- 标题
- 摘要
- 关键词
- 实验方案
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Highly Dispersion Tailored Property of Novel Class of Multimode Surface Plasmon Resonance Biosensor Assisted by Teflon and Metamaterial Layers
摘要： In this paper, we describe a novel dispersion tailored properties of surface plasmon resonance (SPR) sensor assisted by Te?on and metamaterial layers. The dispersion property and the excitation methods of surface plasmon (SP) waves have been great signi?cance in sensor design. Most of the time, SPR sensor designed for biosensing has been dual mode and its side lobes in dispersion graph can signi?cantly reduce the sensitivity. We propose a design of as many as ?ve-mode SP sensor assisted by Te?on and metamaterial layers. A new sensing theory for exploring highly dispersion tailored properties of multilayer sensor structure is design for ef?cient biorecognition. The proposed design scheme is able to completely remove the side lobes in the dispersion graph by properly controlling the Te?on layer, thin gold ?lm, and metamaterial thickness for the case of multimode SPR sensor. To the best of our knowledge, dispersion tailored properties of multimode SP sensor assisted by Te?on and metamaterial layers together have not been explored and analyzed. The standard matrix method is applied to calculate the various performance parameters of the sensor. Experimental validation has been done with available results for a speci?c case.
关键词： matrix method,re?ectance,metamaterial,Te?on layer,Group velocity dispersion (GVD)
更新于2025-09-23 15:22:29
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Regular perturbation on the group-velocity dispersion parameter for nonlinear fibre-optical communications
摘要： Communication using the optical fibre channel can be challenging due to nonlinear effects that arise in the optical propagation. These effects represent physical processes that originate from light propagation in optical fibres. To obtain fundamental understandings of these processes, mathematical models are typically used. These models are based on approximations of the nonlinear Schr?dinger equation, the differential equation that governs the propagation in an optical fibre. All available models in the literature are restricted to certain regimes of operation. Here, we present an approximate model for the nonlinear optical fibre channel in the weak-dispersion regime, in a noiseless scenario. The approximation is obtained by applying regular perturbation theory on the group-velocity dispersion parameter of the nonlinear Schr?dinger equation. The proposed model is compared with three other models using the normalized square deviation metric and shown to be significantly more accurate for links with high nonlinearities and weak dispersion.
关键词： group-velocity dispersion,nonlinear fibre-optical communications,regular perturbation theory,nonlinear Schr?dinger equation
更新于2025-09-23 15:19:57
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Investigating the Dynamics of Intense Pulses Propagating in a Photon Crystal Optical Fiber with a Group Velocity Dispersion Gradient
摘要： The dynamics of soliton-like pulses propagating in a fiber with a group velocity dispersion gradient is studied analytically in the tunnel ionization mode and with forced Raman self-scattering. The these effects are shown to mutually compensate for each other under certain conditions, resulting in signal stabilization.
关键词： group velocity dispersion gradient,signal stabilization,soliton-like pulses,forced Raman self-scattering,tunnel ionization
更新于2025-09-19 17:13:59
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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) - Dispersion and Ridge Width Effect in Terahertz Quantum Cascade Laser Combs
摘要： We systematically investigate the laser ridge width effect on comb operation of single plasmon waveguide quantum cascade lasers emitting around 4.2 THz. The total group velocity dispersion (GVD), including gain, waveguide, and material dispersions, is numerically evaluated for 6-mm-long lasers with ridge widths varying from 100 to 200 μm. The simulation reveals that the clamped gain dispersion strongly contributes to the total GVD and the laser with a 150-μm-wide ridge shows the flattest total GVD in the lasing range between 4.05 and 4.35 THz. The optimal ridge width of 150 μm for comb operation is also experimentally verified.
