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AIP Conference Proceedings [AIP Publishing SECOND INTERNATIONAL CONFERENCE ON MATERIAL SCIENCE, SMART STRUCTURES AND APPLICATIONS: ICMSS-2019 - Erode, India (21–22 November 2019)] SECOND INTERNATIONAL CONFERENCE ON MATERIAL SCIENCE, SMART STRUCTURES AND APPLICATIONS: ICMSS-2019 - Adopted octagonal photonic crystal fiber for analyte liquids sensing
摘要： In this paper, octagonal-photonic crystal fiber (O-PCF) has been proposed for studying liquid types for sensing applications. The propagation properties for the proposed O-PCF were studied numerically by utilizing full-vector finite element method (FV-FEM ) using COM SOL M ultiphysics version 5.1. The confinement loss, the relative sensitivity, and the nonlinearity coefficient can be controlled by changing the factors related with the geometry such as the cladding in a range of wavelength, air hole diameter, and the core pitch. The proposed O-PCF is realized with three rings from the air hole in the cladding and two circular rings in the core region. Numerical simulation of the proposed structure is achieving the highest sensitivity by increasing the diameter of the air hole the cladding, while the pitch remains constant. At the same time, the confinement losses have distinguishable decrease with an increase in diameter as well as an increase in the number of rings within the cladding layer. In addition, the effective area and the nonlinear coefficient each of them is affected with every hole of the diameter and with the type of the chemical material used. The proposed model shows that the fiber is of a high efficiency not only in the sensing application, but also being distinguishable with the nonlinear optical application.
关键词： chemical sensor,nonlinearity coefficient,O-PCF,Sensitivity,confinement loss
更新于2025-09-12 10:27:22
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Optical microfiber-based ultrafast fiber lasers
摘要： Optical microfibers drawn from conventional fibers have attracted considerable interests and have found many novel applications. Here, we review recent advances in ultrafast fiber lasers based on optical microfibers. Starting with characteristics and fabrication of optical microfibers, which are closely related to ultrafast fiber lasers, we show that characteristics of large portion of evanescent field, tailorable dispersion, high optical nonlinearity, very low optical loss and full compatibility with conventional fibers are greatly beneficial to novel ultrafast fiber lasers. We then highlight recent works on ultrafast fiber lasers based on optical microfibers in terms of fast saturable absorbers made from optical microfiber-supported nanomaterials, dispersion management and high optical nonlinearity, as well as some other novel ultrafast fiber lasers. Finally, we briefly discuss future opportunities for optical microfiber-based ultrafast fiber lasers, such as high-order dispersion management, nonlinearity management and applications for sensing and measurement.
关键词： Dispersion management,Saturable absorbers,Ultrafast fiber lasers,Optical microfibers,Optical nonlinearity
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Engineering the Enhancement of Nonlinear Optical Properties of 2D Structures
摘要： The challenge of nonlinear optics stems from the negligible interaction among electromagnetic waves in free space, motivating substantial efforts to identify materials with sufficient anharmonic response as to enable optical nonlinearities at low light powers. On the nanoscale, near-field intensity enhancement through optical resonators has been widely explored to design active photonic devices operating on subwavelength scales. Further interest in nanoscale nonlinear optics has arisen with the isolation of graphene and other atomically-thin materials that combine a large electro-optic response with strong intrinsic nonlinearities. Despite their large nonlinear optical susceptibilities, the response of 2D materials is limited by their inherently small volumes. Optical resonances provide a promising way for circumventing this limitation, as they can enhance the driving electric field, thus boosting the effective nonlinear response. In the present work we introduce a figure-of-merit (FoM) that quantifies the enhancement of the nonlinear optical response that can be achieved in 2D materials by means of resonant cavities. As concrete examples, we apply our FoM to explore the extrinsic near-field enhancement provided by (1) localized nanoparticle plasmons acting on a 2D material; (2) the extrinsic enhancement in a 2D material produced by Mie-like resonances in dielectric nanoparticles; (3) the intrinsic enhancement of optical nonlinearity in a dielectric nanoparticle by its supported Mie resonances; (4) the effect of lattice resonances on the nonlinear response for a periodic 2D array of dielectric nanodisks. We focus in particular on the enhancement in second- and third-harmonic generation, as well as the Kerr nonlinearity, quantifying the yield of these nonlinear processes in each of the systems. Our FoM provides an efficient tool to explore the dependence of the nonlinear response enhancement by optical resonances on the size-to-wavelength ratio, composition, and geometry, thus facilitating the design of structures with optimal nonlinear yields.
