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Coupled Mode Demonstration of Slow-Light Plasmonic Sensor Based on Metasurface at Near-Infrared Region
摘要： In this paper, we theoretically and numerically reported a dual plasmon-induced transparency and the relevant sensing property in a multi-cross metasurface by the coupled mode analysis. A phase coupling model was established to characterize the optical response of this plasmonic sensor. It was found that the transparency windows were sensitive to the resonance mode of each metal strip, which was well demonstrated by the theoretical model. Both the sensing property and the slow light in this structure were discussed. A high figure of merit of 223 and sensitivity of 850 nm/RIU were achieved. In addition, the 1170-nm near-infrared light can be slowed down by nearly two order of magnitude with group delay of 0.45 ps in this sensor. These results may provide guidance for light-matter interaction-enhanced slow-light sensor and integrated optical circuit design.
关键词： Plasmon-induced transparency,Plasmonic sensor,Metasurface,Slow light,Coupled mode theory
更新于2025-09-23 15:21:01
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Higha??Responsivity Mida??Infrared Black Phosphorus Slow Light Waveguide Photodetector
摘要： Black phosphorus (BP) offers unique opportunities for mid-infrared (MIR) waveguide photodetectors due to its narrow direct bandgap and layered lattice structure. Further miniaturization of the photodetector will improve operation speed, signal-to-noise ratio, and internal quantum efficiency. However, it is challenging to maintain high responsivities in miniaturized BP waveguide photodetectors because of reduced light–matter interaction lengths. To address this issue, a method utilizing the slow light effect in photonic crystal waveguides (PhCWGs) is proposed and experimentally demonstrated. A shared-BP photonic system is proposed and utilized to fairly and precisely characterize the slow light enhancement. Close to the band edge around 3.8 μm, the responsivity is enhanced by more than tenfold in the BP photodetector on a 10 μm long PhCWG as compared with the counterpart on a subwavelength grating waveguide. At a 0.5 V bias, the BP PhCWG photodetector achieves a 11.31 A W?1 responsivity and a 0.012 nW Hz?1/2 noise equivalent power. The trap-induced photoconductive gain is validated as both the dominant photoresponse mechanism and the major limiting factor of the response speed. The BP slow light waveguide photodetector is envisioned to realize miniaturized high-performance on-chip MIR systems for widespread applications including environmental monitoring, industrial process control, and medical diagnostics.
关键词： waveguides,slow light,photodetectors,mid-infrared,black phosphorus
更新于2025-09-23 15:21:01
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Tunable quad-band transmission response, based on single-layer metamaterials
摘要： We investigated the electromagnetically induced transparency (EIT)-like effects in planar metamaterials (MMs) at microwave (GHz) frequencies. The specific MMs that were used in this study consist of cut-wire resonator/ring resonator, which achieved the dual EIT-like effects in a single-layer through the bright- and quasi-dark-mode coupling and the lattice mode coupling. In addition, by varying the distance between the two resonators, the quad-band EIT spectral response in the microwave region was obtained, and the group refractive index at the EIT-like resonance of proposed design reached up to 4,000. This study provides the design approach to the multispectral EIT-like effects and might suggest potential applications in a variety of fields, for example, low-loss slow-light device, multiple switching sensor, and other sensing devices.
关键词： microwave frequencies,slow-light device,quad-band transmission,electromagnetically induced transparency,metamaterials
更新于2025-09-23 15:21:01
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Coupled-mode-induced transparency and attenuation resulting from cross-polarization coupling
摘要： Induced transparency and attenuation effects are observed in the throughput of a single whispering-gallery microresonator due to mode coupling between two coresonant orthogonally polarized whispering-gallery modes of very different quality factors. Intracavity cross-polarization coupling, occurring when either the transverse electric (TE) mode or the transverse magnetic (TM) mode is driven, results in coupled-mode induced transparency or coupled-mode induced attenuation. Coresonance between the TE and TM modes is obtained by strain tuning, and the cross-polarization coupling is produced by polarization rotation due to optical spin-orbit interaction in a slightly asymmetric resonator. The observed behavior enables slow light and fast light, i.e., the delay or advancement of an incident resonant pulse. Experimental results representative of several different types of behavior are presented here. Induced transparency is seen to be accompanied by pulse delay, whereas induced attenuation can involve pulse advancement or delay. The results are analyzed and explained by analytical modeling and by comparison to the output of a more detailed numerical model describing these effects. Delays of up to 170 ns and advancements of up to 14 ns are found. The observed range of cross-polarization coupling strengths (probability of polarization change per round trip), namely, 10?10–10?7, is in agreement with theory.
关键词： slow light,induced transparency,whispering-gallery microresonator,cross-polarization coupling,attenuation,fast light
更新于2025-09-23 15:19:57
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The dispersion behaviors of the tripod-type four-level cylindrical quantum dot under phenomenon of electromagnetically induced transparency
摘要： In this paper, linear and 3rd-order nonlinear group velocities of the probe laser field are investigated in a tripod-type four-level cylindrical quantum dot (TTFLCQD) with parabolic potential in electromagnetically induced transparency. The control lasers at z-polarization are applied to the system and the results are investigated. Also, linear and 3rd-order nonlinear group velocities in z-polarization are compared. The effects of parameters of TTFLCQD and control lasers on linear and 3rd-order nonlinear group velocities are explored. Finally, the results are discussed. The linear and 3rd-order nonlinear group velocities are compared at z-polarization. Furthermore, the effects of parameters of TTFLCQD and control lasers on linear and 3rd-order nonlinear group velocities are explored. Finally, the results are discussed. The linear and 3rd-order nonlinear group velocities are compared at z-polarization. Furthermore, the effects of parameters of TTFLCQD and control lasers on linear and 3rd-order nonlinear group velocities are explored. Finally, the results are discussed.
