Showing papers on "Photonic-crystal fiber published in 2019"

Formation of optical supramolecular structures in a fibre laser by tailoring long-range soliton interactions

Abstract: Self-assembly of fundamental elements through weak, long-range interactions plays a central role in both supramolecular DNA assembly and bottom-up synthesis of nanostructures. Optical solitons, analogous in many ways to particles, arise from the balance between nonlinearity and dispersion and have been studied in numerous optical systems. Although both short- and long-range interactions between optical solitons have attracted extensive interest for decades, stable soliton supramolecules, with multiple aspects of complexity and flexibility, have thus far escaped experimental observation due to the absence of techniques for enhancing and controlling the long-range inter-soliton forces. Here we report that long-range soliton interactions originating from optoacoustic effects and dispersive-wave radiations can be precisely tailored in a fibre laser cavity, enabling self-assembly of large numbers of optical solitons into highly-ordered supramolecular structures. We demonstrate several features of such optical structures, highlighting their potential applications in optical information storage and ultrafast laser-field manipulation. Optical solitons have been studied in a variety of systems for their unique properties. Here, the authors report on optically observed solitonic supramolecules, made up of large-scale structures of many solitons interacting within a fiber cavity, and study their fundamental characteristics.

Design of D-shaped elliptical core photonic crystal fiber for blood plasma cell sensing application

Abstract: In this research, the proposed design presents the compact sensing performances while infiltrating the blood fluid in the central hole of the D-shaped elliptical dual-core photonic crystal fiber (PCF) configuration. The properties such as index difference, coupling length, and transmission spectrum pertains the sensing property of the blood plasma cell. The proposed sensor can detect plasma by finite element method (FEM) which can be utilized to detect the variation of plasmon of light using plasma materials.

Machine learning approach for computing optical properties of a photonic crystal fiber

Abstract: Photonic crystal fibers (PCFs) are the specialized optical waveguides that led to many interesting applications ranging from nonlinear optical signal processing to high-power fiber amplifiers. In this paper, machine learning techniques are used to compute various optical properties including effective index, effective mode area, dispersion and confinement loss for a solid-core PCF. These machine learning algorithms based on artificial neural networks are able to make accurate predictions of above-mentioned optical properties for usual parameter space of wavelength ranging from 0.5-1.8 µm, pitch from 0.8-2.0 µm, diameter by pitch from 0.6-0.9 and number of rings as 4 or 5 in a silica solid-core PCF. We demonstrate the use of simple and fast-training feed-forward artificial neural networks that predicts the output for unknown device parameters faster than conventional numerical simulation techniques. Computation runtimes required with neural networks (for training and testing) and Lumerical MODE solutions are also compared.

Hollow-Core Fiber Technology: The Rising of “Gas Photonics”

Abstract: Since their inception, about 20 years ago, hollow-core photonic crystal fiber and its gas-filled form are now establishing themselves both as a platform in advancing our knowledge on how light is confined and guided in microstructured dielectric optical waveguides, and a remarkable enabler in a large and diverse range of fields. The latter spans from nonlinear and coherent optics, atom optics and laser metrology, quantum information to high optical field physics and plasma physics. Here, we give a historical account of the major seminal works, we review the physics principles underlying the different optical guidance mechanisms that have emerged and how they have been used as design tools to set the current state-of-the-art in the transmission performance of such fibers. In a second part of this review, we give a nonexhaustive, yet representative, list of the different applications where gas-filled hollow-core photonic crystal fiber played a transformative role, and how the achieved results are leading to the emergence of a new field, which could be coined “Gas photonics”. We particularly stress on the synergetic interplay between glass, gas, and light in founding this new fiber science and technology.

