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Junpeng Guo

Publications and source records attributed to Junpeng Guo.

15 recordsLinked to original sources

Dual-disentangle Framework for Diversified Sequential Recommendation

Sequential recommendation predicts user preferences over time and has achieved remarkable success. However, the growing length of user interaction sequences and the complex entanglement of evolving user interests and intentions introduce significant challenges to diversity. To address these, we propose a model-agnostic Dual-disentangle framework for Diversified Sequential Recommendation (DDSRec). The framework refines user interest and intention modeling by adopting disentangling perspectives in interaction modeling and representation learning, thereby balancing accuracy and diversity in sequential recommendations. Extensive experiments on multiple public datasets demonstrate the effectiveness and superiority of DDSRec in terms of accuracy and diversity for sequential recommendations.

cs.IR

A Literature Review on Simulation in Conversational Recommender Systems

Conversational Recommender Systems (CRSs) have garnered attention as a novel approach to delivering personalized recommendations through multi-turn dialogues. This review developed a taxonomy framework to systematically categorize relevant publications into four groups: dataset construction, algorithm design, system evaluation, and empirical studies, providing a comprehensive analysis of simulation methods in CRSs research. Our analysis reveals that simulation methods play a key role in tackling CRSs' main challenges. For example, LLM-based simulation methods have been used to create conversational recommendation data, enhance CRSs algorithms, and evaluate CRSs. Despite several challenges, such as dataset bias, the limited output flexibility of LLM-based simulations, and the gap between text semantic space and behavioral semantics, persist due to the complexity in Human-Computer Interaction (HCI) of CRSs, simulation methods hold significant potential for advancing CRS research. This review offers a thorough summary of the current research landscape in this domain and identifies promising directions for future inquiry.

cs.HC

Towards Live Video Analytics with On-Drone Deeper-yet-Compatible Compression

In this work, we present DCC(Deeper-yet-Compatible Compression), one enabling technique for real-time drone-sourced edge-assisted video analytics built on top of the existing codec. DCC tackles an important technical problem to compress streamed video from the drone to the edge without scarifying accuracy and timeliness of video analytical tasks performed at the edge. DCC is inspired by the fact that not every bit in streamed video is equally valuable to video analytics, which opens new compression room over the conventional analytics-oblivious video codec technology. We exploit drone-specific context and intermediate hints from object detection to pursue adaptive fidelity needed to retain analytical quality. We have prototyped DCC in one showcase application of vehicle detection and validated its efficiency in representative scenarios. DCC has reduced transmission volume by 9.5-fold over the baseline approach and 19-683% over the state-of-the-art with comparable detection accuracy.

cs.NI

Observation of the Modification of Quantum Statistics of Plasmonic Systems

For almost two decades, it has been believed that the quantum statistical properties of bosons are preserved in plasmonic systems. This idea has been stimulated by experimental work reporting the possibility of preserving nonclassical correlations in light-matter interactions mediated by scattering among photons and plasmons. Furthermore, it has been assumed that similar dynamics underlies the conservation of the quantum fluctuations that define the nature of light sources. Here, we demonstrate that quantum statistics are not always preserved in plasmonic systems and report the first observation of their modification. Moreover, we show that multiparticle scattering effects induced by confined optical near fields can lead to the modification of the excitation mode of plasmonic systems. These observations are validated through the quantum theory of optical coherence for single- and multi-mode plasmonic systems. Our findings constitute a new paradigm in the understanding of the quantum properties of plasmonic systems and unveil new paths to perform exquisite control of quantum multiparticle systems.

quant-ph

Experimental Observation of Strong Coupling Between an Epsilon-Near-Zero Mode in a Deep Subwavelength Nanofilm and a Gap Plasmon Mode

