suggested sensor is fabrication friendly. The proposed research serves as a foundation for a thorough exploration of the LSPR phenomena for PCF in double metal scenario. [ABSTRACT FROM AUTHOR]

In this research, an all-normal-dispersion mode-locked photonic crystal fiber laser (MLPCFL) is simulated. Three types of large-pitch PCFs with a small value of self-phase modulation coefficient are introduced and their fundamental characteristics are numerically investigated. They are then employed in the laser cavity and the performance of MLPCFL using these three different large-pitch PCFs is compared. According to the simulation results, as the hole-to-hole distance gets larger, the pulse spectrum profile changes from M-shape to parabolic and the temporal width of the pulses is also increased. Additionally, the simulation demonstrates that the presented laser has the potential to generate pulses with an energy of 450 nJ, if a 5 m length of passive PCF with Ʌ = 20 µm (Ʌ is hole-to-hole distance) is incorporated into the laser cavity. The results reveal that, by inserting a 1 m-long Yb-doped PCF with Ʌ = 20 µm at the output port of the laser, it becomes possible to generate pulses with an energy of 45 μJ and a peak power of 2.47 MW. The chirped output pulses from the amplifier are compressed after passing through the dispersion delay line and resulting in a reduction of the FWHM to 150 fs. [ABSTRACT FROM AUTHOR]

We investigate a defective core photonic crystal fiber for broadband continuum generation. Different geometries of fiber design are discussed to emphasize the role of a defect in the fiber characteristics. The idea of incorporating a defect in the core enable an additional degree of design freedom to tailor the fiber parameters. Particularly, we identify that by properly choosing the size of the defect and air hole size one can realize suitable fiber design for various nonlinear applications. Out of several fiber designs, we recognize that designing fiber with minimum positive dispersion along with a large nonlinearity coefficient is a potential candidate for supercontinuum generation. The results of numerical simulation of the broadband continuum at different parameter settings are analyzed and compared with the conventional counterpart. In the similar simulation environment, the continuum realized in the proposed defective core photonic crystal fiber is significantly broader than the fiber without defect. Thus, this hybrid fiber design can be a new class of fibers for the future generation of broadband sources. [ABSTRACT FROM AUTHOR]

A lower-birefringence peak method is used to investigate a new birefringence photonic crystal fiber (PCF) based on the surface plasmon resonance (SPR) sensor with an asymmetrical configuration. The novel method can determine the resonance wavelength and resonance intensity by the appearance of the lower peak and overcome deficiencies of the reported zero-birefringence point method. Upper and lower gaps are designed in the air holes to enhance the birefringence of the sensor as well as coupling efficiency between the plasmonic mode and core-guided mode. The dependence of the sensing performance on the structure parameters is discussed considering the depth of penetration of the evanescent wave and location of light confinement analysis. A maximum spectral sensitivity of 16,700 nm/RIU can be obtained in a broad refractive index (RI) detection range from 1.33 to 1.42 and the corresponding RI resolution is 5.99×10−6RIU. [ABSTRACT FROM AUTHOR]

• A golden spiral photonic crystal fiber using tellurite glass is proposed for supercontinuum generation. • Proposed 5.5 cm long fiber has generated a broad supercontinuum, spanning 1000–5500 nm in infrared wavelength region. • Such fibers can be advantageous in infrared spectroscopy, optical coherence tomography, cancer detection, and sensing. In this paper, we have numerically designed a golden spiral photonic crystal fiber using tellurite glass for supercontinuum generation. Dispersion engineering technique has been used for the optimization of geometrical parameters of the fiber. At a pump wavelength of 1.35 μm, the proposed fiber offers the high value of nonlinear coefficient as 884 W−1. km−1 and low effective mode area as 3.79 μm2. An ultra-broadband supercontinuum spectrum ranging 1000 – 5500 nm has been generated with a bandwidth of 4500 nm using designed fiber of length 5.5-centimeters long pumped with few femtosecond laser sources in the infrared wavelength region. [ABSTRACT FROM AUTHOR]

