Browsing by Author "Tsang, H. K."

Now showing 1 - 19 of 19

40-Gb/s Upstream Transmitters Using Directly Modulated 1.55-mu m VCSEL Array for High-Split-Ratio PONs
(2010-03-01)
Chow, C. W.
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Xu, L.
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Yeh, C. H.
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Tsang, H. K.
;
Hofmann, W.
We propose and demonstrate a 40-Gb/s symmetric passive optical network with a high split-ratio of 64. The upstream 4 x 10 Gb/s signal is produced by using a directly modulated, uncooled 1.55 mu m monolithic integrated vertical-cavity surface-emitting laser array. The downstream signal is a single-channel 40-Gb/s dark-return-to-zero (DRZ) data, broadcasting information to different optical networking units (ONUs). As the ONU is cost-sensitive, we also demonstrate, by means of simulations, using a 12-Gb/s receiver at the ONU to receive the 40-Gb/s DRZ downstream signal.
Bidirectional colorless wired and wireless WDM-PON with improved dispersion tolerance for radio over fiber
(2011-07-01)
Xu, L.
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Chow, C. W.
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Tsang, H. K.
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光電工程學系
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Department of Photonics
We propose and demonstrate a bidirectional transmission, hybrid wired and wireless access network based on subcarrier modulation (SCM) techniques. The scheme simultaneously enables the dispersion-tolerant transmission of millimeter (mm)-wave signals for use in wireless access networks, downstream baseband signals for optical wired access networks, and optical continuous-wave (CW) carriers for use in upstream data remodulations. Error-free transmissions through a 25-km length of single mode fiber (SMF) for both the downstream baseband and the remodulated upstream signals are confirmed by bit-error-rate (BER) measurements. The dispersion tolerance of the radio-over-fiber (RoF) signal is assessed using numerical simulations. (c) 2011 Elsevier B.V. All rights reserved.
Bidirectional ROF Transmission and Signal Remodulation Using Separate Optical Clock Distribution to Mitigate Signal Distortions
(2009)
Chow, C. W.
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Xu, L.
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Yeh, C. H.
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Wang, C. H.
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Shih, F. Y.
We demonstrate a bidirectional ROF system using a separate optical-clock distribution to mitigate signal-fading and code time-shifting. Error-free signal remodulation using downlink DPSK and uplink OOK was achieved in a 20-km reach ROF system. (C)2009 Optical Society of America
Demonstration of bi-directional LED visible light communication using TDD traffic with mitigation of reflection interference
(2012-10-08)
Liu, Y. F.
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Yeh, C. H.
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Chow, C. W.
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Liu, Y.
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Liu, Y. L.
In this work, we experimentally demonstrate a bi-directional transmission link using light emitting diode (LED) visible light communication (VLC) for both downlink and uplink paths. Time-division-duplex (TDD) is proposed and demonstrated to significantly eliminate the reflection interference in VLC. A free space bi-directional transmission of 2 m using simple on-off keying (OOK) modulation with bit error rate (BER) of < 10(-5) in both directions are achieved. Moreover, the influence of reflection interference is analyzed, showing the proposed scheme can significantly eliminate the reflection interference. (C) 2012 Optical Society of America
Equalization of PAM-4 Signal Generated by Silicon Microring Modulator for 64-Gbit/s Transmission
(2017-11-15)
Tzu, T. C.
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Hsu, Y.
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Chuang, C. Y.
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Wu, X.
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Chow, C. W.
We propose and demonstrate a 64-Gbit/s four-level pulse-amplitude-modulation transmission by using a limited modulation bandwidth silicon microring modulator (SiMRM) and the Volterra equalization scheme. Severe intersymbol interference caused by both the chromatic dispersion of the optical fiber and the bandwidth limitation of components can be compensated. Besides, several equalization schemes are compared and analyzed in terms of performance and complexity. In addition, the design and characteristics of the SiMRM used in the experiment are also discussed.
