Browsing by Author "Chow, Chi Wai"

Now showing 1 - 11 of 11

56 Gbit/s DMT Signal Generated by an Integrated Silicon Ring Modulator
(2016)
Xu, Ke
;
Wong, Chi Yan
;
Zhang, Liang
;
Liu, Lei
;
Liu, Gordon Ning
We demonstrate a 56 Gb/s DMT signal using a compact silicon microring modulator. The measured bit error rate of back to back modulated signal is well below the FEC limit.
Amplitude and Phase Modulation of UWB Monocycle Pulses on a Silicon Photonic Chip
(2016-02-01)
Xu, Ke
;
Wu, Xinru
;
Sung, Jiun-Yu
;
Cheng, Zhenzhou
;
Chow, Chi Wai
We demonstrate both the amplitude and bi-phase modulation of ultrawideband (UWB) monocycle pulses using silicon microring modulator. The integrated silicon ring modulator generates the monocycle pulse train and modulates it simultaneously. By applying different driving voltages, the amplitude and phase-modulated UWB signal with a data rate of 2.5 Gb/s are achieved. The ring modulator can be thermally tuned for a free spectral range with a similar to 50-mW power consumption.
C plus L band wavelength division multiplexing access network with distributed-controlled protection architecture
(2011-12-01)
Yeh, Chien Hung
;
Chow, Chi Wai
;
光電工程學系
;
Department of Photonics
In this work, we propose and experimentally demonstrate a novel distributed-controlled protection architecture for automatic and fast network restoration in wavelength division multiplexing-passive optical network (WDM-PON). The proposed scheme can support both C and L bands. Besides, duplication of network equipments, such as optical networking unit (ONU) or optical line terminal, is not required. In this distributed-controlled system, each ONU can always keep track of the network status. Hence, this can facilitate the network manage by removing the work loads from the central office. Besides, the proposed scheme can tolerate simultaneous fiber cuts in the feeder and distributed fibers. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3658759]
Cost-effective wavelength-tunable fiber laser using self-seeding Fabry-Perot laser diode
(2008-01-07)
Yeh, Chien Hung
;
Shih, Fu Yuan
;
Wang, Chia Hsuan
;
Chow, Chi Wai
;
Chi, Sien
We propose and experimentally demonstrate a continuous wave (CW) tunable-wavelength fiber laser using self-seeding Fabry-Perot laser diode (FP-LD) without optical amplifier inside gain cavity. By employing a tunable bandpass filter (TBF) and a fiber reflected mirror (FRM) within a gain cavity, the fiber laser can lase a single-longitudinal wavelength due to the self-seeding operation. The proposed tunable wavelength laser has a good performance of the output power (> -15 dBm) and optical side-mode suppression ratio (> 40 dB) in the wavelength tuning range of 1533.75 to 1560.95 nm. In addition, the output stabilities of the fiber laser are also investigated. (c) 2007 Optical Society of America.
Long-Reach Multicast High Split-Ratio Wired and Wireless WDM-PON Using SOA for Remote Upconversion
(2010-11-01)
Xu, Lin
;
Chow, Chi Wai
;
Tsang, Hon Ki
;
光電工程學系
;
Department of Photonics
We propose and experimentally demonstrate a cost-efficient hybrid gigabit wired and wireless long-reach and high split-ratio optical access network based on remote upconversion at the local exchange (LE). The scheme can deliver 40-GHz millimeter-wave wireless services supporting wavelength multicasting over 125-km standard single-mode fiber. A semiconductor optical amplifier (SOA) is used as the multiwavelength broadband optical upconverter and optical power amplifier inside the LE, and a high split-ratio of 512 can be supported. Wavelength multicasting can also be realized with conversion efficiency variation of within 1 dB over 15-nm wavelength range. The SOA has a gain with low polarization dependency and is able to realize multiwavelength operation based on four-wave-mixing for signal upconversion. Results show that the optical millimeter-wave signal distortion due to fiber chromatic dispersion can be significantly mitigated by using the proposed scheme. Expensive RF components are not required at the LE for signal upconversion because the SOA requires only dc bias. The polarization states of the input signals can be controlled at the head-end office; hence, polarization control in the LE may not be required. Error-free transmission for the wired signal was achieved and a power penalty of 2.3 dB was measured after 125-km transmission.
Modeling of Modulation Formats for Interferometric Noise Mitigation
(2008-09-01)
Talli, Giuseppe
;
Chow, Chi Wai
;
Townsend, Paul D.