• Computational model of photonic crystal fibers in silica glass for near-infrared supercontinuum generation has been proposed. • At pump wavelength of 1300 nm, a flat-top dispersion profile has been obtained with very low dispersion value in anomalous region. • An ultra-broadband supercontinuum spanning, from 0.67 μm up to 2.4 μm can be easily achieved by proposed fiber of 37 cm length in near-infrared wavelength region. We report computational modeling of photonic crystal fibers in silica glass for near-infrared supercontinuum generation. Optical parameters like chromatic dispersion, nonlinearity and the effective area of the fundamental mode have been computed and tailored by using a full vectorial finite element method. At pump wavelength of 1300 nm, a flat-top dispersion profile has been obtained with very low dispersion value + 0.6402 ps/nm/km in the anomalous region. The reported structure offers high nonlinear coefficient 26.27W−1. km−1with effective mode area 4.78 μm2 at the pump wavelength. An ultra-broadband supercontinuum spanning, from 0.67 μm up to 2.4 μm can be easily achieved by the proposed fiber of 37 cm length using a 63 fs secant laser pulse source with 8 kW peak power in the near-infrared wavelength region. Such type of fiber can be advantageous in the field of near-infrared spectroscopy, optical communication, gas sensing, medical, frequency metrology, optical coherence tomography, and food quality control. [ABSTRACT FROM AUTHOR]

In this work we calculate the linear dependence with the temperature of the modes located in a one-dimensional photonic crystal with two defects, when considering the oblique incidence of a light beam with TM polarization. We find that as the temperature increases, the localized modes undergo a shift towards regions of shorter wavelengths. Additionally, we report that by increasing the angle of incidence, the defective modes present a shift towards regions of shorter lengths. [ABSTRACT FROM AUTHOR]

The imaging properties of the Maxwell's fisheye (MFE) lens makes it a viable candidate to implement power coupling between different types of waveguides. A coupler based on the MFE lens is designed to couple a square lattice photonic crystal to a triangular lattice one. The MFE lens is implemented as ring-based multilayer and graded photonic crystal (GPC) structures. The performance of the ring-based MFE lens is better than the GPC-based one in the C-band of optical communication. The proposed ring-based MFE coupler has a footprint of 3.62 × 3.62 μ m and covers the entire C and U bands. The S and L bands are partially covered. The average insertion loss of 0.1 dB and the maximum return loss of -11 dB in the C-band is achieved. [ABSTRACT FROM AUTHOR]

The research of polarization-maintaining photonic crystal fiber with temperature insensitive characteristic is one of the important methods to solve the temperature dependence problem in the engineering application of an optical sensing system. This paper presents a new kind pentagonal polarization-maintaining photonic crystal fiber, and its polarization characteristic under the influence of temperature was analyzed based on the theory of the thermal expansion effect and thermal optic effect. The results show that the temperature dependence of the proposed fiber is significantly lower than that of the hexagonal photonic crystal fiber with the same design parameters at -50℃˜80℃. It has potential application value in some optic fiber sensing systems that need high precision and working stability under the turbulence of temperatures, such as fiber optical voltage sensor, fiber optical current sensor and fiber optic gyroscope. [ABSTRACT FROM AUTHOR]

In this paper, a novel Y-shaped photonic crystal circulator based on a photonic crystal gradient changing width waveguide is proposed. The gradient changing width waveguide is constructed by triangular lattice photonic crystals with dielectric cylindrical posts. Simulation results show that the waveguide has well transmission characteristics with low ripple and high efficiency. The Y-shaped photonic crystal circulator is envisaged based on the waveguide with three ferrite posts in waveguide junction. Insertion loss and isolation of the circulator are 0.0028 dB and 53.36 dB respectively, which were theoretically analyzed through FEM method. [ABSTRACT FROM AUTHOR]

A high birefringence and low confinement loss squeezed fluoride photonic crystal fiber (PCF) is proposed with two special elliptical air holes in the cladding. This fiber is made of Fluoride glass and it has high birefringence and low confinement loss. The confinement loss of x - and y - polarization modes at 1.064 μm is under 4.74 × 10−8 dB/m. And the confinement loss of x - and y - polarization modes at 1.310 μm is 9.06 × 10-6 dB/m and 5.70 × 10-7 dB/m, respectively. This fiber has good performance at 1064 nm and 1310 nm. The birefringence value can reach 4.85 × 10-2 at 2 μm. [ABSTRACT FROM AUTHOR]

