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27 results on '"Guan, Yefeng"'

5. Dual-Channel Supply Chain Coordination Considering Green and Service Inputs.

Author

Guan, Yefeng, Wan, Chao, and Wang, Wei

Abstract

The rise of the green economy and the dual-channel model has led to consumer preferences for a model that is both green and service-based. At the same time, customer service expectations have led to greater uncertainties in corporate decision-making. However, many research gaps remain in terms of how green and service-based models work together in a dual-channel supply chain to influence operational decisions and achieve efficiency improvements. Therefore, while considering customer expectations, this study adopts Stackelberg game theory to construct a dual-channel supply chain analysis that considers green and service inputs and analyzes the optimal decisions of manufacturers and retailers. The results show that when the costs of green inputs are low, this increases the greenness and prices of green products while also stimulating the retailer to improve service levels and common product prices. When the retailer's service costs are low, this promotes higher service levels and product prices but inhibits product greenness and green product prices in the online channel. In addition, centralized decision-making is associated with higher product greenness, which is beneficial from an environmental perspective. Numerical analysis further reveals that profit-sharing contracts can be effective in achieving supply chain coordination. These findings have reference significance for the coexistence and interaction of green and service-based factors in dual-channel supply chains, as well as provide a reference value for the impact of customer service expectations on supply chain-related decision-making. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Noninvasive nonlinear imaging through strongly-scattering turbid layers

Author

Katz, Ori, Small, Eran, Guan, Yefeng, and Silberberg, Yaron

Subjects
Physics - Optics
Abstract

Diffraction-limited imaging through complex scattering media is a long sought after goal with important applications in biomedical research. In recent years, high resolution wavefront-shaping has emerged as a powerful approach to generate a sharp focus through highly scattering, visually opaque samples. However, it requires a localized feedback signal from the target point of interest, which necessitates an invasive procedure in all-optical techniques. Here, we show that by exploiting optical nonlinearities, a diffraction-limited focus can be formed inside or through a complex sample, even when the feedback signal is not localized. We prove our approach theoretically and numerically, and experimentally demonstrate it with a two-photon fluorescence signal through highly scattering biological samples. We use the formed focus to perform two-photon microscopy through highly scattering, visually opaque layers.

Published
2014
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7. Polarization control of multiply-scattered light through random media by wavefront shaping

Author

Guan, Yefeng, Katz, Ori, Small, Eran, Zhou, Jianying, and Silberberg, Yaron

Subjects
Physics - Optics
Abstract

We show that the polarization state of coherent light propagating through an optically thick multiple-scattering medium, can be controlled by wavefront shaping, i.e. by controlling only the spatial phase of the incoming field with a spatial light modulator. Any polarization state of light at any spatial position behind the scattering medium can be attained with this technique. Thus, transforming the random medium to an arbitrary optical polarization component becomes possible.

Published
2012
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8. Spectral control of broadband light through random media by wavefront shaping

Author

Small, Eran, Katz, Ori, Guan, Yefeng, and Silberberg, Yaron

Subjects
Physics - Optics
Abstract

A random medium can serve as a controllable arbitrary spectral filter with spectral resolution determined by the inverse of the interaction time of the light in the medium. We use wavefront shaping to implement an arbitrary spectral response at a particular point in the scattered field. We experimentally demonstrate this technique by selecting either a narrow band or dual bands with a width of 5.5nm each.

Published
2012
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14. Optimizing lightwave transmission through a nano-tip

Author

Xie, Xiangsheng, Chen, Yongzhu, Zhang, Peiqing, Guan, Yefeng, Zhou, Jianying, Wong, Kam Sing, Yan, Li, Kurizki, Gershon, Xie, Xiangsheng, Chen, Yongzhu, Zhang, Peiqing, Guan, Yefeng, Zhou, Jianying, Wong, Kam Sing, Yan, Li, and Kurizki, Gershon

Abstract

Optical microscopy with spatial resolution below the diffraction limit is at present attracting extensive attentions. Further advancement of the near-field scanning optical microscopy (NSOM), a practical super-resolution microscopy, is mainly limited by the low transmission of optical power through the nano-meter apex. This work shows that lightwave can be efficiently delivered to a sub-100 nm apex inside a tapered metallic guiding structure. The enhanced light delivery, about 5-fold, is made possible with an adaptive optimization of the transmission via a spatial light phase-modulator. Numerical simulation shows the mechanism for the efficient light delivery to be the selective excitation of predominantly the lowest-order transverse component of standing wavevector with proper input wavefront modulation, hence favoring the transmission of lightwave in the longitudinal direction. The demonstration of such efficient focusing, to about full-width at half-maximum of a quarter wavelength, has a direct and immediate application in the improvement of the existing NSOMs. Copyright 2011 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License. [doi:10.1063/1.3598477]

Published
2011

15. Coherent Beam Combining with Second-Harmonic Generation Optimized with Adaptive Phase Control

Author

Guan, Yefeng, Zhang, Peiqing, Xie, Xiangsheng, Zhou, Jianying, Wong, Kam Sing, Guan, Yefeng, Zhang, Peiqing, Xie, Xiangsheng, Zhou, Jianying, and Wong, Kam Sing

Abstract

A theoretical and experimental study of phase-controlled beam combining based on noncollinear frequency doubling is described. Optimized second-harmonic power and improved output intensity distribution are simultaneously achieved by a closed-loop phase control system via an adaptive algorithm. It is shown that the profile of the combined beam at the second-harmonic with 12 noncollinear frequency inputs can be shaped to a near-fundamental Gaussian mode, with a power enhancement of more than two orders of magnitude, compared to the second-harmonic signal generated with a single beam.

Published
2011

17. Phase controlled beam combining with nonlinear frequency conversion

Author

Zhang, Peiqing, Guan, Yefeng, Xie, Xiangsheng, Zhou, Jianying, Yan, Li, Wong, Kam Sing, Zhang, Peiqing, Guan, Yefeng, Xie, Xiangsheng, Zhou, Jianying, Yan, Li, and Wong, Kam Sing

Abstract

A phase controlled beam combining via nonlinear optical conversion is proposed and demonstrated. This process involves the combining of the fields at the second harmonic frequency generated by non-collinear input fields. The arrangement of the excitation configuration allows the generated second-harmonic light waves to propagate collinearly, with phases coherently correlated. The manipulation of the conversion efficiency is then possible with the phase control of the input fields. The combined second-harmonic fields are shown to be conveniently and robustly variable from zero to a maximum value that greatly exceeds the second-harmonic field generated by a single laser beam. By using a self-adaptive control algorithm, it is possible to optimize the output without prior knowledge on each beamlet property. Either the second-harmonic output beam profile or the total second-harmonic output power can be optimized with the control algorithm. (C) 2010 Optical Society of America

Published
2010

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