Frequency Quadrupling of Phase Modulated Signals
(2010-01-01)
Xu, L.
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Li, C.
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Chow, C. W.
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Chen, X.
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Wong, C. Y.
we demonstrate optical up-conversion with frequency quadrupling using an optical phase modulator and a flat-top silicon microresonator filter by beating two second order sidebands at photodetector. 14GHz signal was achieved using 3.5GHz RF components.
Integrated SOT-based Receiver Module for TWDM-PON
(2016)
Hsu, Y.
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Wu, X. R.
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Wei, L. Y.
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Xu, K.
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Hsu, C. W.
We demonstrate a SOl-based integrated receiver (Rx) module for the TWDM-PON. The downstream can be de-multiplexed by a tunable de-multiplexer using cascaded silicon-micro-ring and each channel is received by germanium-on-silicon photodiode.
Investigation of 4-ASK modulation with digital filtering to increase 20 times of direct modulation speed of white-light LED visible light communication system
(2012-07-16)
Yeh, C. H.
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Liu, Y. F.
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Chow, C. W.
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Liu, Y.
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Huang, P. Y.
In this demonstration, we propose and experimentally investigate the quaternary-amplitude-shift-keying (4-ASK) modulation with digital filtering to enhance the direct modulation speed of white-light light-emitting-diode (LED) in visible light communication (VLC) system. Here, an ordinary LED commercially available for lighting application with a direct modulation speed of 1 MHz is used. Data rate of 20 Mbit/s can be achieved in a 1 m free space transmission without using optical blue filter. In the previous studies, the transmission rate of LED VLC could only be increased by 2 to 10 times of the direct modulation speed of the white-light LED if using electrical equalization only. Moreover, the adaptive-controlled FIR filter makes the system closer to the matched filtering condition for reducing the inter-symbol-interference (ISI) for the LED VLC. A recorded 20 times enhancement of the direct modulation speed of white-light LED VLC system is demonstrated by using digital filter only and without using optical blue filter. (C) 2012 Optical Society of America
Long-reach radio-over-fiber signal distribution using single-sideband signal generated by a silicon-modulator
(2011-06-06)
Chow, C. W.
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Yeh, C. H.
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Lo, Stanley M. G.
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Li, C.
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Tsang, H. K.
The integration of passive optical network (PON) and radio-overfiber (ROF) networks could provide broadband services for both fixed and mobile users in a single and low-cost platform. Combining the long-reach (LR)-PON (>100 km) and the LR-ROF can further reduce the cost by simplifying the network architecture, sharing the same optical components and extending the coverage of ROF network. However, the transmission and distribution of ROF signal in LR network is very challenging due to the chromatic dispersion generated periodic power fading and code time-shifting effects in the optical fiber. In this work, we propose and experimentally demonstrate a LR-ROF signal distribution using single-sideband (SSB)-ROF signal generated by a silicon ring-modulator. The silicon modulator is compact and has low power consumption. Besides, one unique feature of the silicon ring-modulator is that it only modulates the signal wavelength at the resonant null. This makes it very suitable for the generation of the SSB-ROF signal. Numerical comparison of the SSB-ROF with the double-sideband (DSB)-ROF and optical carrier suppress (OCS)-ROF signals; as well as the fabrication of the silicon ring-modulator will be discussed. (C)2011 Optical Society of America
Mitigation of Signal Distortions Using Reference Signal Distribution With Colorless Remote Antenna Units for Radio-Over-Fiber Applications
(2009-11-01)
Chow, C. W.
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Xu, L.
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Yeh, C. H.
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Wang, C. H.
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Shih, F. Y.