This paper proposes a mid-infrared (mid-IR) Ge 20 Sb 15 Se 65 -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, D 1 = 2.2 μm, and d 1 = 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. [ABSTRACT FROM AUTHOR]

A simple method is proposed to measure the total rotation of polarization axis caused by both internal and external factors during the fabrication process in polarization-maintaining fibers (PMFs). The method is suitable for any kind of PMF, and avoids the additional clamping-induced rotation of fiber with assistance of gravity. Based on this method, a polarization-maintaining photonic crystal fiber (PM-PCF) and a conventional panda PMF used in fiber-optic gyroscope (FOG) are tested. The experimental results provide foundation for the analysis of fiber quality and magnetic-induced bias error in a FOG. © 2018 The Author(s). [ABSTRACT FROM AUTHOR]

Photonic crystal fibres (PCFs) have attained popularity in designing compact optical devices utilized in optical networks and optical sensing systems. The PCFs have the potential to achieve a minimum dispersion, low confinement losses, high power, high birefringence that are more suitable for the sensor domain applications. In this paper, we proposed a hybrid photonic crystal fibre (HPCF) with five layers elliptical air–holes and a ring waveguide at inside, which achieved the minimum power of 0 dB at 1.03 μm and maximum power of ˜0.11 W (i.e. −18 dB) at 1.55 μm wavelength and in the frequency domain, these values are obtained at ˜96.70 THz for minimum power and ˜290.7 THz for maximum power. The suggested structure also provides the ˜5.1 W/m maximum power cross cut at 154 mesh point and ˜0.11 W peak power at 1.55 μm which is zero dispersion wavelength and it will support narrow band gaps of 0.142–0.152, 0.148–0.158, and 0.110−0.112 for transverse electric (TE), transverse magnetic (TM) and hybrid mode respectively. Several designs are reported for the PCF, but most of the design have the different type of air holes or variable size of air holes which seems like some complex structure inside. The proposed design consists of equal shape and size air holes that are symmetrical and a simple ring structure at the centre. This design will be easy to fabricate. [ABSTRACT FROM AUTHOR]

A photonic quasi-crystal fiber (PQF) with high birefringence based on ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN) is described. There are two elliptical air holes in the core to increase birefringence and the outer air hole array has a twelve-fold Stampfli-type quasi-crystal structure. ZBLAN reduces absorption loss in the infrared region resulting in higher birefringence. The birefringence and confinement loss of the PQF are analyzed numerically by the full-vector finite element method. Birefringence is higher than that of conventional polarization-maintaining fibers due to the two elliptical air holes in the center and reaches the maximum of 4.15×10−2 at a wavelength of 2 μm. The novel structure has great potential in high-performance optical devices. [ABSTRACT FROM AUTHOR]

In quasi pattern, photonic crystal fiber (PCF) with Ge 20 Sb 15 Se 65 rectangular core is modeled. In this article, few optical properties of PCFs like power fraction, nonlinearity, effective mode area, birefringence, beat length, waveguide dispersion are obtained using finite element method (FEM). The proposed structure demonstrates significant effect on few optical properties for two polarization modes. It produces a high nonlinearity of 6.161 × 103 W−1Km−1and birefringence of 1.46 × 10−1 inside infrared region (IR). This proposed structure may play a vital role in multitasking applications. [ABSTRACT FROM AUTHOR]

Silicon is a widely used material due to its strong properties especially low loss and high nonlinearity in the wavelength range 1.2–6 μm. Also, photonic crystal fibers (PCFs) have been extensively involved in producing spectral light broadening in the literature. Here we report supercontinuum generation (SCG) over the wavelength range 1000–3000 nm from a silicon-core/silica-cladding PCF with length of 10 mm. The proposed PCF produces light broadening at both telecommunication wavelengths 1.3 μm and 1.55 μm as well as at the zero dispersion wavelength (ZDW = 2.0 μm). The effect of altering the core size, pump power and crystal parameters on the generated spectra is discussed. It is found that the SC spectra wide is increased by 715 ± 50 nm by increasing the pump wavelength from 1.3 μm to 2.0 μm. Further, the achieved SC spectra with broadening bandwidths of 892–1659 ± 50 nm has more than double the broadening of various silicon on insulator (SOI) waveguides with bandwidths range 330 nm–990 nm. [ABSTRACT FROM AUTHOR]