关键词： group velocity dispersion,frequency comb,quantum cascade laser,ridge width,terahertz
更新于2025-09-16 10:30:52
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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) - Slow and Stopped Light in a Time-Dependent Moiré Grating
摘要： The reduction in the group velocity of a light pulse due to a resonance is termed slow light. A velocity reduction to 17 m/s was demonstrated using electromagnetically induced transparency (EIT) [1]. It was later demonstrated that light could be stopped completely [2-3]. Whilst slow light EIT experiments have been ground breaking, they require a vapour cloud cooled close to 0 K. Here we present a possible alternative using gratings and a time-dependent refractive index. Slow light can be induced by a Bragg grating by propagating a pulse with a carrier frequency close to the rejection band created by the Bragg resonance. This is accompanied by a substantial increase in group velocity dispersion (GVD) causing significant pulse broadening and limiting practical uses. A Moiré grating, which is a superposition of two grating periods has been suggested as a potential solution to reduce GVD [4]. The two grating periods produce two rejection bands separated by a transmission band. Propagating a pulse through the transmission band induces slow light, but the GVD generated by one rejection band is compensated by the other. We have developed a parametrisation for the Moiré grating periods such that they produce a transmission band centred on a given carrier frequency. Further using the parametrisation, we have derived a set of modified coupled mode equations, describing the coupling of the amplitudes A and B of the forward and backward propagating light for gratings of strength (cid:78) and with (cid:47)s the Moiré period and (cid:39)b the detuning. Our numerical simulations of a frequency-resolved version of Eq. (1) confirm that Moiré gratings produce slow light with minimal pulse broadening. The bandwidth of the rejection bands is dependent on the strength of the grating which is controlled by the grating modulation ?n. As the grating strength is increased, the rejection bands broaden reducing the transmission gap. If the grating strength is increased sufficiently the transmission band will close. Figures 1(a) and (b) show simulations of pulse propagation through a Moiré grating using finite difference time domain (FDTD) methods. The group velocity is given by the gradient of propagation distance versus time. Figure 1(a) shows propagation for a time-independent ?n. In Figure 1(b), ?n is increased by a time-dependent refractive index [5]; at 190 ps ?n is increased so that the transmission gap closes and is decreased to its original value at 440 ps, reopening the transmission gap. Closing the transmission band whilst a pulse is propagating through the grating induces stopped light. The pulse becomes trapped and remains stationary within the grating until the grating strength is reduced and the pulse can continue to propagate, analogous to results achieved in EIT [2-3]. Figure 1(c) shows how the transmission band closes as a function of the grating modulation. While the realisation of a time-dependent Moiré grating remains challenging, it presents a versatile alternative to the storage and release of light pulses in a solid-state platform, which would provide an essential element for, e.g., quantum information processing.
关键词： time-dependent refractive index,stopped light,slow light,group velocity dispersion,Moiré grating
更新于2025-09-16 10:30:52
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Use of heavily doped germanosilicate fibres with a small core diameter in stretchers of ultrashort laser pulses at a wavelength of 1.03 μm
摘要： The use of a heavily doped germanosilicate fibre with a W-profile refractive index and small core diameter in stretchers of ultrashort laser pulses with their subsequent amplification and compression in all-fibre laser systems is considered. The application of fibres of this type makes it possible to stretch, amplify, and then compress a laser pulse with minimum distortions of its initial shape and width. Due to the dispersion properties of these fibres, which allow the pulse duration to be increased significantly at a small fibre length and the third-order positive dispersion of the diffraction-grating-based output compressor to be compensated for, amplified pulses with an energy of 2 mJ and width of 250 fs, free of a picosecond pedestal, are obtained. Several types of fibres intended for the use in stretchers of ultrashort laser pulses are comparatively analysed from the point of view of their dispersion compatibility with a diffraction-grating-based output compressor.
关键词： nonlinear self-phase modulation,fibre lasers,heavily doped germanosilicate fibre,group-velocity dispersion,femtosecond lasers,amplification of ultrashort laser pulses
更新于2025-09-16 10:30:52
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[IEEE 2019 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM) - Boulder, CO, USA (2019.1.9-2019.1.12)] 2019 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM) - Frozen-Light Modes in 3-way Coupled Silicon Ridge Waveguides
摘要： Frozen-light modes supported by the stationary inflection point (SIP) within the pass band of 3-way coupled periodic silicon ridge waveguides is demonstrated. Precise tuning of the coupling between forward and backward propagating modes lead to mode degeneracy with vanishing group velocity. The unit cell is tuned to obtain the SIP on the third branch in the dispersion diagram. Subsequently, we demonstrate a finite structure with 23 unit cells to support the frozen mode at the SIP frequency. For this example, the group velocity at the SIP is 385 times slower than speed of light in vacuum. Transmission resonances of the finite structure, as well as the field distribution within the device at the SIP frequency are studied and presented.