In this paper, we propose and demonstrate a bidirectional radio-over-fiber (ROF) system using a reference signal distribution. In order to minimize the radio-frequency (RF) signal attenuation as well as limit the transmit power to moderate levels, small cell size, or picocell is used in the ROF system. This will result in the need of many base stations (BSs) to provide sufficient network coverage. Because of this, colorless remote antenna unit (RAU) with optical carrier generated and distributed from the head end (HE) is employed. Experimental results show that error-free signal transmission and remodulation using downstream differential phase shift keying (DPSK) and upstream ON-OFF keying (OOK) is achieved in a 20-km reach ROF system. Experimental characterization of the reflective semiconductor optical amplifier (RSOA)-based remodulation unit is also performed. Numerical simulation is performed to compare the proposed scheme with several conventional optical millimeter-wave (mm-wave) schemes, including double sideband (DSB), optical carrier suppression (OCS), and single sideband (SSB). Results show that the proposed scheme could be a potential candidate to mitigate signal distortions due to signal fading and code time shifting.
Optical frequency doubling for multichannel radio-over-fibre system based on integrated phase modulator and silicon coupled microring notch filter
(2009-06-18)
Xu, L.
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Li, C.
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Tsang, H. K.
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Chow, C. W.
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光電工程學系
An integrated optical millimetre-wave signal generator based on a coupled microring resonator, which doubles the frequency of the electrical signal driving a phase modulator, is proposed and experimentally demonstrated for future radio-over-fibre systems. The coupled microring notch filter was fabricated on a silicon-on-insulator wafer. A high extinction ratio optical millimetre-wave signal was obtained.
Optical frequency doubling for multichannel radio-over-fibre system based on integrated phase modulator and silicon coupled microring notch filter
(2009-06-01)
Xu, L.
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Li, C.
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Tsang, H. K.
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Chow, C. W.
;
光電工程學系
An integrated optical millimetre-wave signal generator based on a coupled microring resonator, which doubles the frequency of the electrical signal driving a phase modulator, is proposed and experimentally demonstrated for future radio-over-fibre systems. The coupled microring notch filter was fabricated on a silicon-on-insulator wafer. A high extinction ratio optical millimetre-wave signal was obtained.
Optical frequency doubling for multichannel radio-over-fibre system based on integrated phase modulator and silicon coupled microring notch filter
(2009-06-01)
Xu, L.
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Li, C.
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Tsang, H. K.
;
Chow, C. W.
;
光電工程學系
An integrated optical millimetre-wave signal generator based on a coupled microring resonator, which doubles the frequency of the electrical signal driving a phase modulator, is proposed and experimentally demonstrated for future radio-over-fibre systems. The coupled microring notch filter was fabricated on a silicon-on-insulator wafer. A high extinction ratio optical millimetre-wave signal was obtained.
Scalable OFDM TWDM-PON using Silicon-based Photonic Devices and Wavelength Tunable Upstream Transmitter
(2014-01-01)
Sung, J. Y.
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Chow, C. W.
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Yeh, C. H.
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Xu, K.
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Tsang, H. K.
We propose and demonstrate a scalable time-wavelength-division-multiplexed passive-optical-network (TWDM-PON) using tunable silicon-micro-ring (SMR) and Ge-Si photodiode as downstream receiver; and wavelength tunable reflective-semiconductor-optical-amplifier (RSOA) ring laser as upstream transmitter.
Stable and wavelength-tunable silicon-micro-ring-resonator based erbium-doped fiber laser
(2013-02-11)
Yang, L. G.
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Yeh, C. H.
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Wong, C. Y.
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Chow, C. W.
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Tseng, F. G.
In this work, we propose and demonstrate a stable and wavelength-tunable erbium-doped fiber (EDF) ring laser. Here, a silicon-on-insulator (SOI)-based silicon-micro-ring-resonator (SMRR) is used as the wavelength selective element inside the fiber ring cavity. A uniform period grating coupler (GC) is used to couple between the SMRR and single mode fiber (SMF) and serves also as a polarization dependent element in the cavity. The output lasing wavelength of the proposed fiber laser can be tuned at a tuning step of 2 nm (defined by the free spectral range (FSR) of the SMRR) in a bandwidth of 35.2 nm (1532.00 to 1567.20 nm), which is defined by the gain of the EDF. The optical-signal-to-noise-ratio (OSNR) of each lasing wavelength is larger than 42.0 dB. In addition, the output stabilities of power and wavelength are also discussed. (C) 2013 Optical Society of America
Transmission Performance Improvement of PAM-4 Signal Direct-Detected by Ge-Si Photodiode using Volterra Equalization
(2017-01-01)
Hsu, Y.
