The Experts below are selected from a list of 186 Experts worldwide ranked by ideXlab platform
Andrew J Phillips - One of the best experts on this subject based on the ideXlab platform.
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performance evaluation of turbulence accentuated Interchannel Crosstalk for hybrid fibre and free space optical wavelength division multiplexing systems using digital pulse position modulation
Iet Optoelectronics, 2016Co-Authors: Afamefuna Maduka Mbah, John G Walker, Andrew J PhillipsAbstract:A hybrid fibre and free-space optical communication link using digital pulse-position modulation (DPPM) in a wavelength-division-multiplexing system is proposed. Such a system, which could provide a power efficient, robust and flexible solution to high-speed access networks, is a contender for a passive optical network solution and could readily be deployed in areas with restrictions in optical fibre installation, or alternatively as a disaster recovery network. Interchannel Crosstalk and atmospheric turbulence are major impairments in such a system and could combine in some cases to degrade the system. Both impairments are investigated here and the results are presented in the form of bit error probability, required optical transmission power and power penalties. Depending on the position of the interferer relative to the desired user, power penalties of about 0.2–3.0 dB for weak turbulence and above 20 dB for strong turbulence regimes are reported for bit error rate of 10−6. DPPM scheme with a coding level of 2 show about 2 dB improvements over on–off-keying scheme.
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performance evaluation of digital pulse position modulation for wavelength division multiplexing fso systems impaired by Interchannel Crosstalk
Iet Optoelectronics, 2014Co-Authors: Afamefuna Maduka Mbah, John G Walker, Andrew J PhillipsAbstract:Wavelength division multiplexing (WDM) has been proposed for fibre, intersatellite, free space and indoor optical communication systems. Digital pulse position modulation (DPPM) is a more power efficient modulation format than on-off keying (OOK) and a strong contender for the modulation of free-space systems. Although DPPM obtains this advantage in exchange for a bandwidth expansion, WDM systems using it are still potentially attractive, particularly for moderate coding levels. However, WDM systems are susceptible to Interchannel Crosstalk and modelling this in a WDM DPPM system is necessary. Models of varying complexity, based on simplifying assumptions, are presented and evaluated for the case of a single Crosstalk wavelength. For a single Crosstalk, results can be straightforwardly obtained by artificially imposing the computationally convenient constraint that frames (and thus slots also) align. Multiple Crosstalk effects are additionally investigated, for the most practically relevant cases of modest coding level, and using both simulation and analytical methods. In general, DPPM maintains its sensitivity advantage over OOK even in the presence of Crosstalk while predicting lower power penalty at low coding level in WDM systems.
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wdm fso network with turbulence accentuated Interchannel Crosstalk
IEEE\ OSA Journal of Optical Communications and Networking, 2013Co-Authors: A O Aladeloba, M S Woolfson, Andrew J PhillipsAbstract:A wavelength division multiplexing (WDM) access network using high-speed free-space optical (FSO) communication for the distribution link is proposed. Combining FSO communication with optical fiber can reduce the system cost and provide high-bandwidth access in regions where optical fiber installation is problematic. The WDM channels suffer from Interchannel Crosstalk, while the FSO communication performance in a clear atmosphere is limited by atmospherically induced scintillation. These impairments, plus the amplified spontaneous emission noise from optical amplification, combine in a potentially problematic way, particularly in the upstream direction, which is investigated here. This turbulence-accentuated Crosstalk effect is considered for the cases of 1) signal turbulent but Crosstalk not and 2) Crosstalk turbulent but signal not. Error floors are obtained in each case. The FSO link length that can be supported in the general case of the hybrid network is investigated.
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performance analysis of dc coupled peak detecting burst mode receiver in the presence of ase noise and Interchannel Crosstalk
Journal of Lightwave Technology, 2010Co-Authors: Tian Jian Zuo, Andrew J PhillipsAbstract:The bit-error-rate (BER) performance of an optically preamplified peak detecting burst mode (BM) receiver is analyzed. The analysis takes into account amplified spontaneous emission (ASE) noise and, for the first time with this receiver architecture, Interchannel Crosstalk. Furthermore, the ASE beat noises are more appropriately included through the use of a noncentral chi-square (NCCS) distribution in contrast to earlier attempts, which used a Gaussian approximation (GA), though a GA is also developed here for the Interchannel Crosstalk case, for comparative purposes. Results are presented in terms of BER and penalty curves. The peak detector-based BM receiver shows larger threshold acquisition (TA) penalty than an integrator-based BM receiver in the presence of ASE. Also ASE beat noise modeling using the NCCS distribution shows greater power penalty for Interchannel Crosstalk than does the GA. The sum of separate Crosstalk and TA penalties is found to be less than the combined TA penalty obtained in the presence of Interchannel Crosstalk.
