The Experts below are selected from a list of 27561 Experts worldwide ranked by ideXlab platform
Chi-wai Chow - One of the best experts on this subject based on the ideXlab platform.
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using a single vcsel source employing ofdm downstream Signal and remodulated ook Upstream Signal for bi directional visible light communications
Scientific Reports, 2017Co-Authors: Chien-hung Yeh, Chi-wai Chow, Liang Yu WeiAbstract:In this work, we propose and demonstrate for the first time up to our knowledge, using a 682 nm visible vertical-cavity surface-emitting laser (VCSEL) applied in a bi-directional wavelength remodulated VLC system with a free space transmission distance of 3 m. To achieve a high VLC downstream traffic, spectral efficient orthogonal-frequency-division-multiplexing quadrature-amplitude-modulation (OFDM-QAM) with bit and power loading algorithms are applied on the VCSEL in the central office (CO). The OFDM downstream wavelength is remodulated by an acousto-optic modulator (AOM) with OOK modulation to produce the Upstream traffic in the client side. Hence, only a single VCSEL laser is needed for the proposed bi-directional VLC system, achieving 10.6 Gbit/s OFDM downstream and 2 Mbit/s remodulated OOK Upstream simultaneously. For the proposed system, as a single laser source with wavelength remodulation is used, the laser wavelength and temperature managements at the client side are not needed; and the whole system could be cost effective and energy efficient.
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Using Downstream DPSK and Upstream Wavelength-Shifted ASK for Rayleigh Backscattering Mitigation in TDM-PON to WDM-PON Migration Scheme
IEEE Photonics Journal, 2013Co-Authors: Chi-wai Chow, Chien-hung YehAbstract:A migration scheme from time-division-multiplex passive optical network (TDM-PON) to wavelength-division-multiplex PON (WDM-PON) using differential phase-shift keying (DPSK) for the downstream Signal and wavelength-shifted amplitude-shift keying (WS-ASK) for the Upstream Signal is demonstrated. The migration scheme does not change the existing fiber infrastructure. An optical filter is preinstalled at the optical networking unit (ONU) to select the desirable downstream wavelength for the WDM-PON and simultaneously demodulate the downstream DPSK Signal. Signal remodulation is used to generate the Upstream Signal by reusing the downstream wavelength. In the ONU, by wavelength shifting the Upstream optical spectrum with respect to the downstream optical spectrum, the Rayleigh backscattering (RB) interference beat noise affecting the Upstream Signal can be significantly mitigated. The optimum bandwidth for the downstream DPSK demodulation is analyzed. The downstream and Upstream transmission performances at different split ratios are also discussed.
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extended reach access network with downstream radio over fiber rof Signal and Upstream nrz Signal using orthogonal wdm
Optics Express, 2012Co-Authors: Chi-wai Chow, S P Huang, L G Yang, C H YehAbstract:We propose and demonstrate an extended-reach radio-over-fiber (ROF) access network. The double-sideband carrier-suppressed (DSCS) optical Signal carries the downstream ROF Signal. A continuous wave (CW) optical carrier is embedded into the DSCS optical Signal and transmitted to the colorless optical networking unit (ONU)/remote antenna unit (RAU) for the Upstream Signal generation. At the ONU/RAU, the Upstream data is orthogonally wavelength division multiplexed (WDM) onto this CW carrier; hence mitigating the cross-talk generated by the downstream Signal. Analyses about the optimum power difference between the downstream and the CW Signals; as well as the split-ratio are also preformed.
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Simple Colorless WDM-PON With Rayleigh Backscattering Noise Circumvention Employing $m$ -QAM OFDM Downstream and Remodulated OOK Upstream Signals
Journal of Lightwave Technology, 2012Co-Authors: Chien-hung Yeh, Chi-wai Chow, Hsing-yu ChenAbstract:We propose and experimentally demonstrate a new colorless wavelength-division-multiplexed passive optical network (WDM-PON) architecture with the Rayleigh backscattering (RB) interferometric beat noise mitigation by using cross-remodulation architecture. The proposed WDM-PON has a simply configuration by combining two WDM-PONs at two wavelength bands to support twice the number of users. We experiment different m-quadrature amplitude modulation (QAM) (m = 16, 32 and 64) orthogonal frequency division multiplexing (OFDM) downstream Signal and the remodulated on-off keying (OOK) Upstream Signal by using the 2.5 GHz directly modulated laser (DML) and 1.2 GHz reflective semiconductor optical amplifier (RSOA) respectively. Hence, the total data rate achieved for the downstream Signals are 10 Gb/s, 12.5 Gb/s, and 15 Gb/s respectively for different m -QAM. For the Upstream Signal, we over-drive the RSOA and 2.5 Gb/s OOK Upstream traffic can be achieved. In addition, the proposed PON can also be upgraded to support more wavelength bands to meet the increase demand of capacity.