A Hi-Bi Ultra-Sensitive Surface Plasmon Resonance Fiber Sensor

Abstract: In this paper, a simple, miniature, and highly sensitive photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed. The target analyte and the plasmonic material are at the outer surface of the fiber making practical applications feasible. A 30-nm gold (Au) layer supports surface plasmons. A thin titanium dioxide (TiO 2 ) layer is used to assist adhesion of Au on the glass fiber. The fiber cross section is formed purely by circular-shaped holes simplifying the preform manufacturing process. A high-birefringence (hi-bi) fiber is obtained by means of an array of air holes at the center of the fiber. A finite element method (FEM) is employed to analyze the surface plasmon properties of the proposed PCF-SPR sensor. By optimizing the geometric parameters, a maximum wavelength sensitivity (WS) of 25 000 nm/RIU and an amplitude sensitivity (AS) of 1411 RIU -1 for a dielectric refractive index (RI) range of 1.33-1.38 are obtained. Moreover, an estimated maximum resolution of 4 × 10 -6 and a figure of merit (FOM) of 502 are obtained that ensures high detection accuracy of small refractive index (RI) changes. Owing to its sensitivity and simple architecture, the proposed sensor has potential application in a range of sensing application, including biosensing.

Recent advances in plasmonic sensor-based fiber optic probes for biological applications

Abstract: The survey focuses on the most significant contributions in the field of fiber optic plasmonic sensors (FOPS) in recent years. FOPSs are plasmonic sensor-based fiber optic probes that use an optical field to measure the biological agents. Owing to their high sensitivity, high resolution, and low cost, FOPS turn out to be potential alternatives to conventional biological fiber optic sensors. FOPS use optical transduction mechanisms to enhance sensitivity and resolution. The optical transduction mechanisms of FOPS with different geometrical structures and the photonic properties of the geometries are discussed in detail. The studies of optical properties with a combination of suitable materials for testing the biosamples allow for diagnosing diseases in the medical field.

Prospects of Photonic Crystal Fiber as Physical Sensor: An Overview.

Abstract: Photonic crystal fiber sensors have potential application in environmental monitoring, industry, biomedicine, food preservation, and many more. These sensors work based on advanced and flexible phototonic crystal fiber (PCF) structures, controlled light propagation for the measurement of amplitude, phase, polarization and wavelength of spectrum, and PCF-incorporated interferometry techniques. In this article various PCF-based physical sensors are summarized with the advancement of time based on reported works. Some physical PCF sensors are discussed based on solid core as well as hollow core structures, dual core fibers, liquid infiltrated structures, metal coated fibers, grating incorporated fibers. With the advancement of sensing technology the possibilities of temperature, pressure, strain, twist, curvature, electromagnetic field, and refractive index sensing are discussed. Also, limitations as well as possible solutions and future hopes are outlined.

Femtosecond Mamyshev oscillator with 10-MW-level peak power

Abstract: Ultrafast fiber lasers exhibit high broadband gain per pass, superior thermo-optical properties, and excellent beam quality, making them very suitable for practical use. For simplicity and efficiency, advanced mode-locked oscillator designs which can compete with the amplifier systems are always favorable. Here, we demonstrate a high-peak-power Mamyshev oscillator based on single-polarization, large-mode-area photonic crystal fibers. Using properly arranged filters, the fiber oscillator directly emits pulses with 9 W average power at 8 MHz repetition rate, corresponding to a single-pulse energy exceeding 1 μJ. The pulses are dechirped to 41 fs outside the cavity, leading to a record oscillator peak power as high as 13 MW. With such unprecedented performance, the proposed single-stage oscillator should be very attractive for various applications.

Tri‐core photonic crystal fiber based refractive index dual sensor for salinity and temperature detection

Abstract: This article discusses the tri-core photonic crystal microstructure fiber for the process of simultaneous sensing for salinity and temperature of water substances. This kind of microstructure is preferred in many sensing application to scale the detection process in micrometer range. In this novel sensor, the sensitivity is calculated through coupling mechanism by tracking wavelength shift of various concentrations of salinity and temperature using finite element method. The sensible samples are in liquid and are infiltrated into the framed hollow cavity. Based on the coupling principle between silica substrate and the analyte material, the sense of the salt as well as temperature is obtained. Finally, it is noted that sensitivity of the salt level in water as 5404.9 nm/RIU for x polarization direction and 5674 nm/RIU for y polarization direction have been calculated with the temperature sensitivity of 4 nm/ C in the same water substances.