Takaaki Ishigure - One of the best experts on this subject based on the ideXlab platform.
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circular core single mode 3 dimensional crossover polymer waveguides fabricated with the mosquito method
Optics Express, 2019Co-Authors: Omar Faruk Rasel, Takaaki IshigureAbstract:We experimentally fabricate circular core 3-dimensional (3D) crossover single-mode polymer optical waveguides using a photomask free unique fabrication technique named the Mosquito method for realizing channel shuffling. The 3D crossover structure is accomplished by forming four cores (2 ch. × 2 ch.) with different heights: the last two channels cross over the first two channels with horizontal and vertical core bending. We compare the insertion losses between the fabricated 3D single-mode crossover waveguide and 3D S-bend core waveguides fabricated separately, which correspond to the lower and upper channels in the crossover waveguide. Then, we investigate the effect of the core crossover on the loss, and find that almost negligible additional loss is observed. The average insertion losses of this 6-cm long 3D crossover single-mode waveguide are 3.95 and 3.81 dB at 1310 nm, and 5.74 and 4.80 dB at 1550-nm wavelength, for the lower and upper channels, respectively. The Interchannel Crosstalk in this crossover waveguide is observed to be lower than −40 dB, while the 1 dB radial alignment tolerance is ± 1.7 and ± 2.1 µm at 1310 and 1550 nm, respectively. These results suggest that the fabricated circular core single-mode 3D crossover polymer waveguides could have a great impact for high-bandwidth-density on-board and inter-chip optical interconnect applications.
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analysis of Interchannel Crosstalk in multimode parallel optical waveguides using the beam propagation method
Optics Express, 2014Co-Authors: Takuya Kudo, Takaaki IshigureAbstract:We theoretically analyze the origin of inter-channel Crosstalk in densely aligned multimode parallel optical waveguides for on-board interconnects using the Beam Propagation Method. In this paper, we demonstrate that the inter-channel Crosstalk due to mode coupling is very low in graded-index (GI) circular-core waveguides because the propagation constants of the propagating modes are discrete. Additionally, it is also found that the waveguides with GI-type circular cores is sensitive to the optical confinement in the cladding: low-power cladding modes largely decrease the mode conversion.
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polymer optical waveguides with gi and w shaped cores for high bandwidth density on board interconnects
Journal of Lightwave Technology, 2013Co-Authors: Ryota Kinoshita, Kimio Moriya, Koji Choki, Takaaki IshigureAbstract:We fabricate polynorbornene-based graded-index (GI) core polymer optical waveguides using the photoaddressing method, and demonstrate that the GI-core polymer waveguides are capable of realizing high-bandwidth-density on-board optical interconnects. Because of the tight optical confinement effect of the parabolic refractive index profile, the fabricated GI-core polymer waveguides exhibit superior optical properties compared to step-index (SI) core polymer waveguides: low propagation loss, low connection loss with GI multimode fiber (MMF) with wide misalignment tolerance, and low Interchannel Crosstalk even under a small pitch size are experimentally confirmed. Furthermore, Interchannel Crosstalk due to multicore operation is experimentally evaluated, and a method to estimate the Interchannel Crosstalk in multimode polymer parallel optical waveguides under multicore operation is proposed for the first time, to the best of our knowledge. The photoaddressing method capable of fabricating even low-loss GI-core polymer waveguide circuits will pave the way for realizing low-cost and high-bandwidth-density optical printed circuit boards.
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fabrication of a graded index circular core polymer parallel optical waveguide using a microdispenser for a high density optical printed circuit board
IEEE Journal of Selected Topics in Quantum Electronics, 2013Co-Authors: Kazutomo Soma, Takaaki IshigureAbstract:A simple fabrication method for multimode polymer optical waveguides with graded-index (GI) circular cores is introduced for use in optical printed circuit boards (O-PCBs). The new method, named “Mosquito method,” utilizes a microdispenser to dispense a viscous monomer directly onto the substrates. By optimizing the dispensing conditions, 12-channel parallel waveguides with circular GI-cores (core diameter of 40 μm) are successfully fabricated using the Mosquito method. The advantages of GI-core waveguides for O-PCB applications are discussed by comparing the optical characteristics of the fabricated waveguides with those of conventional step-index (SI) square-core polymer waveguides, and even with those of silica-based GI multimode fibers (MMFs), as an ideal case. To the best of our knowledge, this is the first comparison of SI- and GI-core multimode polymer waveguides that are composed of the same polymer materials and that have similar core and pitch sizes. We experimentally demonstrate that the GI circular-core polymer waveguides fabricated by the Mosquito method have sufficiently low propagation loss (0.033 dB/cm at 850 nm), low connection loss with GI-MMFs, and low Interchannel Crosstalk. We observe approximately -50 dB of Interchannel Crosstalk in the 250-μm pitch GI-core waveguide fabricated, which is almost 10 dB lower than in the SI counterpart. Furthermore, sufficiently low Crosstalk is maintained in a half-pitch GI-core waveguide fabricated by the Mosquito method.