关键词： Kerr nonlinearity,optical resonances,harmonic generation,nonlinear optics,2D materials,figure-of-merit
更新于2025-09-12 10:27:22
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Nonlinear Rectangular Photonic Crystal Fiber (PCF) for Optical Communication Exclusively Super Continuum Generation
摘要： A rectangular PCF structure in BK7 glass with inner and outer cladding is used to investigate effective mode field area, high nonlinear coefficient, and confinement loss and dispersion property using 2D FDTD technique. The PCF structure is purposed to design with pitches and air hole diameter in a periodic array fashion. The different properties of PCF structure like mode field area, nonlinear coefficient, confinement loss and dispersion are to be analyzed. The variation is investigated with change of different parameters like ?1, d1/?1, ?2/?1, and d1/d2 for a wide range of wavelength. The proposed rectangular PCF structure has slightly more nonlinear coefficient (γ=36.98 W-1km-1) than the highly nonlinear silica photonic crystal fiber (γ=35 W-1 km-1) at a wavelength of 1.55 μm with almost same mode field area (Aeff ~ 2.8 μm2). This result seems to be important in super-continuum generation and nonlinear fiber optics.
关键词： Kerr nonlinearity,FDTD method,Super-continuum generation,PCF
更新于2025-09-12 10:27:22
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Real-time characterization of spectral instabilities in a mode-locked fibre laser exhibiting soliton-similariton dynamics
摘要： the study of dissipative solitons in mode-locked lasers reveals a rich landscape of interaction dynamics resulting from the interplay of nonlinearity, dispersion and dissipation. Here, we characterize a range of instabilities in a dissipative soliton fibre laser in a regime where both conventional soliton and similariton propagation play significant roles in the intracavity pulse shaping. Specifically, we use the Dispersive fourier transform technique to perform real-time spectral measurements of buildup dynamics from noise to the generation of stable single pulses, phase evolution dynamics of bound state “similariton molecules”, and several examples of intermittent instability and explosion dynamics. These results show that the instabilities previously seen in other classes of passively mode-locked fibre lasers are also observed in the presence of strong nonlinear attraction of similariton evolution in an optical fibre amplifier.
关键词： explosion dynamics,Dispersive fourier transform,similariton molecules,intermittent instability,dispersion,nonlinearity,mode-locked lasers,dissipative solitons,dissipation
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Control of Terahertz Nonlinearity in Graphene by Gating
摘要： We study the dependence of the terahertz (THz) nonlinearity of graphene and its temporal dynamics on the free carrier concentration by THz-pump/THz-probe spectroscopy of a gated graphene at room temperature. The strong THz nonlinearity is attributed to electron heating by the driving THz field and shows a drastic dependence on the background electron concentration, demonstrating a wide-range tunability of the THz nonlinearity of graphene.
关键词： Gating,Electron heating,Graphene,Nonlinearity,Terahertz
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Soliton Combs Generation Due to Parametric up and Down Conversion in a Microring Resonator with Quadratic Nonlinearity
摘要： Frequency comb generation in microring resonators has been intensively studied in the last decade. Frequency combs have applications in precision measurements and optical signal processing. The discrete nature of whispering gallery modes allows microresonators to be natural candidates for frequency comb generation. However, dispersive effects avoid homogeneous spacing between frequency comb lines and for that reason they need to be balanced. Thus, it is essential to generate optical solitons which are, by definition, a result of a balance between the dispersive and nonlinear properties of a resonator.