Microchannel-based plasmonic refractive index sensor for low refractive index detection

Abstract: A microchannel incorporated photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor for detection of low refractive index (RI) at near-infrared wavelength is presented in this paper. To attain a simple and practically feasible mechanism, plasmonic material gold (Au) and sensing medium are placed outside the fiber. A thin layer of TiO2 is employed as an adhesive layer to strongly attach the Au with the silica glass. In the sensing range of 1.22 to 1.37, maximum sensitivities of 51,000 nm/RIU (RI unit) and 1872 RIU−1 are obtained with resolutions of 1.96×10−6 and 9.09×10−6 RIUs using wavelength and amplitude interrogation methods, respectively. To the best of the authors’ knowledge, the obtained maximum wavelength sensitivity and resolution are the highest among reported PCF-based SPR sensors to date. The sensor also exhibits a maximum figure of merit of 566. Therefore, the proposed sensor would be an excellent candidate for a wide range of RI detection with higher accuracy for applications such as pharmaceutical inspection and leakage monitoring, bio-sensing, and other low RI analytes.

Recent Advances in Brillouin Optical Time Domain Reflectometry

Abstract: In the past two decades Brillouin-based sensors have emerged as a newly-developed optical fiber sensing technology for distributed temperature and strain measurements. Among these, the Brillouin optical time domain reflectometer (BOTDR) has attracted more and more research attention, because of its exclusive advantages, including single-end access, simple system architecture, easy implementation and widespread field applications. It is realized mainly by injecting optical pulses into the fiber and detecting the Brillouin frequency shift (BFS), which is linearly related to the change of ambient temperature and axial strain of the sensing fiber. In this paper, the authors provide a review of new progress on performance improvement and applications of BOTDR in the last decade. Firstly, the recent advances in improving the performance of BOTDRs are summarized, such as spatial resolution, signal-to-noise ratio and measurement accuracy, measurement speed, cross sensitivity and other properties. Moreover, novel-type optical fibers bring new characteristics to optic fiber sensors, hence we introduce the different Brillouin sensing features of special fibers, mainly covering the plastic optical fiber, photonic crystal fiber, few-mode fiber and other special fibers. Additionally, we present a brief overview of BOTDR application scenarios in many industrial fields and intelligent perception, including structural health monitoring of large-range infrastructure, geological disaster prewarning and other applications. To conclude, we discuss several challenges and prospects in the future development of BOTDRs.

Mathematical Model Analysis of Dispersion and Loss in Photonic Crystal Fibers

Abstract: This study has deeply investigated the basic equations analysis of dispersion and loss in photonic crystal fibers (PCF) within the operating wavelengths of 850, 1,300, and 1,550 nm. The confinement loss, effective refractive index, and effective cross-section area of PCF are also studied. The variations of total dispersion and losses against hole diameter and distance between holes variations in PCF are clarified. Confinement loss, effective refractive index, and effective cross-section area variations for PCF are sketches with the variations of the operating wavelength.

Numerical analysis of circularly polarized modes in coreless photonic crystal fiber

Abstract: In this paper, the coreless photonic crystal fiber (CO-PCF) is investigated using finite element. The absence of core in the PCF structure is achieved by applying the permanent twist on its cladding boundary and hence the light propagation path tends to be circularly polarized. The other modes can also be exerted other than the fundamental modes is known as cladding filled modes or super modes.