Strong coupling is a phenomenon which occurs when the interaction between two resonance systems is so strong that the oscillatory energy exchange between them exceeds all dissipative loss channels. Each resonance can then no longer be described individually but only as a part of the coupled, hybrid system. Here, we show that strong coupling can occur in a deep subwavelength nanofilm supporting an epsilon near zero mode which is integrated into a metal-insulator-metal gap plasmon structure. To generate an epsilon near zero mode resonance in the short-wave infrared region, an indium tin oxide nanofilm of ~lambda/100 thickness is used. A polariton splitting value of 27%, corresponding to a normalized coupling rate of 0.135, is experimentally demonstrated. Simulations indicate that much larger coupling rates, well within the ultra-strong regime where the energy exchange rate is comparable with the frequency of light, are possible.

physics.optics

Subwavelength metal grating metamaterial for polarization selective optical antireflection coating

A metamaterial structure consisting of a one-dimensional metal/air-gap subwavelength grating is investigated for optical antireflection coating on germanium substrate in the infrared regime. For incident light polarized perpendicularly to the grating lines, the metamaterial exhibits effective dielectric property and Fabry-Perot like plasmon-coupled optical resonance results in complete elimination of reflection and enhancement of transmission. It is found that the subwavelength grating metamaterial antireflection structure does not require a deep subwavelength grating period, which is advantageous for device fabrication. Maximal transmittance of 93.4% with complete elimination of reflection is seen in the mid-wave infrared range.

physics.optics

Multi-spectral near perfect metamaterial absorbers using spatially multiplexed plasmon resonance metal square structures

Near perfect infrared light absorption at multi-spectral wavelengths has been experimentally demonstrated by using multiplexed metal square plasmon resonance structures. Optical power absorption over 95% has been observed in dual-band metamaterial absorbers at two separate wavelengths and optical power absorption over 92.5% has been observed in triple-band metamaterial absorbers at three separate wavelengths. The peak absorption wavelengths are primarily determined by the sizes of the metal squares in the multiplexed structures. Electrical field distributions in the middle of the dielectric spacer layer were calculated at the peak absorption wavelengths. It is shown that strong light absorption corresponds to the local quadrupole plasmon resonance modes in the metamaterial structures.

physics.optics

Mode splitting of surface plasmon resonances in super-period metal nanohole gratings

We experimentally observed the surface plasmon resonance mode splitting in a super-period metal nanohole grating under the transverse magnetic polarization excitation. The mode splitting was observed in the zeroth order transmission and also in the first order diffracted transmission. However, the mode splitting phenomenon is more evident in the first order transmission than in the zeroth order transmission. It is explained that the mode splitting is due to the coupling between the surface plasmon resonance mode in the subwavelength period metal nanohole arrays and the resonance mode of the metal super-grating.

physics.optics

Investigation of Surface Plasmon Resonance in Super-Period Gold Nanoslit Arrays

Surface plasmon resonance in super-period metal nanoslits can be observed in the first order diffraction as well in the zeroth order transmission. In this paper, surface plasmon resonance modes in various super-period gold nanoslit arrays are investigated. It is found that the surface plasmon resonance frequencies are determined by the small period of the nanoslits in super-period nanoslits. The number of nanoslits in the unit cell super-period and the nanoslit width do not control the surface plasmon resonance frequencies. It is also found that the resonance wavelength observed in the first order diffraction reveals more accurate the real surface plasmon resonance wavelength in the metal super-period nanoslit array device.

physics.optics

Guided Surface Plasmon Mode of Semicircular Cross Section Silver Nanoridges

Tightly confined plasmon waveguide modes supported by semicircular cross section top silver nanoridges are investigated in this paper. Mode field profiles, dispersion curves, propagation distances, confinement factors, and figure-of-merits of semicircular top silver nanoridge plasmon waveguide mode are calculated for different radii of curvature at different wavelengths. It is found that semicircular top silver nanoridges support tightly confined quasi-TEM plasmon waveguide modes. Semicircular top silver nanoridge mode has longer propagation distance and higher figure-of-merit than that of the cylindrical silver nanowire of the same radius of curvature.