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mitigation of rayleigh backscattering in 10 gb s downstream and 2 5 gb s Upstream dwdm 100 km long reach pons
Optics Express, 2011Co-Authors: Chi-wai Chow, C H YehAbstract:Long-reach passive optical network (LR-PON) is considered as a promising technology towards higher capacity and extended coverage optical system. We propose and demonstrate a LR-PON with the capability of Rayleigh backscattering (RB) noise mitigation. By using the Upstream Signal wavelength-transition generated by a dual-parallel Mach-Zehnder modulator (DP-MZM) based colorless optical networking unit (ONU), the spectral overlap among the Upstream Signal and the RB noises can be minimized. Hence, due to the achievement of effective RB mitigation, a 100 km LR-PON with a high split-ratio of 512 is demonstrated using 10 Gb/s non-return-to-zero (NRZ) downstream and 2.5 Gb/s NRZ Upstream Signals. Detail analysis of the wavelength-transition generation is presented.
Chien-hung Yeh - One of the best experts on this subject based on the ideXlab platform.
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using a single vcsel source employing ofdm downstream Signal and remodulated ook Upstream Signal for bi directional visible light communications
Scientific Reports, 2017Co-Authors: Chien-hung Yeh, Chi-wai Chow, Liang Yu WeiAbstract:In this work, we propose and demonstrate for the first time up to our knowledge, using a 682 nm visible vertical-cavity surface-emitting laser (VCSEL) applied in a bi-directional wavelength remodulated VLC system with a free space transmission distance of 3 m. To achieve a high VLC downstream traffic, spectral efficient orthogonal-frequency-division-multiplexing quadrature-amplitude-modulation (OFDM-QAM) with bit and power loading algorithms are applied on the VCSEL in the central office (CO). The OFDM downstream wavelength is remodulated by an acousto-optic modulator (AOM) with OOK modulation to produce the Upstream traffic in the client side. Hence, only a single VCSEL laser is needed for the proposed bi-directional VLC system, achieving 10.6 Gbit/s OFDM downstream and 2 Mbit/s remodulated OOK Upstream simultaneously. For the proposed system, as a single laser source with wavelength remodulation is used, the laser wavelength and temperature managements at the client side are not needed; and the whole system could be cost effective and energy efficient.
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Using Downstream DPSK and Upstream Wavelength-Shifted ASK for Rayleigh Backscattering Mitigation in TDM-PON to WDM-PON Migration Scheme
IEEE Photonics Journal, 2013Co-Authors: Chi-wai Chow, Chien-hung YehAbstract:A migration scheme from time-division-multiplex passive optical network (TDM-PON) to wavelength-division-multiplex PON (WDM-PON) using differential phase-shift keying (DPSK) for the downstream Signal and wavelength-shifted amplitude-shift keying (WS-ASK) for the Upstream Signal is demonstrated. The migration scheme does not change the existing fiber infrastructure. An optical filter is preinstalled at the optical networking unit (ONU) to select the desirable downstream wavelength for the WDM-PON and simultaneously demodulate the downstream DPSK Signal. Signal remodulation is used to generate the Upstream Signal by reusing the downstream wavelength. In the ONU, by wavelength shifting the Upstream optical spectrum with respect to the downstream optical spectrum, the Rayleigh backscattering (RB) interference beat noise affecting the Upstream Signal can be significantly mitigated. The optimum bandwidth for the downstream DPSK demodulation is analyzed. The downstream and Upstream transmission performances at different split ratios are also discussed.