A dual core photonic crystal fiber (DCPCF) consisting single analyte channel is proposed in this article for the detection of petrol adulteration. The sensing probe is numerically studied using finite element method. The adulterated petrol sample is infiltrated in circular analyte channel which is situated at the center of the fiber between two solid light guiding cores. The mode coupling between these two cores as well as sensitivity of the designed probe are investigated by varying adulteration level of petrol. Also the structure is optimized step by step. The numerical simulation result shows very high sensitivity of 20,161.2 nm/RIU for practically usable small probe. A portable adulteration detection sensor can be manufactured using this simple structured DCPCF probe which will be useful to study environmental pollution, maintaining long engine lifetime, save revenue. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a new method to improve bit-rate of all-optical logic gate. At first, we make some changes in conventional photonic crystal waveguides (CPCW), which improve bit-rate of CPCW. We found by changing hole's diameter near defect, the bit-rate can be varied via hole's diameter variations. So, by finding maximum bit-rate in optimized photonic crystal waveguides (OPCW) and applying it in to an all-optical logic gate, the improvement can be seen. This can be achieved by first, finding the best bit-rate of OPCW then, applying OPCW in to an all-optical logic gate to find best answer for all optical logic gate, which considers this structure works functional. At the end, The results show that bit-rate of all-optical logic gate improved from 0.976 Tbit/s to 1.52 Tbit/s. [ABSTRACT FROM AUTHOR]

Abstract The article includes the greater effort such as quasi Photonic crystal fiber (PCF) with tellurite elliptical core structure is numerically investigated. The performances of the new form of PCF are inferred by calculating the desired optical parameters. As a whole, the PCF provides a significant effect on optical properties for two different modes. This model provides a high nonlinearity of 1.54 × 104 W−1Km-1 and power fraction of 98.64% at the wavelength of 0.6 μm. This proposed model promises for better impact in sensing, different type of imaging applications, signal processing and nonlinear applications. All the numerical calculations are carried out by employing finite element method (FEM). [ABSTRACT FROM AUTHOR]

Abstract The one dimensional photonic crystals (1DPCs) that have both the permittivity and permeability varying periodically along the same direction are analyzed theoretically using the coupled-mode theory. The approximate band edge frequencies, center frequencies, and the bandgaps are derived for the axial propagation. The results are elegant generalization of the corresponding results of the dielectric 1DPCs. The approximate bandedge frequencies obtained were found to have good agreement with those obtained by the transfer matrix method. [ABSTRACT FROM AUTHOR]

Highlights • PCF based UV torch is disclosed in this research. • The principle of investigation is based on field distribution in the fiber. • Plane wave expansion method is used to show output result. Abstract Though photonic crystal fiber has been exhibiting an exhilarating application since a couple decades, the current communication divulges an another noteworthy upshot vis-à-vis Ultra Violet (UV) signal from Visible light. The photonic crystal fiber is taken as square type silicon based photonic crystal, where nature, position and configuration are mainstay of this research work. The principle of investigation of present study is based on the distribution of electric field in the said suggested fiber in such way that emerging signal from such fiber lies with the range of UV signal. Finally the proposed device acts as fiber based torch light, which could be used for UV applications. [ABSTRACT FROM AUTHOR]

Abstract We have numerically investigated the influences of asymmetrical geometric structures on the birefringence of the index-guiding photonic crystal fiber (IG-PCF), by the finite element method. The structure of a reported highly birefringent (HB) PCF with artificial defect in the core is modified to destruct the symmetry. Our proposed structural modifications include elliptical air hole cladding, squeezing lattice of air holes, rotational elliptical air holes, and horizontally shifted air holes, in the cladding. It is found that the birefringence is sensitive to the modifications in different cases due to the different mechanisms. For 1550 nm wavelength, the optimized birefringence can be obtained to be 0.0328 by the elliptical air holes with the major semi-axis in the direction of the long side of the rectangular core region. Furthermore, for the HB-PCF by the asymmetric core shape, the structural factor restricting the further increase of birefringence is that continuous increase of asymmetry leading to the multi-core transmission. It seems to be that This work is not only a proposing of the optimal design of HB-PCF, but also a reference of founding the essence of geometric birefringence. [ABSTRACT FROM AUTHOR]

