| 1. |
- Abeywickrama, Sandu, et al.
(author)
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Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings
- 2016
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 381, s. 327-335
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Journal article (peer-reviewed)abstract
- Core network survivability affects the reliability performance of telecommunication networks and remains one of the most important network design considerations. This paper critically examines the benefits arising from utilizing dual-homing in the optical access networks to provide resource-efficient protection against link and node failures in the optical core segment. Four novel, heuristic-based RWA algorithms that provide dedicated path protection in networks with dual-homing are proposed and studied. These algorithms protect against different failure scenarios (i.e. single link or node failures) and are implemented with different optimization objectives (i.e., minimization of wavelength usage and path length). Results obtained through simulations and comparison with baseline architectures indicate that exploiting dual-homed architecture in the access segment can bring significant improvements in terms of core network resource usage, connection availability, and power consumption.
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| 2. |
- Chen, R., et al.
(author)
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A low cost surface plasmon resonance biosensor using a laser line generator
- 2015
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 349, s. 83-88
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Journal article (peer-reviewed)abstract
- Due to the instrument designed by using a common surface plasmon resonance biosensor is extremely expensive, we established a portable and cost-effective surface plasmon resonance biosensing system. It is mainly composed of laser line generator, P-polarizer, customized prism, microfluidic cell, and line Charge Coupled Device (CCD) array. Microprocessor PIC24FJ128GA006 with embedded A/D converter, communication interface circuit and photoelectric signal amplifier circuit are used to obtain the weak signals from the biosensing system. Moreover, the line CCD module is checked and optimized on the number of pixels, pixels dimension, output amplifier and the timing diagram. The micro-flow cell is made of stainless steel with a high thermal conductivity, and the microprocessor based Proportional-Integral-Derivative (PID) temperature-controlled algorithm was designed to keep the constant temperature (25 °C) of the sample solutions. Correspondingly, the data algorithms designed especially to this biosensing system including amplitude-limiting filtering algorithm, data normalization and curve plotting were programmed efficiently. To validate the performance of the biosensor, ethanol solution samples at the concentrations of 5%, 7.5%, 10%, 12.5% and 15% in volumetric fractions were used, respectively. The fitting equation ΔRU=-752987.265+570237.348×RI with the R-Square of 0.97344 was established by delta response units (ΔRUs) to refractive indexes (RI). The maximum relative standard deviation (RSD) of 4.8% was obtained.
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| 3. |
- Gong, Y., et al.
(author)
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Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks
- 2018
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 426, s. 151-157
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Journal article (peer-reviewed)abstract
- This paper proposes a crosstalk-aware passive optical interconnect architecture based on multiple arrayed waveguide gratings (AWGs). With two-stage cascaded AWGs, it can realize the communications not only within but also among the clusters for large-scale datacenters. To overcome serious crosstalk in multiple-AWG based optical interconnects, crosstalk suppression schemes are proposed. Proof-of-concept experiments are carried out to verify the necessity and feasibility of the proposed crosstalk suppression schemes for multiple-AWG based optical interconnects.
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| 4. |
- Hong, Yuanyuan, et al.
(author)
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Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation
- 2017
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 383, s. 478-484
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Journal article (peer-reviewed)abstract
- In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.
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| 5. |
- Ivanov, M., et al.
(author)
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Controlled spin of a nonbirefringent droplet trapped in an optical vortex beam
- 2018
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In: Optics Communications. - : Elsevier BV. - 0030-4018. ; 427, s. 152-157
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Journal article (peer-reviewed)abstract
- The spin part of the angular momentum of light can cause a birefringent particle to spin around its axis, while having no effect on a nonbirefringent particle. The orbital part of light's angular momentum, on the other hand, can cause both birefringent and nonbirefringent particles to orbit around the axis of a light beam. In this paper, we demonstrate that nonbirefringent particles can also be made to spin around their axis when trapped in an optical vortex beam. The rotation of the particle depends on the ratio of the size of the particle and the diameter of the laser beam in which the particle is trapped. It can therefore be controlled by varying the position of the particle with respect to the focal point of the laser beam. The rotational frequency can also be controlled by changing the polarization state of the beam, since spin-orbit coupling affects the total angular momentum experienced by the trapped particle. The motion of the trapped particle is detected by a photodiode and a high-speed camera. Most microparticles found in nature are nonbirefringent, and the method presented in this paper will therefore open up new applications for optically induced rotations.
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| 6. |
- Karras, C., et al.