Design and Analysis of Surface-Plasmon-Resonance-Based Photonic Quasi-Crystal Fiber Biosensor for High-Refractive-Index Liquid Analytes

Abstract: We propose a sixfold photonic quasi-crystal fiber with a trapezoidal analyte channel based on surface plasmon resonance for the detection of high-refractive-index (RI) liquid analytes and numerically analyze its sensing performance for different liquid analyte refractive indices and heights using the finite-element method. In contrast to the common D-shaped structure photonic crystal fiber, we design a trapezoidal analyte channel to investigate the role of the sample liquid height within the channel and discussed the feasibility of the fabrication process. We find that with various liquid analyte heights ratios of 20%, 25%, 30%, and 50% of the maximum channel height, the proposed biosensor exhibits linear sensing performance with a maximum RI sensitivity of 4400, 6100, 8000, and 17000 nm/RIU, respectively, for analytes RI range of 1.44–1.57, 1.41–1.51, 1.40–1.49, and 1.40–1.44. This sensor is suitable to detect various high RI chemicals, biochemicals, and organic chemical samples. Owing to its simple structure of the proposed biosensor with promising linear sensing performance, we envisage that this biosensor could turn out to be a versatile and competitive instrument for the detection of high-RI liquid analytes.

Photonic crystal fiber metalens

Abstract: Optical fiber is a well-established efficient way to guide and manipulate light and allowing high bandwidth optical transmission for long distance communication with low attenuation. Although a dielectric optical waveguide is efficient for transmitting light, its functionality is limited by the dielectric properties of the materials of core and cladding.The light coming out from optical fiber is typically diverging, and the numerical aperture is determined by the refractive index of the fiber materials. Thus, the light intensity decreases significantly upon exiting the fiber. The use of metasurfaces provides the opportunity to tailor light properties for advanced light manipulation and to develop novel optical applications that are flat. By producing a specific phase profile using spatially-varied nano-antenna elements, metasurfaces can control the wavefront of the transmitted, reflected, and scattered light, and enable novel ultrathin optical components such as flat lenses. Here, we report an ultrathin optical metalens cascaded on the facet of optical fiber that enables light focusing in the telecommunication regime. In-fiber metalenses with focal lengths of 28 and 40 um and maximum efficiency of ~16.4% at a wavelength of 1550 nm are demonstrated. The integration of an ultrathin metalens and optical fiber will open the path to revolutionary in-fiber optical devices for practical applications in optical imaging, sensing, and fiber laser.

Different Photonic Crystal Fibers Configurations with the Key Solutions for the Optimization of Data Rates Transmission

Abstract: The study has outlined various photonic crystal fibers (PCFs) configurations for the key solution to the optimization of data rates transmission. The proposed fibers that are namely octagonal photonic crystal fiber (OPCF), hexagonal photonic crystal fiber (HPCF), and elliptical photonic crystal fiber (E-PCF) are used in the system. The dispersion parameter coefficient, pulse broadening variations, and data rates transmission are examined for proposed fibers under the same fiber lengths and number of quantization level with using pulse code modulation (PCM). The system performance is enhanced with OPCF with reducing dispersion factor, pulse broadening effects and consequently increasing data rates transmission.

Highly Sensitive Dual-Core PCF Based Plasmonic Refractive Index Sensor for Low Refractive Index Detection

Abstract: A highly sensitive surface plasmon resonance (SPR) sensor on a dual-core photonic crystal fiber (PCF) for low refractive index (RI) detection is presented in this paper. Plasmonic material silver (Ag) is deposited outside of the fiber structure to detect changes of the surrounding medium's refractive index. To prevent oxidation a thin layer of titanium dioxide (TiO 2 ) is employed on top of the silver. The sensor shows maximum wavelength sensitivity and amplitude sensitivity of 116,000 nm/RIU and 2452 RIU -1 with corresponding resolutions (R) of 8.62 × 10 -7 and 5.55 × 10 -6 RIU, respectively. A thorough study of the relevant literature yielded that these attained sensitivities in both interrogation methods are the highest among reported PCF-SPR sensors to date. In addition, the sensor possesses a very high figure of merit of 2320 in the sensing range of 1.29 to 1.39. Therefore, it would be a suitable candidate for pharmaceutical inspection, organic chemical sensing, and biosensing and other analytes detection.