Abstract The present communication deals with a metamaterial based single photonic crystal fiber (PCF) to realize absorber, reflector, and transmitter application. The simulation studies which is made with the help of plane wave expansion method infers that the configuration including lattice spacing and diameter of air holes of the photonic crystal fiber along with the nature of the material play an important role to realize the aforementioned applications. Furthermore, the novelty of this work is that single PCF structure bestows absorber, reflector, and transmitter. [ABSTRACT FROM AUTHOR]

Abstract The alloy coatings were manufactured by laser cladding on Q235 mild steel. Coatings with different Cr content consisted of different phases but contains common phases Cr, Cr 2 Ti and NiTi. With different Cr content, the microstructure of coating with 15% Cr (15-Coating) was different from that of coating with 30% Cr (30-Coating) and coating with 45% Cr (45-Coating), while that of 30-Coaintng and 45-Coating was similar. The hardness of coatings were significantly increased in comparison with that of substrate, and the maximum micro-hardness of coatings was more than 4 times as high as substrate. The wear resistance of coatings were improved dramatically compared with the substrate. With increase of Cr content, the hardness and wear resistance of coatings were both reduced. [ABSTRACT FROM AUTHOR]

Abstract In this work, we report a design of hexagonal photonic crystal fiber (PCF) with eight hexagonal rings with modified air hole size at the innermost ring. We analyze and compare the major optical parameters of a PCF such as dispersion and nonlinearity over the span of wavelength ranges from 800 nm to 1600 nm at different core diameters. The designs exhibit a high nonlinearity of 220 W−1 km−1 and 116.76 W-1 km−1 at 800 nm for supercontinuum generation in designed PCF and along the dispersion in negative characteristics about −650 ps/nm.km at 1310 nm with two zero dispersion wavelengths at 864 nm and at 1484 nm are numerically studied. In addition, we investigate the numerical modeling of supercontinuum (SC) generation in the designed PCFs and nearly 600 nm using 50 fs pulse with 2 kW pump power at 800 nm spectrum have been observed. [ABSTRACT FROM AUTHOR]

Abstract We propose and investigate a temperature sensor based on Sagnac interferometer with liquid crystal (LC) photonic crystal fiber (PCF) by finite element method (FEM). LC E7 which is anisotropic under electrical field is designed to be infiltrated into the cladding air holes of PCF. The birefringent PCF is then launched into a Sagnac interferometer. The interference spectrum of the Sagnac interferometer is influenced by the thermal effect of LC E7 and thus could be used to measure the temperature. The simulation results show that the temperature measuring sensitivity and resolution reach to 15 nm/K and 6.7E−4 K in the range of 290–320 K. The measuring range and sensitivity could be modified further by optimizing the PCF structure parameters. [ABSTRACT FROM AUTHOR]

Abstract All optical NOT and NOR logic gates using structures based on linear photonic crystal ring resonator (LPhCRR) are proposed in this paper. The switching function of the proposed gates can be obtained at very small power levels as it relies on the interference effect. Moreover, their functioning is possible with wide range of input powers and tolerant to input power fluctuations (as those work in linear optics regime). Optical behavior of the purposed structures is demonstrated by using Two Dimensional Finite Difference Time Domain (2DFDTD) method and dispersion diagram is extracted by Plane Wave Expansion (PWE) method. Performance of the proposed structures is found to be very good in terms of response time and contrast ratio. [ABSTRACT FROM AUTHOR]