(author)
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Successful optimization of reconstruction parameters in structured illumination microscopy – A practical guide
- 2019
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In: Optics Communications. - : Elsevier BV. - 0030-4018. ; 436, s. 69-75
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Journal article (peer-reviewed)abstract
- The impact of the different reconstruction parameters in super-resolution structured illumination microscopy (SIM) on image artifacts is carefully analyzed. These parameters comprise the Wiener filter parameter, an apodization function, zero-frequency suppression and modifications of the optical transfer function. A detailed investigation of the reconstructed image spectrum is concluded to be suitable for identifying artifacts. For this purpose, two samples, an artificial test slide and a more realistic biological system, were used to characterize the artifact classes and their correlation with the image spectra as well as the reconstruction parameters. In addition, a guideline for efficient parameter optimization is suggested and the implementation of the parameters in selected up-to-date processing packages (proprietary and open-source) is depicted. © 2018 The Authors
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| 7. |
- Li, Jingwei, et al.
(author)
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A portable confocal hyperspectral microscope without any scan or tube lens and its application in fluorescence and Raman spectral imaging
- 2017
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 392, s. 1-6
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Journal article (peer-reviewed)abstract
- In this study, a portable confocal hyperspectral microscope is developed. In traditional confocal laser scanning microscopes, scan lens and tube lens are utilized to achieve a conjugate relationship between the galvanometer and the back focal plane of the objective, in order to achieve a better resolution. However, these lenses make it difficult to scale down the volume of the system. In our portable confocal hyperspectral microscope (PCHM), the objective is placed directly next to the galvomirror. Thus, scan lens and tube lens are not included in our system and the size of this system is greatly reduced. Furthermore, the resolution is also acceptable in many biomedical and food-safety applications. Through reducing the optical length of the system, the signal detection efficiency is enhanced. This is conducive to realizing both the fluorescence and Raman hyperspectral imaging. With a multimode fiber as a pinhole, an improved image contrast is also achieved. Fluorescent spectral images for HeLa cells/fingers and Raman spectral images of kumquat pericarp are present. The spectral resolution and spatial resolutions are about 0.4 nm and 2.19 mu m, respectively. These results demonstrate that this portable hyperspectral microscope can be used in in-vivo fluorescence imaging and in situ Raman spectral imaging.
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| 8. |
- Lin, Rui, et al.
(author)
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Palm-shaped spectrum generation for dual-band millimeter wave and baseband signals over fiber
- 2016
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 367, s. 137-143
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Journal article (peer-reviewed)abstract
- In order to offer abundant available bandwidth for radio access networks satisfying future 5G requirements on capacity, this paper proposes a simple and cost-effective palm-shaped spectrum generation scheme that can be used for high capacity radio over fiber (RoF) system. The proposed scheme can simultaneously generate an optical carrier used for upstream and two bands of millimeter wave (MMW) that are capable of carrying different downstream data. The experiment results show that the proposed palm-shaped spectrum generation scheme outperforms optical frequency comb (OFC) based multi-band MMW generation in terms of upstream transmission performance. Furthermore, simulation is carried out with different dual-band MMW configurations to verify the feasibility of using the proposed spectrum generation scheme in the RoF system.
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| 9. |
- Lin, Rui, et al.
(author)
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Scalability analysis methodology for passive optical interconnects in data center networks using PAM
- 2017
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 403, s. 283-289
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Journal article (peer-reviewed)abstract
- A framework is developed for modeling the fundamental impairments in optical datacenter interconnects, i.e., the power loss and the receiver noises. This framework makes it possible, to analyze the trade-offs between data rates, modulation order, and number of ports that can be supported in optical interconnect architectures, while guaranteeing that the required signal-to-noise ratios are satisfied. To the best of our knowledge, this important assessment methodology is not yet available. As a case study, the trade-offs are investigated for three coupler-based top-of-rack interconnect architectures, which suffer from serious insertion loss. The results show that using single-port transceivers with 10 GHz bandwidth, avalanche photodiode detectors, and quadratical pulse amplitude modulation, more than 500 ports can be supported.
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| 10. |
- Lu, Yang, et al.
(author)
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Orthogonal modulation application to achieve flexible migration and colorless ONUs for next generation PON
- 2017
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 403, s. 252-256
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Journal article (peer-reviewed)abstract
- Flexible migration that reuse the deployed infrastructure and colorless ONUs which avoid inventory problem are two major challenges of next-generation passive optical network (NGPON). In this paper, flexible migration is achieved by the coexistence of legacy PON and NGPON and colorless ONUs is achieved by upstream remodulation. Orthogonal modulation methods such as DPSK, PolSK and WSK are applied for NGPON downstream signal to ensure the constant amplitude. The amplitude-constant NGPON downstream signal induces low crosstalk to the coexisting legacy PON signal and the remodulated upstream signal. The experimental demonstration shows error free transmission and verifies the feasibility of the proposed scheme.
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