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Simple Colorless WDM-PON With Rayleigh Backscattering Noise Circumvention Employing $m$ -QAM OFDM Downstream and Remodulated OOK Upstream Signals
Journal of Lightwave Technology, 2012Co-Authors: Chien-hung Yeh, Chi-wai Chow, Hsing-yu ChenAbstract:We propose and experimentally demonstrate a new colorless wavelength-division-multiplexed passive optical network (WDM-PON) architecture with the Rayleigh backscattering (RB) interferometric beat noise mitigation by using cross-remodulation architecture. The proposed WDM-PON has a simply configuration by combining two WDM-PONs at two wavelength bands to support twice the number of users. We experiment different m-quadrature amplitude modulation (QAM) (m = 16, 32 and 64) orthogonal frequency division multiplexing (OFDM) downstream Signal and the remodulated on-off keying (OOK) Upstream Signal by using the 2.5 GHz directly modulated laser (DML) and 1.2 GHz reflective semiconductor optical amplifier (RSOA) respectively. Hence, the total data rate achieved for the downstream Signals are 10 Gb/s, 12.5 Gb/s, and 15 Gb/s respectively for different m -QAM. For the Upstream Signal, we over-drive the RSOA and 2.5 Gb/s OOK Upstream traffic can be achieved. In addition, the proposed PON can also be upgraded to support more wavelength bands to meet the increase demand of capacity.
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a self protected colorless wdm pon with 2 5 gb s Upstream Signal based on rsoa
Optics Express, 2008Co-Authors: Chien-hung Yeh, Hung-chang Chien, Chi-wai Chow, C H Wang, F Y Shih, Sien ChiAbstract:In this investigation, we propose and demonstrate a colorless wavelength division multiplexed passive optical network (WDM-PON) at 2.5 Gb/s using reflective semiconductor optical amplifier (RSOA)-based optical networking units (ONUs); together with a self-protected architecture against fiber fault. In the optical line terminal (OLT), we use an array of self-seeding Fabry-Perot laser diodes (FP-LDs) to provide single-longitudinal-mode (SLM) continuous wave (CW) optical sources for the external injection to the RSOA-based ONUs. The self-survivable function for protecting the fiber fault in the distributed fibers and the proposed network performance are investigated and discussed.
T Sugie - One of the best experts on this subject based on the ideXlab platform.
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wavelength channel data rewriter using semiconductor optical saturator modulator
Journal of Lightwave Technology, 2006Co-Authors: Hiroki Takesue, Naoto Yoshimoto, Yasuo Shibata, Y Tohmori, T SugieAbstract:A wavelength channel data rewriter (WCDR) is a device that erases the data on an incoming Signal by utilizing the saturation characteristic of a semiconductor optical amplifier (SOA) and then modulates it with new data to generate an Upstream Signal. This paper describes a theoretical and experimental investigation designed to improve the performance of the WCDR. Through numerical calculations, this paper shows that an SOA with a long waveguide with a large small-Signal gain better suppresses optical bit patterns. This paper also uses calculated and experimental results to show that the amplified-spontaneous-emission noise in the SOA input Signal degrades the bit-pattern suppression. This paper then describes the semiconductor optical saturator/modulator (SOSM), which this paper has developed for use in the WCDR based on the results of the author's theoretical investigations. This paper outlines the SOSM specifications and provides experimental results that confirm the improved WCDR performance obtained using the SOSM.
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Wavelength channel data rewriter using semiconductor optical saturator/modulator
Journal of Lightwave Technology, 2006Co-Authors: Hiroki Takesue, Naoto Yoshimoto, Yasuo Shibata, Y Tohmori, Tsuyoshi Ito, T SugieAbstract:A wavelength channel data rewriter (WCDR) is a device that erases the data on an incoming Signal by utilizing the saturation characteristic of a semiconductor optical amplifier (SOA) and then modulates it with new data to generate an Upstream Signal. This paper describes a theoretical and experimental investigation designed to improve the performance of the WCDR. Through numerical calculations, this paper shows that an SOA with a long waveguide with a large small-Signal gain better suppresses optical bit patterns. This paper also uses calculated and experimental results to show that the amplified-spontaneous-emission noise in the SOA input Signal degrades the bit-pattern suppression. This paper then describes the semiconductor optical saturator/modulator (SOSM), which this paper has developed for use in the WCDR based on the results of the author's theoretical investigations. This paper outlines the SOSM specifications and provides experimental results that confirm the improved WCDR performance obtained using the SOSM.