Abstract A survey of recent investigations on ocean sensors is carried out with a specific focus on fiber optic sensing methods, materials for fabricating sensor head and sensor performance. Four categories of fiber optic sensing structures, including interferometer, fiber grating, photonic crystal fiber, and surface plasmon resonance are reviewed. These techniques measure physical and chemical variations of sensitive optical fibers and reveal changes in properties of the optical signal when exposed to the ocean environment. Advantages and disadvantages of all the sensing schemes are discussed and compared. Hybrid sensors that combine different optical sensing techniques are also discussed. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the forward Brillouin scattering frequency shift of step-index fibers and photonic crystal fibers (PCFs) with different core diameters is investigated by numerical simulation. The result shows that, multiple Brillouin scattering peaks with the shift range from 20 to 800 MHz are generated in the step-index fibers. With the core diameter changing, the Brillouin scattering frequency shift has no change, but the scattering efficiency is different. In the PCFs with periodic air holes, there are a few dominant peaks. The frequency shifts vary with the core diameter changing. For the core diameter of 11.6 μm, there are three peaks at 327.39, 556.48 and 824.14 MHz, respectively. When the core diameter decreases to 2.32 μm, the frequency shifts of forward Brilloun scattering are 1.619, 2.779 and 4.123 GHz, respectively. The forward Brillouin frequency shifts increase with the core diameter decreasing. The results will be useful for the research on the mechanism of forward Brillouin scattering and have potential applications on the field of nonlinear fiber optics. [ABSTRACT FROM AUTHOR]

Abstract Photonic Crystal (PC) based optical devices have been widely explored in recent era due to their capability of miniaturization and large-scale integration of optical and opto-electronic devices. In this paper, two dimensional PC based Single Loop, Double Loop (Horizontal) and Double Loop (Vertical) Ring Resonators using hexagonal lattice structure is designed and analyzed. It reports the Discrete Fourier Transform (DFT) analysis using Finite Difference Time Domain (FDTD) method and calculates the Photonic Band Gap (PBG) using Plane Wave Expansion (PWE) method. The comparative analysis of three configurations based on Q factor reports the outperformance of double loop photonic crystal ring resonator (PCRR) with lattice constants A = 30 and C = 30 at 1550 nm with Q factor 17,000. The Q factor for double loop horizontal and single loop structure is 16,300 and 15,500 at 1550 nm. [ABSTRACT FROM AUTHOR]

Abstract A high sensitive dual-parameter sensor is proposed by combined use of modal interference and directional coupling in magnetic fluids (MF) infiltrated photonic crystal fiber (PCF). Based on the dependence of the MF refractive index on temperature and magnetic field, the rapid responses of loss spectra and interference spectra are monitored together to achieve concurrent measurement of temperature and magnetic field. Moreover, the dual-parameter matrix method is utilized to solve the cross-sensitivity problem. The interference spectra indicate a high temperature sensitivity of 0.21nm/°C and magnetic-field sensitivity of −0.78nm/mT, while the loss-spectra show the high temperature sensitivity of 0.65nm/°C and magnetic-field sensitivity of −2.46nm/mT. The simple and reliable sensor has the advantages of high sensitivity, good linearity and immunity to cross-sensitivity, offering new approaches for multi-parameter measurement. [ABSTRACT FROM AUTHOR]

Abstract An octagonal photonic crystal fiber polarization beam splitter with gold-plated film is proposed. The polarization beam splitter characteristics are studied by optimizing the gold film thickness, the cladding air hole diameter and the air hole spacing. At the communication wavelength of 1.55 μm, the coupling ratio can reach the ideal value of 2. Under the optimum geometric parameters, the curve of the coupling length with the working wavelength is flat. When the gold film thickness, cladding air hole diameter and air hole spacing are 15 nm, 1.228 μm and 1.5 μm respectively, the beam splitting length and extinction ratio of the polarization beam splitter are 47.26 μm and −151.43 dB respectively. Because the polarization beam splitter has extremely short beam splitting length and high extinction ratio, it has great value in the field of large-capacity integrated optics and optical communication systems. [ABSTRACT FROM AUTHOR]

Abstract This proposed structure depicts Photonic crystal fiber (PCF) including hexagonal-core for liquid sensitivity. The pretending result shows that the suggested H-PCF obtains the higher level of relative sensitivity using Finite-element-Method (FEM). At wavelength 1330 nm for liquid Ethanol (n = 1.354) having the high relative sensitivity of 76.78%; low confinement loss of 6.94 × 10−12 dB/m and the effective area of 7.04 μm2 are achieved under the Water (H 2 O), Ethanol (C 2 H 5 OH) and Benzyne analytes (C 6 H 5 -X, X = H, OH, CH 3). [ABSTRACT FROM AUTHOR]