A.l. Campillo - One of the best experts on this subject based on the ideXlab platform.
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Interchannel Crosstalk Reduction in an Analog Fiber Link Using Dispersion Management
IEEE Photonics Technology Letters, 2008Co-Authors: B.s. Marks, Curtis R. Menyuk, A.l. Campillo, F. BucholtzAbstract:It has previously been shown that dispersion compensation can dramatically affect the Interchannel Crosstalk in a multichannel analog fiber transmission link. In this work, we use a genetic algorithm to find five-segment dispersion maps that yield low Crosstalk levels over two octaves of microwave-frequency bandwidth when amplitude modulation is used. The genetic algorithm suggests that optimal dispersion maps have low residual dispersion. Despite the genetic algorithm's ability to optimize dispersion maps with many fibers, it is possible to obtain similar Crosstalk levels from a simpler two-segment design whose dispersion is fully compensated.
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analysis of Interchannel Crosstalk in a dispersion managed analog transmission link
Journal of Lightwave Technology, 2006Co-Authors: B.s. Marks, Curtis R. Menyuk, A.l. Campillo, F. BucholtzAbstract:A technique for computing the effect of cross-phase modulation (XPM) on two copropagating analog channels in an optical fiber link is presented. In this approach, the interaction between the two channels is linearized by keeping the self-phase modulation (SPM) and XPM interactions in the strong optical carrier components only at lowest order and then at the next order, deriving the effect on the modulation components of both channels when the optical carrier is strong relative to the other components of the channel. In contrast to some previously suggested approaches, it is not assumed that the pump is undistorted, and therefore, this method accurately describes distortions due to SPM, XPM, and dispersion management in both channels. This method is easily applied to systems with multiple spans employing dispersion management with loss and gain. The expressions for the received radio frequency power and Crosstalk between the two channels when direct detection is used are then provided. Using this approach, new expressions for the amplitude modulation and phase modulation modes of the two channels are derived, and the way they exchange energy when SPM, XPM, and dispersion are all considered is explained. This method yields excellent agreement between theory and experimental data.
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phase performance of an eight channel wavelength division multiplexed analog delay line
Journal of Lightwave Technology, 2004Co-Authors: A.l. Campillo, E E Funk, D A Tulchinsky, J L Dexter, K J WilliamsAbstract:The design of an eight-channel 25 /spl mu/s wavelength-division-multiplexed (WDM) microwave photonic delay line is described. The performance of the delay line was studied by measuring the temperature dependent relative phase drift between channels and the Interchannel Crosstalk. A simple method for measuring the maximum phase errors produced by the Interchannel Crosstalk is described and used to measure the maximum error on a channel in this system. The use of polarization interleaving and dispersion compensation to reduce the effects of Crosstalk in the system is examined experimentally.
Tatsurou Hiraki - One of the best experts on this subject based on the ideXlab platform.
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Interchannel Crosstalk characteristics of an integrated wdm receiver based on a si ge silica photonic platform
Asia Communications and Photonics Conference 2013 (2013) paper AF1A.1, 2013Co-Authors: Hidetaka Nishi, Rai Kou, Kotaro Takeda, Tai Tsuchizawa, Tatsurou Hiraki, Mitsuo Usui, Toru Miura, Yasuhiko Ishikawa, Kazumi Wada, Hiroshi FukudaAbstract:Interchannel Crosstalk characteristics of a highly-integrated silicon-photonic WDM receiver are experimentally investigated. The high-frequency electrical Crosstalk is well suppressed to about -20 dB by introducing the electrically-isolated structure based on a Si-Ge-silica photonic platform.