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Chuang, C. Y.
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Chen, G. H.
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Chang, Y. C.
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Wu, X.
We demonstrate a 4-level pulse-amplitude-modulation (PANT-4) transmission system direct-detected by germanium-silicon (Ge-Si) photodiode (PD). Volterra-equalization is used to compensate signal distortion and 40-Gibt/s and 50-Gbit/s PANT-4 signals after 20-km and 10-km fiber transmissions are achieved.
TWDM-PON With Signal Remodulation and Rayleigh Noise Circumvention for NG-PON2
(2013-12-01)
Chow, C. W.
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Yeh, C. H.
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Xu, K.
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Sung, J. Y.
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Tsang, H. K.
We propose and demonstrate a 40-Gb/s (4 x 10 Gb/s) downstream and 10-Gb/s (4 x 2.5 Gb/s) upstream time-wavelength-division-multiplexed passive optical network (TWDM-PON) using signal remodulation. Here, a downstream differential-phase-shift-keying (DPSK) signal and an upstream remodulated carrier-suppressed single-sideband non-return-to-zero (CS-SSB-NRZ) signal are used, which are wavelength shifted to circumvent Rayleigh backscattering (RB). A silicon-based optical microring resonator (MRR) filter is preinstalled at the optical networking unit (ONU) to select the desired downstream wavelength and simultaneously demodulate the downstream DPSK signal, which is then detected by a monolithic-integrated germanium-on-silicon (Ge-Si) photodiode (PD). Using silicon-based devices could be cost effective for the cost-sensitive ONU. The future monolithic integration of a silicon filter, a silicon detector, and a silicon modulator in the ONU is also discussed. The characteristics of the preinstalled silicon-based MRR and the Ge-Si PD are discussed. Error-free transmission (bit-error rate (BER) < 10(-9)) is achieved in both downstream and remodulated upstream signals after propagating through 20 km of standard single-mode fiber (SMF).
Using Wavelength Splitting at the Remote Node to Mitigate Rayleigh Backscattering for Optical Wired and Wireless Access Networks
(2010)
Chow, C. W.
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Xu, L.
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Shih, F. Y.
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Wu, Y. F.
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Yeh, C. H.
We demonstrate an optical wired and wireless access network using wavelength-splitting (WS) at remote-node. A pair of CW carriers is generated from each laser source for wired and wireless applications respectively for effective Rayleigh-backscattering mitigation. (c) 2010 Optical Society of America
Wavelength-tunable Erbium-doped fiber laser using silicon-on-insulator (SOI) based micro-ring with narrow laser linewidth
(2015-01-01)
Yang, L. G.
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Chow, C. W.
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Yeh, C. H.
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Tsang, H. K.
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光電工程學系
We propose and demonstrate a wavelength-tunable and narrow-linewidth erbium-doped fiber (EDF) laser using silicon-on-insulator (SOI) based micro-ring. We discuss the wavelength selection and wavelength-tunable operation of the proposed fiber laser. The SOI based micro-ring is fabricated on a SOI wafer with a 0.22 um thick top silicon layer and a 2 um thick burial oxide (BOX) layer. In order to enhance the coupling efficiency between the SOI based micro-ring and the EDF, a pair of uniform period grating couplers are used. In the experiment, the lasing wavelengths can be tuned in the wavelengths range from 1532 nm to 1567.2 nm with a tuning step of 2 nm. The wavelength range and the tuning step are determined by the EDFA gain-bandwidth and the FSR of the SOI based micro-ring respectively. The OSNR of each lasing wavelength is > 42 dB. By using a double-ring configuration, a narrow laser linewidth of 50 kHz can be achieved.