Abstract We propose a class of photonic crystal fiber called as defective core photonic crystal fiber which can fulfill the self-similar condition for pulse compression in a relatively simple means, without the necessity for a complex approach of changing the size of air holes in the cladding. The proposed model obeys exponential decrease (increase) in dispersion (nonlinearity) along the fiber length and hence compresses the pulse under self-similar technique. We also study the effect of system parameters such as initial dispersion, nonlinearity and chirping in the self-similar compression and compared with adiabatic compression. Using extended nonlinear Schrödinger equation, we have taken into account the effect of quintic nonlinearity on the pulse compression. In the proposed configuration, the quintic nonlinearity shows only a weaker effect in the compression as compared to the cubic nonlinearity. In the present system, we show that the self-similar technique is superior with high degree of compression than the adiabatic route of compressing the pulse. The effect of fiber loss is also taken into account and the critical fiber loss coefficient for compression is estimated. [ABSTRACT FROM AUTHOR]

An innovative idea for a photonic crystal fiber-based 2 × 1 power beam combiner is presented. This research introduces an optical multiplexer (MUX) that supports wavelength multiplexing at 1.46 and 1.48 µm using a photonic crystal fiber topology. The multiplexer is a component that combines the specific wavelengths into the group of wavelengths in a network. This paper aims to create a new design structure for an optical Multiplexer based on photonic crystal fibers while optimizing the geometrical parameters and the multiplexer device and illustrating how a PCF structure could combine several optical signals into a group of signals in a single fiber. High-performance waveguides known as photonic crystal fibers (PCF) are constructed from a microstructured combination of substances with varying refractive indices. The PCF Mux design relies on appropriate PCF structure improvements and the replacement of specific air-hole sections with pure silica to manage the light coupling between the cores over the PCF axis; in comparison to traditional fiber, they have a shorter coupling length between close core and more design flexibility. [ABSTRACT FROM AUTHOR]

Optical fiber sensing technology develops rapidly and is widely used. In order to design a SPR sensor with better performance and easy production, a new type D-MOF sensor with low loss, high sensitivity and simple structure is proposed. The full vector finite element method (FEM) was used to optimize the structure parameters by using the multi-physics analysis software COMSOL, and the performance of the structure was systematically analyzed. The sensor operational wavelength spans the visible and infrared range (430 nm to 7200 nm). The refractive index detection range of 1.00–1.42, the maximum wavelength sensitivity and the optimal resolution are 60,000 nm/RIU and 1.67 × 10−6 RIU−1, respectively, and the maximum limiting loss peak is 64.99 dB/cm. In addition, MOF-SPR sensors have large tolerance and low sensitivity of structural parameters in actual manufacturing. It has great application potential in biosensing and other fields. [ABSTRACT FROM AUTHOR]

An optical fiber sensor based on combined anti-resonant reflecting (ARR) mechanism is experimentally demonstrated for simultaneous measurement of temperature and curvature. The sensor head consists of a section of liquid infiltrated simplified hollow core photonic crystal fiber (PCF) spliced to a section of silica capillary. Two types of ARR mechanisms are involved in the sensor structure: the double-layer ARR guidance in the infiltrated PCF, and the single-layer ARR guidance in the silica capillary, which result in two sets of ARR fringes in the transmission spectrum. Due to the difference in the guiding mechanism and waveguide components, the two ARR fringes exhibit different responses to temperature and curvature. By measuring the wavelength shift of the double-layer ARR fringe and the intensity variation of the single-layer ARR fringe, temperature and curvature can be determined simultaneously. [ABSTRACT FROM AUTHOR]