Highly sensitive open-channels based plasmonic biosensor in visible to near-infrared wavelength

Abstract: In this paper, we numerically demonstrate a low-cost plasmonic refractive index sensor using two-sided open-channels that can operate in both visible and near-infrared region. Widely used finite element method (FEM) software is employed to characterize the sensing properties. A thin coating of gold layer is used inside the open channels of the photonic crystal fiber (PCF) to create the plasmons. It is reported that the highest wavelength sensitivity of 5000 nm/RIU with a sensor resolution of 2.0 × 10−5 RIU can be achieved at an analyte refractive of 1.38. Besides, it is also achievable to have the highest amplitude sensitivity of 396 RIU−1. The proposed sensor shows excellent linear characteristics with the highest figure of merit (FOM) of 47 RIU−1 between a refractive index of 1.33 and 1.39. Due to structural simplicity and improved sensitivity, the proposed plasmonic sensor is highly applicable in biological and biochemical analyte detections.

Mid-infrared flattened supercontinuum generation in all-normal dispersion tellurium chalcogenide fiber

Abstract: We have prepared a well-structured tellurium chalcogenide (ChG) fiber with a specialized double cladding structure by an improved extrusion method, and experimentally demonstrated an ultra-flat mid-infrared (MIR) supercontinuum (SC) generation in such a fiber. The step-index fiber had an optical loss of <1 dB/m in a range from 7.4 to 9.7 μm with a minimum loss of 0.69 dB/m at 7.87 μm. Simulation showed that an all-normal dispersion profile can be realized in this double cladding tellurium fiber. An ultra-flat MIR SC spectrum (~3.2-12.1μm at −10 dB, ~2-14 μm at −30 dB) was generated from a 22-cm long fiber pumped with a femtosecond laser at 5 μm (~150 fs, 1 kHz). Then the degree of coherence was calculated out based on a simulation, showing that a high coherent MIR SC (from 2.9 to 13.1 μm) can be generated in this double-cladding tellurium fiber.

Numerical Analysis of Optical Properties Using Octagonal Shaped Photonic Crystal Fiber

Abstract: In this paper, we propose a design of octagonal photonic crystal fiber with relevant parameters such as effective mode index, propagation constant, second-order dispersion and field distribution of fundamental mode (LP01). The measured parameters can be applied for generating supercontinuum, and also this model is used especially for generating vortex modes and OAM modes in space division multiplexing (SDM) applications. Highly negative dispersion is achieved at −800 ps/nm.km at wavelength of 1.1 μm, and second-order dispersion profile leads to study about the nonlinearity as well as broadband spectrum of the proposed model.

Dual-Core Photonic Crystal Fiber Plasmonic Refractive Index Sensor: A Numerical Analysis

Abstract: A numerical analysis on dual core photonic crystal fiber (DC-PCF) based surface plasmon resonance (SPR) refractive index sensor is presented. The guiding parameters and required sensing performances are examined with finite element method (FEM) based software under MATLAB environment. According to simulation, it is warrant that the proposed refractive index sensor offers the maximum amplitude sensitivity of 554.9 refractive index unit (RIU−1) and 636.5 RIU−1 with the maximum wavelength sensitivity of 5800 nm/RIU and 11 500 nm/RIU, and the sensor resolution of 1.72 × 10−5 RIU and 8.7 × 10−6 RIU, at analyte refractive index (RI) of 1.40 for x- and y-polarized modes, respectively. As the sensing performance in different wavelength ranges is quite high, the proposed sensor can be used in simultaneous detection for different wavelength ranges. Therefore, the proposed device is of a suitable platform for detecting biological, chemical, biochemical, and organic chemical analytes.

Ring-core photonic crystal fiber for propagation of OAM modes.

Abstract: We propose and fabricate a novel ring-core photonic crystal fiber made of a circular ring core surrounded by a cladding constituted of air holes organized in a first circular ring surrounded by hexagonal ones. The fiber efficiently supports four different groups of orbital angular momentum (OAM) modes. The effective indices of spin-orbit aligned and spin-orbit anti-aligned modes in the same OAM modes group are separated by at least 2.13×10−3 at 1550 nm. The realized fiber is expected to be a good platform for applications involving OAM modes.

