| 1. |
- Abeywickrama, Sandu, et al.
(författare)
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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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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 381, s. 327-335
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Tidskriftsartikel (refereegranskat)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.
(författare)
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A low cost surface plasmon resonance biosensor using a laser line generator
- 2015
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 349, s. 83-88
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks
- 2018
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 426, s. 151-157
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation
- 2017
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 383, s. 478-484
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Tidskriftsartikel (refereegranskat)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. |
- Li, Jingwei, et al.
(författare)
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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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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 392, s. 1-6
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Lin, Rui, et al.
(författare)
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Palm-shaped spectrum generation for dual-band millimeter wave and baseband signals over fiber
- 2016
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 367, s. 137-143
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Lin, Rui, et al.
(författare)
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Scalability analysis methodology for passive optical interconnects in data center networks using PAM
- 2017
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 403, s. 283-289
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Lu, Yang, et al.
(författare)
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Orthogonal modulation application to achieve flexible migration and colorless ONUs for next generation PON
- 2017
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 403, s. 252-256
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Rosa, Adriana, et al.
(författare)
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Statistical analysis of blocking probability and fragmentation based on Markov modeling of elastic spectrum allocation on fiber link
- 2015
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 354, s. 362-373
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Tidskriftsartikel (refereegranskat)abstract
- In Elastic Optical Network (EON), spectrum fragmentation refers to the existence of non-aligned, small-sized blocks of free subcarrier slots in the optical spectrum. Several metrics have been proposed in order to quantify a level of spectrum fragmentation. Approximation methods might be used for estimating average blocking probability and some fragmentation measures, but are so far unable to accurately evaluate the influence of different sizes of:connection requests and do not allow in-depth investigation of blocking events and their relation to fragmentation. The analytical study of the effect of fragmentation on requests' blocking probability is still under explored In this work, we introduce new definitions for blocking that differentiate between the reasons for the blocking events. We developed a framework based on Markov modeling to calculate steady-state probabilities for the different blocking events and to analyze fragmentation related problems in elastic optical links under dynamic traffic conditions. This framework can also be used for evaluation of different definitions of fragmentation in terms of their relation to the blocking probability. We investigate how different allocation request sizes contribute to fragmentation and blocking probability. Moreover, we show to which extend blocking events, due to insufficient amount of available resources, become inevitable and, compared to the amount of blocking events due to fragmented spectrum, we draw conclusions on the possible gains one cart achieve by system defragmentation. We also show how efficient spectrum allocation policies really are in reducing the part of fragmentation that in particular leads to actual blocking events. Simulation experiments are carried out showing good match with our analytical results for blocking probability in a small scale scenario. Simulated blocking probabilities for the different blocking events are provided for a larger scale elastic optical link.
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| 10. |
- Sun, Fei, et al.
(författare)
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Subwavelength focusing by optical surface transformation
- 2018
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Ingår i: Optics Communications. - : ELSEVIER SCIENCE BV. - 0030-4018 .- 1873-0310. ; 427, s. 139-146
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel beam-compression device to achieve sub-wavelength focusing (SF) by optical surface transformation (a new theoretical branch derived from transformation optics). When a Gaussian beam is incident on the input surface of our device, we can obtain a sub-wavelength focused spot at the output surface of the compression device. The focused mode can still propagate to the far-field and keep very good directivity as incident Gaussian beam. The size of the sub-wavelength beam can be tuned by changing the size of the output surface. We only need one kind of homogeneous anisotropic medium, the optic-null medium (ONM), to realize the proposed beam-compression device. After some simplifications, we design a layered structure of two isotropic homogeneous media to realize the device. Numerical simulations verify the performance of our beam-compression device.
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| 11. |
- Villafani Caballero, Diego, et al.
(författare)
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SCM/WDM-PON with in-service baseband embedded OTDR monitoring
- 2015
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 356, s. 250-255
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Tidskriftsartikel (refereegranskat)abstract
- Subcarrier Multiplexing and Wavelength Division Multiplexing Passive Optical Network (SCM/WDM-PON) is a promising solution to support Radio over Fiber (RoF) for the convergence of optical and wireless access networks. In this paper, we propose a novel SCM/WDM-PON system with in-service baseband monitoring, which uses an optical carrier to supervise the fiber infrastructure and several subcarriers to transmit data signals simultaneously. The performance of the proposed system is investigated where an embedded baseband Optical Time Domain Reflectometry (OTDR) signal is applied for fiber fault monitoring. The results have verified the feasibility of the proposed system and shown that with proper configuration the in-service baseband monitoring signals have negligible impact on data transmission.
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| 12. |
- Xu, Tianhua, et al.