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wavelength channel data rewrite using saturated soa modulator for wdm networks with centralized light sources
Journal of Lightwave Technology, 2003Co-Authors: Hiroki Takesue, T SugieAbstract:This paper describes a method for realizing the efficient utilization of wavelength resources in wavelength-division multiplexing networks with centralized light sources. Using a deeply saturated semiconductor optical amplifier (SOA) modulator located in a remote node (RN), we erase the data on a downstream Signal with a low extinction ratio and modulate it with new data to generate an Upstream Signal. Thus, we use only one wavelength for bidirectional transmission between a center node and an RN, without placing lasers at the RN. In this paper, we analyze the data suppression characteristic of the SOA using a large Signal model. We also estimate the bit error rate degradation in the presence of an unsuppressed downstream bit pattern in an Upstream Signal. We then report experimental results that confirm the basic characteristics of the wavelength channel data rewriter, which we constructed using a linear amplifier and an SOA. Finally, we provide the results of a data transmission experiment that we undertook using the data rewriter.
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data rewrite of wavelength channel using saturated soa modulator for wdm metro access networks with centralized light sources
European Conference on Optical Communication, 2002Co-Authors: H Takesue, T SugieAbstract:We propose a simple wavelength reuse technique for WDM metro/access networks with centralized light sources. Using a deeply saturated SOA modulator located in a remote node, we erase the data on a low-extinction-ratio downstream Signal and modulate it with new data to generate an Upstream Signal.
Soo-min Kang - One of the best experts on this subject based on the ideXlab platform.
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optical Signal suppression by a cascaded soa rsoa for wavelength reusing reflective pon Upstream transmission
Optics Express, 2017Co-Authors: Sang-min Jung, Soo-min KangAbstract:An optical Signal suppression technique based on a cascaded SOA and RSOA is proposed for the reflective passive optical networks (PONs) with wavelength division multiplexing (WDM). By suppressing the downstream Signal of the optical carrier, the proposed reflective PON effectively reuses the downstream optical carrier for Upstream Signal transmission. As an experimental demonstration, we show that the proposed optical Signal suppression technique is effective in terms of the Signal bandwidth and bit-error-rate (BER) performance of the remodulated Upstream transmission.
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Optical Signal suppression by a cascaded SOA/RSOA for wavelength reusing reflective PON Upstream transmission.
Optics Express, 2017Co-Authors: Sang-min Jung, Soo-min KangAbstract:An optical Signal suppression technique based on a cascaded SOA and RSOA is proposed for the reflective passive optical networks (PONs) with wavelength division multiplexing (WDM). By suppressing the downstream Signal of the optical carrier, the proposed reflective PON effectively reuses the downstream optical carrier for Upstream Signal transmission. As an experimental demonstration, we show that the proposed optical Signal suppression technique is effective in terms of the Signal bandwidth and bit-error-rate (BER) performance of the remodulated Upstream transmission.
Sang-min Jung - One of the best experts on this subject based on the ideXlab platform.
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optical Signal suppression by a cascaded soa rsoa for wavelength reusing reflective pon Upstream transmission
Optics Express, 2017Co-Authors: Sang-min Jung, Soo-min KangAbstract:An optical Signal suppression technique based on a cascaded SOA and RSOA is proposed for the reflective passive optical networks (PONs) with wavelength division multiplexing (WDM). By suppressing the downstream Signal of the optical carrier, the proposed reflective PON effectively reuses the downstream optical carrier for Upstream Signal transmission. As an experimental demonstration, we show that the proposed optical Signal suppression technique is effective in terms of the Signal bandwidth and bit-error-rate (BER) performance of the remodulated Upstream transmission.
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Optical Signal suppression by a cascaded SOA/RSOA for wavelength reusing reflective PON Upstream transmission.
Optics Express, 2017Co-Authors: Sang-min Jung, Soo-min KangAbstract:An optical Signal suppression technique based on a cascaded SOA and RSOA is proposed for the reflective passive optical networks (PONs) with wavelength division multiplexing (WDM). By suppressing the downstream Signal of the optical carrier, the proposed reflective PON effectively reuses the downstream optical carrier for Upstream Signal transmission. As an experimental demonstration, we show that the proposed optical Signal suppression technique is effective in terms of the Signal bandwidth and bit-error-rate (BER) performance of the remodulated Upstream transmission.