Highly sensitive refractive index sensor based on D-shaped PCF with gold-graphene layers on the polished surface

Abstract: D-shaped photonic crystal fiber (PCF) sensor in the infrared spectrum is proposed to detect the analytes/liquids of different refractive indices (RIs) ranging from 1.32 to 1.40. To observe the effect of surface plasmon a thin layer of gold was deposited on the D-shaped PCF. Then a flake of graphene was deposited on the layer of gold. Graphene improves the detection capability of PCF sensors because of its excellent molecule adsorption property. Its large surface area and rich π conjugation make it a suitable dielectric layer for sensing. The proposed sensor is designed and numerically analyzed using finite element method. The thickness of the gold, graphene layer and the diameter of the two large air holes of PCF are varied to study its effect on the sensing characteristics of the proposed SPR-based PCF sensor. It is observed that the sensitivity improved to 33,500 nm RIU−1 with effective RI resolution of 2.98 × 10-5 RIU which makes the device more competitive among various plasmonic sensors.

High power, single-frequency, monolithic fiber amplifier for the next generation of gravitational wave detectors

Abstract: Low noise, high power single-frequency lasers and amplifiers are key components of interferometric gravitational wave detectors. One way to increase the detector sensitivity is to increase the power injected into the interferometers. We developed a fiber amplifier engineering prototype with a pump power limited output power of 200 W at 1064 nm. No signs of stimulated Brillouin scattering are observed at 200 W. At the maximum output power the polarization extinction ratio is above 19 dB and the fractional power in the fundamental transverse mode (TEM 00) was measured to be 94.8 %. In addition, measurements of the frequency noise, relative power noise, and relative pointing noise were performed and demonstrate excellent low noise properties over the entire output power slope. In the context of single-frequency fiber amplifiers, the measured relative pointing noise below 100 Hz and the higher order mode content is, to the best of our knowledge, at 200 W the lowest ever measured. A long-term test of more than 695 h demonstrated stable operation without beam quality degradation. It is also the longest single-frequency fiber amplifier operation at 200 W ever reported.

Exposed-core localized surface plasmon resonance biosensor

Abstract: We propose and numerically characterize an exposed-core photonic crystal fiber for biosensing applications. Surface plasmons are excited within gold (Au) strips, and titanium dioxide is employed to support adhesion of Au with glass. In consideration of ease of fabrication, only four air holes are used to simplify the sensor structure. Simulation results show an improved wavelength and amplitude sensitivity of 34,000 nm/RIU and 1170 RIU−1, respectively, that comes with a low confinement loss of 0.79 dB/cm. Results also indicate a low full width at half-maximum that contributes to high figure of merit of 310.

A dual-channel surface plasmon resonance biosensor based on a photonic crystal fiber for multianalyte sensing

Abstract: A dual-channel photonic crystal fiber sensor based on the surface plasmon resonance effect is proposed and numerically investigated. The proposed design consists of two concentric channels, with an external coating of gold (Au) on solid silica. Multiple analytes are analyzed based on two different modes operating in the first and second channel, and wavelength sensitivity of 1000 nm/RIU and 3750 nm/RIU respectively. The proposed sensor design could be used in various sensing applications, e.g., for chemicals, biochemicals, organics, and other lower-index liquids having refractive index in the range of 1.30–1.40.

Mid IR hollow core fiber gas laser emitting at 4.6 μm

Abstract: Emission at 4.6 μm was observed from an N2O filled hollow core fiber laser. 8-ns pump pulses at 1.517 μm excited a vibrational overtone resulting in lasing on an R and P branch fundamental transition from the upper pump state. At optimum gas pressure of 80 Torr, photon conversion efficiency of 9% and slope efficiency of 3% were observed from a mirrorless laser. The laser threshold occurred at absorbed pump energy of 150 nJ in a 45-cm long fiber with 85 μm core diameter. The observed dependence of the laser output on gas pressure was shown to be a result of line broadening and relaxation rates.