physics.optics

Guided Plasmon Modes of Elliptical Cross Section Silver Nanoridges

Propagating two-dimensional plasmon modes guided by elliptical cross section silver nanoridges are investigated in this paper. Mode field profiles, dispersion curves, propagation distances, and figure-of-merits of the plasmon ridge modes are calculated for various elliptical cross sections. It is found that an elliptical cross section metal nanoridge, if designed properly, can support a well-confined plasmon mode with a longer propagation distance and a higher figure-of-merit than the flat-top nanoridge plasmon waveguide of the same width. The optimal ridge waveguide cross section is obtained when the elliptical ridge top has a semicircular cross section. When the curvature of the elliptical nanoridge is large, the mode approaches the tightly confined wedge plasmon mode.

physics.optics

Guided plasmon modes of triangular and inverted triangular cross section silver nanoridges

Propagating two-dimensional plasmon modes guided along silver nanoridge waveguides with triangular and inverted triangular cross sections are investigated in this paper. Mode field profiles, dispersion curves, propagation distances, and figure-of-merits of the plasmon ridge modes are calculated for silver nanoridge waveguides with various triangular and inverted triangular waveguide cross sections. It is found that the triangular cross section nanoridge waveguide, if designed properly, can have longer propagation distance and higher figure-of-merit than the flat-top nanoridge waveguide of the same width. When the triangle height of the nanoridge is high, the mode approaches to the small angle wedge mode. An inverted triangular cross section nanoridge mode can be considered as a hybrid mode of two metal wedge plasmon modes. When inverted triangle depth increases, the propagation distance and the figure-of-merit decrease dramatically, suggesting the poorer performance when compared to the flat-top nanoridge plasmon waveguide.

physics.optics

Wideband Optical Filters with Small Gap Coupled Subwavelength Metal Structures

In this letter, we show that the bandwidth of optical band-stop filters made of subwavelength metal structures can be significantly increased by the strong plasmonic near-field coupling through the corners of the periodic metal squares. The effect of small gap coupling on the spectral bandwidth is investigated by varying the gap size between the metal squares. An equivalent transmission line model is used to fit the transmission and reflection spectra of the metal filters. The transmission line model can characterize well the metal structures with the gap size larger than the near-field decay length. However, it fails to model the transmission and reflection spectra when the gap size reaches the decay range of the near-field in the small gaps.

physics.optics

A wide-band perfect light absorber at mid-wave infrared using multiplexed metal structures

We experimentally demonstrate a wide band near perfect light absorber in the mid-wave infrared region using multiplexed plasmonic metal structures. The wide band near perfect light absorber is made of two different size gold metal squares multiplexed on a thin dielectric spacing layer on the top of a thick metal layer in each unit cell. We also fabricate regular non-multiplexed structure perfect light absorbers. The multiplexed structure IR absorber absorbs above 98% incident light over a much wider spectral band than the regular non-multiplexed structure perfect light absorbers in the mid-wave IR region.

physics.optics

Mode Properties of Flat-top Silver Nano-ridge Surface Plasmon Waveguides

We investigate surface plasmon modes supported by flat-top silver nano-ridges. We calculate the mode electromagnetic field distribution, the dispersion curve, the travel range, and the figure-of-merit of the nano-ridge mode. We find that the nano-ridge surface plasmon modes are quasi-TEM modes with longitudinal field components three orders of magnitude smaller than the transverse field components. The quasi-TEM nature of mode profiles reveals that the propagation of free electron oscillations on the top of the nano-ridge contributes mainly to the tightly confined ridge mode. We also find that as the width of the nano-ridge decreases, the ridge mode becomes more tightly confined on the ridge top. As the width of the nano-ridge increases, the nano-ridge mode approaches two decoupled right-angle wedge plasmon modes.

physics.optics