;
光電工程學系
;
Department of Photonics
Interferometric noise in optical communication systems employing reflective modulation schemes can be mitigated by reshaping the data spectrum to reduce the spectral overlap with backscattered and backreflected light. A novel analytical model, capable of analyzing accurately the performance of modulation formats with a wide optical spectrum, is derived here and applied to study the case of interferometric noise caused by Rayleigh backscattering. Compared to more complex models and simulations the new method is fast, simple to implement, and gives clear insight into the physical phenomena involved. In addition, the performance of practical systems can be easily analyzed and optimized due to the capability of the model to include real component specifications such as arbitrary optical and electrical filter responses. The specific case of phase-modulated non-return to zero (PM-NRZ) modulation format is used to validate the model against experimental results and excellent agreement is obtained. The PM-NRZ performance is also investigated as a function of various parameters, quantifying, for example, the trade-off between phase modulation index and interferometric noise mitigation.
Optical Nyquist filters based on silicon coupled resonator optical waveguides
(2014-10-15)
Xu, Ke
;
Sung, Jiun-Yu
;
Wong, Chi Yan
;
Cheng, Zhenzhou
;
Chow, Chi Wai
We propose an integrated optical Nyquist filter based on silicon coupled resonator optical waveguides (CROW). The designed filter can shape the 28 Gbaud QPSK spectrum to a spectrum having 0.2 roll-off raised cosine shape with G-dB bandwidth equals to the baud rate. The impact of the fabrication tolerance induced coupling coefficients error on the figure of merits of the filter is considered. The filter overall performance is investigated in a Nyquist-WDM system and compared with a 4th order super Gaussian filter. (C) 2014 Elsevier B.V. All rights reserved.
Scalable Ultra-Wideband Pulse Generation Based on Silicon Photonic Integrated Circuits
(2017-11-01)
Wu, Xinru
;
Xu, Ke
;
Zhou, Wen
;
Chow, Chi Wai
;
Tsang, Hon Ki
We demonstrate a scalable ultra-wideband (UWB) pulse generator using silicon photonic integrated circuits. A delay-and-superimpose principle for higher order UWB Guassian pulse generation is realized by monolithically integrating a pair of tunable microring resonators, a delayline waveguide, tap couplers, and an on-chip photodiode. The two microrings function as discrimination filters and generate the asymmetric monocycle pulses. For a proof-of-concept demonstration, the doublet pulses with a 10-dB fractional bandwidth of 100% and the triplet pulses with a 10-dB fractional bandwidth of 132% are generated by superposition of the two asymmetric pulses with a proper delay between them. The proposed scheme and the photonic chip can be scaled to generate more kinds of power-efficient pulses.
Using 10 Gb/s remodulation DPSK signal in self-restored colorless WDM-PON system
(2009-06-01)
Yeh, Chien Hung
;
Chow, Chi Wai
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
In this investigation, we propose and experimentally demonstrate the remodulation technique using DPSK format in both downlink and uplink traffics with high extinction ratio (ER) in colorless WDM-PON; together with a simple self-restored architecture against fiber fault. Error free operation was achieved in a 20-km-reach 10-Gb/s WDM-PON without dispersion compensation. Comparison with other wavelength remodulation schemes for WDM-PONs is also performed, showing the proposed scheme can be a potential candidate for next generation wavelength reuse WDM-PONs. In addition, the performance of self-protection has also been discussed and analyzed. Crown Copyright (C) 2008 Published by Elsevier Inc. All rights reserved.
Utilization of four WDM channels with signal rernodulation of OFDM-QAM for 10 Gb/s uplink passive optical networks
(2009-09-15)
Yeh, Chien Hung
;
Chow, Chi Wai
;
光電工程學系
;
Department of Photonics
In this investigation, we experimentally investigate an extended reach (ER) time-division-multiplexed passive optical network (TDM-PON) using four wavelength-multiplexed channels to achieve 16Gb/s downlink and 10 Gb/s uplink traffic. Each downlink signal uses the highly spectral efficient 4 Gb/s OFDM-QAM, and each uplink signal is generated by signal remodulating the downlink signal via a reflective semiconductor amplifier (RSOA) at 2.5 Gb/s non-return-to-zero (NRZ). In addition, the performance of the proposed ER TDM-PON has also been analyzed and discussed. (c) 2009 Elsevier B.V. All rights reserved.
Utilization of self-injection Fabry-Perot laser diode for long-reach WDM-PON
(2010-01-01)
Shih, Fu Yuan
;
Yeh, Chien Hung
;
Chow, Chi Wai
;
Wang, Chia Hsuan
;
Chi, Sien
In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry-Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation. (c) 2009 Elsevier Inc. All rights reserved.