关键词： Frozen-light modes,group velocity,dispersion engineering,3-way coupled periodic silicon ridge waveguides,stationary inflection point
更新于2025-09-16 10:30:52
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Nonlinear Fiber Optics || Group-velocity dispersion
摘要： The preceding chapter showed how the combined effects of group-velocity dispersion (GVD) and self-phase modulation (SPM) on optical pulses propagating inside a fiber can be studied by solving a pulse-propagation equation. Before considering the general case, it is instructive to study the effects of GVD alone. This chapter considers the pulse-propagation problem by treating fibers as a linear optical medium. In Section 3.1 we discuss the conditions under which the GVD effects dominate over the nonlinear effects by introducing two length scales associated with GVD and SPM. Dispersion-induced broadening of optical pulses is considered in Section 3.2 for several specific pulse shapes, including Gaussian and 'sech' pulses. The effects of initial frequency chirping are also discussed in this section. Section 3.3 is devoted to the effects of third-order dispersion on pulse broadening. An analytic theory capable of predicting dispersive broadening for pulses of arbitrary shapes is also given in this section. We discuss in Section 3.4 how the GVD can limit the performance of optical communication systems and how the technique of dispersion management can be used to combat such limitations.
关键词： dispersion management,dispersion-induced broadening,sech pulses,Group-velocity dispersion,GVD,optical pulses,third-order dispersion,SPM,Gaussian pulses,self-phase modulation,fiber propagation,frequency chirping
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Optical solitons
摘要： A fascinating manifestation of the fiber nonlinearity occurs through optical solitons, formed as a result of the interplay between the dispersive and nonlinear effects. The word soliton refers to special kinds of wave packets that can propagate undistorted over long distances. Solitons have been discovered in many branches of physics. This chapter focuses on pulse propagation inside optical fibers in the regime in which both the group-velocity dispersion (GVD) and self-phase modulation (SPM) are equally important and must be considered simultaneously. It is organized as follows. Section 5.1 considers the phenomenon of modulation instability and shows that propagation of a continuous-wave (CW) beam inside optical fibers is inherently unstable and may convert the CW beam into pulse train under appropriate conditions. The inverse-scattering method is discussed in Section 5.2 together with the soliton solutions. The properties of the fundamental and higher-order solitons are also discussed in this section. Section 5.3 is devoted to other kinds of solitons, with emphasis on dark solitons. Section 5.4 considers the effects of external perturbations on solitons. Perturbations discussed include fiber losses, amplification of solitons, and noise introduced by optical amplifiers. Higher-order nonlinear effects such as self-steepening and intrapulse Raman scattering are the focus of Sections 5.5 and 5.6.
关键词： modulation instability,optical amplifiers,dark solitons,intrapulse Raman scattering,inverse-scattering method,self-steepening,group-velocity dispersion,fiber nonlinearity,self-phase modulation,fiber losses,optical solitons
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Stimulated Raman scattering
摘要： Stimulated Raman scattering (SRS) is an important nonlinear process that can turn optical fibers into broadband Raman amplifiers and tunable Raman lasers. It can also severely limit the performance of multichannel lightwave systems by transferring energy from one channel to the neighboring channels. This chapter is devoted to a thorough study of SRS phenomenon in optical fibers. Section 8.1 presents the basic theory behind SRS with emphasis on the pump power required to reach the Raman threshold. SRS under continuous-wave (CW) and quasi-CW conditions is considered in Section 8.2, where we also discuss the performance of fiber-based Raman lasers and amplifiers. Ultrafast SRS occurring for pulses of 100-ps width or less is considered in Sections 8.3 and 8.4 for normal and anomalous group-velocity dispersion (GVD), respectively. In both cases, attention is paid to the walk-off effects together with those resulting from self-phase modulation (SPM) and cross-phase modulation (XPM). Section 8.5 focuses on the polarization effects.
关键词： Raman amplifiers,optical fibers,Stimulated Raman scattering,nonlinear processes,group-velocity dispersion,Raman lasers,polarization effects,self-phase modulation,cross-phase modulation
更新于2025-09-12 10:27:22