We found that an acoustically-induced perturbation can support a different type of quasi-phase matching for nonlinear frequency conversions in gas-filled hollow-core photonic crystal fibers. A gas pressure grating, a periodic spatial modulation of gas pressure, which is reversibly constructed by the acoustically-induced perturbation, compensates a nonzero phase mismatch and enhances the nonlinear optical process. The field amplitude oscillates about the averaged field amplitude which lineally grows with distance. While group velocity walk-off is suppressed by manipulating the gas pressure inside the fiber, a nonzero wavevector mismatch is inevitable, which can be compensated by the acoustically-induced perturbation. The frequency conversion is switchable by turning on/off the acoustically-induced perturbation. We exemplarily consider third-harmonic generation in gas-filled hollow-core photonic crystal fibers, however the conception of acoustically-induced quasi-phase matching is applicable to other kinds of nonlinear optical processes in gas-filled structures such including four-wave mixing and sum frequency generation and it would provide a new route for nonlinear optics and acoustooptics. [ABSTRACT FROM AUTHOR]

Optical sensing based on photonic crystal fiber (PCF) is attracting interests. Currently, PCF sensing suffered from the insensitivity with the changes of environmental surroundings with low refractive index. A D -shape PCF supporting plasmonic resonances based on gold nanowires is designed to demonstrated the sensitivity optical sensing in the refractive index range from 1.00 to 1.30. The finite element method is performed to optimize the device parameters, including the diameter of the large and tiny air holes, the size of the gold nanowire, and the space between the air holes. Utilizing plasmon-induced confined electrical around gold nanowires, the predicted device performance in spectral and amplitude sensitivities are up to 19,400 nm/RIU and 5.15 × 10−6 RIU, respectively. It is believed that the designed sensor can promote the development of applications in biological and pharmaceutical. [ABSTRACT FROM AUTHOR]

The simple structure of single-mode fibers as a sensing platform circumvents the technical bottlenecks associated with manufacturing difficulties. Meanwhile, compared to photonic crystal fibers, they have lower manufacturing costs and can achieve similar performance to other types of fibers, providing greater possibilities for mass production. The V-groove in the SMF destroys the original symmetry of the fiber and renders the core mode energy leak controllable, consequently enhancing the sensitivity and confinement loss (CL) intensity of the core mode as well as the resolution. The composite nanolayer (gold gas-sensitive film) combines the advantages of both the materials and mutual gain to strengthen the detection ability and continuously outputs high-quality free electrons to promote mode coupling. A dual-resonant-peak single-mode fiber (SMF) surface plasmon resonance (SPR) gas sensor with a V-groove is designed for the sensitive detection of methane and analyzed by the full-vector finite element method (FEM). By optimizing the structural parameters and polarization states, the SPR sensor can be operated in the concentration range between 0 % and 3.5 %, which can be spread across two transmission bands simultaneously with the maximum wavelength sensitivities being 12 nm/% and 8 nm/% and the corresponding resolution being 0.0083 % and 0.013 %, respectively. The tolerance of the structural parameters of the sensor is below 0.88 nm/μm to make manufacturing easier compared to conventional products. This sensor has good prospects and application potential in areas such as gas leakage diagnostics and environmental safety. [ABSTRACT FROM AUTHOR]

Abstract We proposed a new type of photonic crystal fiber (PCF) using two nano-scale elliptical air holes in the core region to control the property of birefringence and reduce the performance of nonlinearity simultaneously. Benefiting from the slot effect induced sub-wavelength mode confinement, the nonlinear coefficients of quasi-TE mode and quasi-TM mode at 1.55 μm are as low as 0.0143 W−1 m−1 and 0.02 W−1 m−1, respectively. More importantly, ultrahigh birefringence of 0.0293 is obtained at the wavelength of 1.55 μm thanks to the asymmetry of the fiber design. Owing to these excellent optical characteristics, the proposed dual-slot silica PCF will have great potential for high-speed telecom applications. [ABSTRACT FROM AUTHOR]

Abstract A polarization beam splitter (PBS) based on a novel liquid-filled dual-core photonic crystal fiber (DC-PCF) is proposed. The effects of parameters of DC-PCF on performances of the PBS are investigated by beam propagation method (BPM). The numerical results demonstrate that the PBS possesses ultra-short length of 99 μm and high extinction ratio (ER) of −33.8 dB at the wavelength of 1.55 μm. Meanwhile, an ER better than -10 dB is achieved a bandwidth of 32 nm. [ABSTRACT FROM AUTHOR]