(författare)
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Analytical BER performance in differential n-PSK coherent transmission system influenced by equalization enhanced phase noise
- 2015
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 334, s. 222-227
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Tidskriftsartikel (refereegranskat)abstract
- Long haul high speed optical transmission systems are significantly distorted by the interplay between the electronic chromatic dispersion (CD) equalization and the local oscillator (LO) laser phase noise, which leads to an effect of equalization enhanced phase noise (EEPN). The EEPN degrades the performance of optical communication systems severely with the increment of fiber dispersion. LO laser linewidth, symbol rare, and modulation format. In this paper, we present an analytical model for evaluating the performance of bit-error-rate (BER) versus signal-to-noise ratio (SNR) in the n-level phase shift keying (n-PSK) coherent transmission system employing differential carrier phase estimation (CPE), where the influence of EEPN is considered. Theoretical results based on this model have been investigated for the differential quadrature phase shift keying (DQPSK). the differential 8-PSK (D8PSK), and the differential 16-PSK (D16PSK) coherent transmission systems. The influence of EEPN on the BER performance in term of the fiber dispersion, the LO phase noise, the symbol rate, and the modulation format are analyzed in detail. The BER behaviors based on this analytical model achieve a good agreement with previously reported BER floors influenced by EEPN. Further simulations have also been carried out in the differential CPE considering EEPN. The results indicate that this analytical model can give an accurate prediction for the DQPSK system, and a leading-order approximation for the D8PSK and the D16PSK systems.
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| 13. |
- Xu, Tianhua, et al.
(författare)
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Field trial over 820km installed SSMF its potential Terabit/s super channel application with up to 57.5-Gbaud DP-QPSK transmission
- 2015
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 353, s. 133-138
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the result of a field trial of 56-Gbaud (224-Gbit/s) and 57.5-Gbaud (230-Gbit/s) dual-polarization quadrature phase shift keying (DP-QPSK) coherent optical transmission over 820 km installed standard single mode fiber (SSMF). Offline digital signal processing (DSP) was applied for signal recovery and bit-error-rate (BER) counting in our field trial experiments, and BER performance well below the 7% overhead hard-decision forward error correction (FEC) error-free threshold (4.5×10−3) at 231-1 pseudo random bit sequence (PRBS) pattern length has been achieved, with the best achievable BERs of 2×10−4 (56-Gbaud) and 3×10−4 (57.5-Gbaud), respectively. In parallel a 1.15-Tbit/s (5×230-Gbit/s) quasi-Nyquist spaced wavelength division multiplexing (WDM) superchannel transmission over the same 820 km optical field link (FL) was also investigated through numerical simulations based on the same 57.5-Gbaud DP-QPSK signal using 1% roll-off Nyquist pulse shaping with 60-GHz channel spacing, and the results indicate that the BER performance well below the 7% overhead hard-decision FEC error-free threshold (4.5×10−3) for the 1.15-Tbit/s DP-QPSK superchannel transmission can be achieved.
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| 14. |
- Ivanov, M., et al.
(författare)
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Controlled spin of a nonbirefringent droplet trapped in an optical vortex beam
- 2018
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 427, s. 152-157
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Tidskriftsartikel (refereegranskat)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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| 15. |
- Karras, C., et al.
(författare)
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Successful optimization of reconstruction parameters in structured illumination microscopy – A practical guide
- 2019
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 436, s. 69-75
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Tidskriftsartikel (refereegranskat)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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| 16. |
- Thomas, Cyrille, et al.
(författare)
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Coherence of a near diffraction limited undulator synchrotron radiation source
- 2016
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 359, s. 171-176
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental measurements of the coherence of an undulator synchrotron radiation source near to the diffraction limit condition. These measurements have been done following two objectives. The first one is to verify a fundamental point of the theory of synchrotron radiation. To our knowledge, since it has been re-written by Geloni et al. [1], no experimental verification to validate the theory has been performed. Our measurement proves the theory to be valid for the case of a near diffraction limited undulator source. The other objective is to measure the coherence of the synchrotron radiation on the 105 beamline of Diamond, in front of the last focusing element of the beamline. This knowledge can be used to predict the focusing performance of the beamline by means of Fourier Optics. (C) 2015 The Authors. Published by Elsevier B.V.
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| 17. |
- Villafani Caballero, Diego Rodrigo, 1989, et al.
(författare)
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Embedded time-multiplexed AMCC and OTDR signals for analog radio over fiber links
- 2019
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 452, s. 195-199
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally demonstrate an optical transmitter with embedded Auxiliary Management and Control Channel (AMCC) and in-service Optical Time Domain Reflectometer (OTDR) for Long Term Evolution-Advanced (LTE-A) data transmission in mobile fronthaul section of radio access networks. The concept is tested on a direct modulation analog radio over fiber system. The OTDR and AMCC signals are time-multiplexed without interfering with each other or affecting data transmission. The coexistence of the three functionalities is achieved through proper modulation index distribution across the AMCC/OTDR and LTE-A data signals.
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