关键词： Electromagnetically induced transparency,Tripod-type four-level cylindrical quantum dot,Nonlinear group velocity,Linear group velocity,Slow light
更新于2025-09-23 15:19:57
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Review on plasmon induced transparency based on metal-dielectric-metal waveguides; ??o?o? MDM ?3￠?ˉ?????-??|??-????èˉ±?ˉ?é??????????????è?°;
摘要： Plasmon induced transparency (PIT) in the transparent window provides new insights into the design of optical filters, switches and storage, and integrated optics. The slow light effect makes PIT applicable to both sensors and slow light devices. Besides, PIT can overcome the diffraction limit of light, which makes it possible to manipulate light on a half-wavelength scale and brings good news to the miniaturization of optical devices. In this paper, we first summarize the researches of PIT phenomenon based on metal-dielectric-metal (MDM) waveguide systems and analyze the physical mechanisms of PIT including bright-dark mode interactions and phase-coupling-induced transparency. Then, we review the applications of PIT in optical sensing, optical filtering, optical switching, slow light devices and optical logic devices. At last, we outline important challenges that need to be addressed, provide corresponding solutions and predict important directions for future research in this area.
关键词： slow-light effect,plasmon induced transparency (PIT),metal-dielectric-metal (MDM) waveguide,optical logic devices
更新于2025-09-23 15:19:57
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Tunable plasmon-induced transparency and slow light in terahertz chipscale semiconductor plasmonic waveguides
摘要： We numerically propose the plasmon-induced transparency (PIT) and slow light effect based on terahertz (THz) chipscale plasmonic semiconductor-insulator-semiconductor (SIS) waveguide system. Via the coupling between two stub resonators, PIT is introduced due to the destructive interference, which can be theoretically described by the transmission-line Method (TLM). Meanwhile, the strong dispersion within the transparent window will lead to the slow light effect. Via tuning the geometric parameters, the profile of PIT as well as group delay line can be arbitrarily tailored. Moreover, active control of both PIT and slow light can be realized by changing the ambient temperature. Especially, by integrating monolayer graphene into the structure, PIT and slow light can also be electrically modulated via applying voltage. This work provides geometrical, thermal and electrical approaches to manipulate THz transmission and group delay in subwavelength scale, and can find potential applications as filters, sensors, modulators and active optical delay lines in THz ultracompact circuits.
关键词： graphene,plasmon-induced transparency,slow light,terahertz,plasmonic waveguide
更新于2025-09-23 15:19:57
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INVESTIGATION ON PLASMON INDUCED TRANSPARENCY AND ITS APPLICATION IN AN MIM TYPECOMPOUND PLASMONIC WAVEGUIDE
摘要： In this paper, the investigation about a metal-insulator-metal (MIM) compound plasmonic waveguide is reported, which possesses the transmission property of plasmon induced transparency (PIT) and exhibits the potential application of refractive index sensing. The waveguide structure consists of an MIM-type bus waveguide, a horizontally placed asymmetric H-type resonator (AHR), and a circular ring resonator (CRR). The AHR is directly coupled with the bus waveguide, while the CRR is directly coupled to the AHR, but is indirectly coupled to the bus waveguide. Due to the destructive interference between two di?erent transmission paths, PIT e?ect can be observed in the transmission spectrum. The ?nite element method (FEM) is used to study the PIT e?ect in detail. The results show that the transmission characteristics can be ?exibly adjusted by changing the geometric parameters of the structure, and the proposed waveguide structure has potential application prospects in the area of temperature and refractive index sensing with higher sensitivity, better ?gure of merit, and in the area of slow light photonic devices.
关键词： plasmon induced transparency,slow light,MIM waveguide,refractive index sensing
更新于2025-09-23 15:19:57
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Second-harmonic generation from 2D photonic crystal waveguide with simultaneous near-flat dispersions at fundamental frequency and second harmonic
摘要： Photonic crystal waveguides (PCW) have shown great potential to generate second harmonic (SH), but the available schemes with cavity or defect suffer from a lack of multiple wavelengths operation and excessive phase-matching requirement. Here we propose a 2D PCW structure comprised of a modulated single line defect, which is capable of independently controlling the fundamental frequency (FF) and SH modes. Therefore, two near-flat group velocity dispersions can be achieved for these modes, and they simultaneously satisfy phase matching conditions. Based on multiply scattering method, we theoretically demonstrate that the SH resonant modes originated from the nonradiative near-flat dispersion have high quality factors (nearly 6.5 × 104 for the maximum value). And the maximum SH conversion efficiency for these resonant modes are 2 orders of magnitude higher than that of off-resonant modes. In addition, benefitting from the matching of the group velocities of the second harmonic and the fundamental, the central wavelength of SH can be modulated within wavelength range ～3nm. These results can provide potential applications in on-chip integration of photonics and quantum optics.
关键词： Photonic crystal waveguides,Nonlinear optics,Harmonic generation and mixing,Slow light
更新于2025-09-19 17:13:59
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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