关键词： microring resonator,quadratic nonlinearity,soliton combs,frequency comb generation
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Spatial Akhmediev Breathers in Slab Waveguides
摘要： The analytical breather-solutions of the Nonlinear Schr¨odinger Equation (NLS) have been intensively studied and veri?ed experimentally in the time-space system of optical pulse propagation in ?bers. In space-space systems, i.e. in optical beam propagation breathers in ultra-fast nonlinear media have not been observed due to the breather’s in?nite background and a resulting extremely large power. In a lithium niobate slab waveguide with two second-harmonic (SH) resonances the resulting quasi-cubic cascaded quadratic nonlinearity provided together with the intrinsic cubic susceptibility enough nonlinearity for breather excitation at experimentally reachable powers. We could characterize the ?rst ultra-fast spatial-spatial optical breathers in a 5-cm-long titanium in diffused lithium niobate slab waveguide at power levels down to tens of kW. The guided fundamental wave (FW) TM0 ?lm mode at l=1.32mm is phase-matched for type-I SH generation to TE0 and TE1 SH modes at temperatures near 295 and 344C. With temperature tuning the phase-mismatch and the two effective cascaded nonlinearities were adjusted. For breather observation, we aimed for a large phase-mismatch with low SH levels such that the cascaded nonlinearity is quasi-cubic and the propagation is well approximated by the NLS and its breather solutions. A frequency-doubled Nd:YAG-pumped OPA with CW-seeding delivered 5-ps long pulses with up to 200kW peak power in the waveguide. With a cylindrical telescope the beam was transformed into a very wide elliptical beam to approximate the breather background. The beam was end-?re coupled into the FW TM0 mode. A variable few% of the beam were separated and coupled with a tilt and good overlap to the main beam into the waveguide to produce a spatial modulation of the input with adjustable period and modulation depth. A beam width of 1.5mm was large enough in the compromise between available beam power and in?nite beam width. A beam with a transverse modulation with periods between 130 to 300mm approximates a constant background with modulation well enough to trigger modulation instability that develops eventually into the breather. The FW and the SH output of the waveguide were imaged into cameras. By changing the power the breather moves along the waveguide and the whole breather can be sampled at the waveguide end during a power scan. Each sample is normalized to its total power. An example is shown in Fig.1. Fig.1(left) Measured breather, scanned at the waveguide output dependent on power. (right) Simulation of the measurement. The in?uence of deviations from ideal theory and real world conditions like ?nite beam width, damping, non-uniform phase-mismatch, pulsed input, and cascading instead of an exact cubic nonlinearity was investigated in simulations describing the experiment very well (see example in Fig.1). The new platform is very versatile. A wide parameter space of different nonlinearity, varying transverse breather period and input modulation depth was investigated. Higher-order breathers were observed (see the grow-ing maxima between the main peaks in Fig.1). The drastic temperature-dependent reduction of the power level for breather formation due to cascading was observed. The expected speci?c details of quadratic breathers like a SH following the FW was documented. The spatial breather spectra showed the expected triangular shape.
关键词： modulation instability,lithium niobate slab waveguide,Nonlinear Schr¨odinger Equation,cascaded quadratic nonlinearity,optical breathers
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Controlling the Temporal Trajectory of Solitons in Silver Nanoparticle Doped Fibre
摘要： Silver nanoparticle doped photonic crystal fibres (SNPCF) exhibit negative Kerr nonlinearity over certain wavelength ranges [1]. At some specific wavelength, the nonlinearity vanishes representing a zero-nonlinearity (ZN) point, allowing for new propagation dynamics of solitons due to controllable interaction of dispersion and nonlinearity [2]. Here we show that the presence of a ZN point significantly influences the temporal trajectory of a soliton during the process of supercontinuum (SC) generation. The input pulse launched in the anomalous dispersion domain but with negative nonlinearity, close to zero dispersion wavelength (ZDW), generates bright solitons exhibiting complex acceleration, deceleration, and shaping behaviour, due to Raman effect, nonlinear dispersion and the four-wave mixing interaction processes. We study the variations of dynamics for different ZN points demonstrating the efficient control of soliton trajectories.
关键词： supercontinuum generation,solitons,nonlinear dispersion,zero-nonlinearity point,silver nanoparticle doped fibre
更新于2025-09-11 14:15:04
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Super Gaussian pulse generation in a passively mode-locked fiber laser
摘要： The generation of self-similar super Gaussian-like pulses from a passively mode-locked fiber laser is numerically demonstrated. The laser cavity utilizes a long period fiber grating as a pulse-shaping element. The model is based on the normalized complex Ginzburg-Landau equation and the nonlinear coupled mode equations of the grating. The numerical results show stable super Gaussian pulses with a linear frequency chirp, a 1.5 ps pulse duration and 2 nJ energy. The generated pulses are scalable and exhibits no bifurcation or instability as the gain is increased.
关键词： Mode-locked fiber lasers,Ginzburg-Landau equation,Kerr nonlinearity,Self-similar pulses,Numerical methods
更新于2025-09-11 14:15:04