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si ge silica monolithic integration platform and its application to a 22 gb s times 16 ch wdm receiver
IEEE Photonics Journal, 2013Co-Authors: Tatsurou Hiraki, Hidetaka Nishi, Kotaro Takeda, Tai Tsuchizawa, Yasuhiko Ishikawa, Kazumi Wada, Hiroshi Fukuda, Koji YamadaAbstract:We describe a Si-Ge-silica monolithic integration platform for telecommunications applications. The monolithic integration process features low-temperature silica film deposition by electron-cyclotron-resonance chemical vapor deposition to prevent thermal damage to Si/Ge active devices. The monolithically integrated Si and SiOx waveguides show propagation losses of 2.8 and 0.9 dB/cm, and the inverse-tapered spot-size converters show a coupling loss of 0.35 dB. We applied the platform to a 22-Gb/s × 16-ch wavelength-division multiplexing receiver, in which a 16-ch SiOx arrayed waveguide grating (AWG) with 1.6-nm channel separation and Ge photodiodes (PDs) are monolithically integrated. The AWG-PD device exhibits fiber-to-PD responsivity of 0.29 A/W and Interchannel Crosstalk of less than -22 dB and successfully receives 22-Gb/s signal for all 16 channels. In addition, we demonstrate 40-km transmission of 12.5-Gb/s signal and obtain sensitivity of -6.8 dBm at a bit error rate of 10-9 without transimpedance amplifiers.
N A Riza - One of the best experts on this subject based on the ideXlab platform.
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compact switched retroreflection based 2 spl times 2 optical switching fabric for wdm applications
Journal of Lightwave Technology, 2005Co-Authors: N A Riza, Nicholas MadamopoulosAbstract:A low-Interchannel-Crosstalk 2/spl times/2 optical switch is proposed and analyzed. The switch is polarization independent and is based on a novel switch-retroreflection architecture and standard fiber-optic circulators that offer ease in assembly and compact size. Low Interchannel Crosstalk is accomplished using passive and active noise filters that suppress the leakage noise due to the passive polarization components and the active devices, respectively. Theoretical analysis of the proposed 2/spl times/2 optical switch is performed, and the switch Interchannel Crosstalk and optical insertion loss is estimated under different conditions. A novel system architecture is also proposed that uses the switched-retroreflection-based 2/spl times/2 optical switch and wavelength-division multiplexers/demultiplexers to form an add-drop wavelength-division-multiplexed filter with reduced component count.
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reconfigurable wavelength add drop filtering based on a banyan network topology and ferroelectric liquid crystal fiber optic switches
Journal of Lightwave Technology, 1999Co-Authors: N A Riza, S YuanAbstract:This paper presents a modular optical implementation of a Banyan network by using the physical flexibility of the optical fiber to form the interconnections between compact switching stages based on bulk polarization optics. Specifically, these switching stages use total internal reflection (TIR) prisms with ferroelectric liquid crystal (FLC) polarization rotators to form compact modules. Using this Banyan network implementation, a reconfigurable multiwavelength add-drop filter for wavelength division multiplexed (WDM) applications is proposed. Experimental results for our fiber connected 2 in-2 out FLC-based bulk-optic switching stage gives a /spl sim/6.7 dB optical insertion loss and a /spl sim/-40 dB optical Interchannel Crosstalk level. A low 2 dB optical insertion loss design number is expected with optimized components, realizing high (e.g., 35 /spl mu/s) switching speed and low Crosstalk switching networks.
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low Interchannel Crosstalk high speed fiber optic n spl times n crossconnect switch using polarization optics and ferroelectric liquid crystals
Lasers and Electro-Optics Society Meeting, 1998Co-Authors: S Yuan, N A RizaAbstract:It is highly desirable to have a low loss, high speed, low Interchannel Crosstalk, and light-weight fiber optic N/spl times/N cross-connect switch without any physical moving parts. It is well known that ferroelectric liquid crystals (FLCs) can be used as high-speed polarization switching devices without any moving parts. In a previous letter we have reported a 2/spl times/2 fiber optic FLC switch with low Interchannel Crosstalk and high speed. Hence, in this paper, we propose the use of polarization optics combined with ferroelectric liquid crystals to build a N/spl times/N switch for optical cross-connects.
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low optical Interchannel Crosstalk fast switching speed polarisation independent 2 2 fibre optic switch using ferroelectric liquid crystals
Electronics Letters, 1998Co-Authors: N A Riza, S YuanAbstract:A novel <-34.13 dB optical Interchannel Crosstalk, 35.3 /spl mu/s switching speed, polarisation independent, reversible 2/spl times/2 fibre optic switch is demonstrated using four ferroelectric liquid crystal 90/spl deg/ polarisation rotators sandwiched between cube polarisation beam splitters and combiners that also act as Crosstalk rejection filters. Applications of the switch include multiwavelength add-drop routing.
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low Interchannel Crosstalk wavelength routing switch based on bulk acousto optic tunable filters
Lasers and Electro-Optics Society Meeting, 1997Co-Authors: N A RizaAbstract:The purpose of this paper is to introduce a novel bulk acousto-optic tunable filter (AOTF) based wavelength division multiplexed (WDM) optical routing switch free-space architecture that is designed to greatly suppress leakage noise via both spatial and electronic noise blocking techniques. Such a WDM switch, to the best of the author's knowledge, has not been proposed uses bulk-optics.