Browsing by Author "Tsang, Hon Ki"

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1.12-Tbit/s PAM-4 Enabled by a Silicon Photonic Transmitter Bridged With a 7-Channel MCF
(2020-08-01)
Tong, Yeyu
;
Chen, Guan-Hong
;
Wang, Yi
;
Zhang, Zunyue
;
Chan, David Weng U.
We demonstrate a high-capacity and ultra-compact silicon photonic transmitter directly coupled to a 7-channel multicore fiber (MCF). The integrated transmitter contains seven GeSi electro-absorption modulators (EAMs) connected with the perfectly vertical grating coupler (PVGC) array. A high port density for spatial-division multiplexing (SDM) is thus enabled by the out-of-plane coupling while not requiring angled polishing of the MCF. Relying on four-level pulse amplitude modulation (PAM-4) and digital signal processing (DSP), each of the EAMs can support a data rate of 160 Gbit/s in the back-to-back system. The obtained bit-error-rate (BER) is below the low-latency 7% hard-decision forward-error-correct (HD-FEC) coding limit. The integrated transmitter has a total data-rate-capacity of 1.12 Tbit/s over the seven spatial channels and a compact footprint of 1.8 mm x 0.45 mm. BER performance of the optimum spatial channel is evaluated at different wavelengths, revealing its potential for possible wavelength-division multiplexing (WDM) by the on-chip wavelength (de)multiplexers in the future.
192-Gbit/s PAM-4 Optical Interconnect using Mode-Division Multiplexing
(2018-01-01)
Hsu, Yung
;
Wu, Xinru
;
Chuang, Chun-Yen
;
Chow, Chi-Wai
;
Tsang, Hon Ki
192-Gbit/s pulse-amplitude-modulation-4 (PAM-4) signal transmission for on-chip optical interconnects using mode-division-multiplexing (MDM) is experimentally investigated. 3 channels are successfully mode multiplexed and de-multiplexed satisfying the forward-error correction (FEC) requirement.
2.6 Tbit/s On-Chip Optical Interconnect Supporting Mode-Division-Multiplexing and PAM-4 Signal
(2018-06-01)
Hsu, Yung
;
Chuang, Chun-Yen
;
Wu, Xinru
;
Chen, Guan-Hong
;
Hsu, Chin-Wei
In this letter, we combine the use of dense-wavelength-division-multiplexing and mode-division-multiplexing (MDM) with advanced-modulation formats for on-chip optical interconnects. A three-mode MDM multiplexer (MUX) and de-multiplexer (DEMUX) was designed and used. Each wavelength carrier had an aggregate data rate of 192-Gbit/s using 4-level pulse-amplitude-modulation. The mode crosstalk of the MDM MUX/DEMUX was measured to he below -20 dB in the 40-nm wavelength band from 1520 to 1560 nm. Fourteen wavelength channels are multiplexed and successfully transmitted with an aggregate transmission capacity of 2.6 Tbit/s (14 wavelengths x 3 modes x 64 Gbit/s) with all channels satisfying the hard-decision forward-error-correction threshold. Numerical analysis of the mode crosstalk is also performed.
512-Gbit/s PAM-4 Signals Direct-Detection using Silicon Photonics Receiver with Volterra Equalization
(2018-01-01)
Hsu, Yung
;
Chuang, Chun-Yen
;
Wei, Liang-Yu
;
Chow, Chi-Wai
;
Wu, Xinru
A 400-Gbit/s Ethernet (GbE) pulse-amplitude-modulation-4 (PAM-4) over 10-km single-mode-fiber (SMF) transmission direct-detected by an integrated silicon-photonics-receiver satisfying the IEEE P802.3bs requirement; and its feasibility to support 512-Gbit/s were illustrated.
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.
Compact and High-Speed Ge Franz-Keldysh I/Q Modulator Used with Kramers-Kronig Receiver
(2018-01-01)
Tong, Yeyu
;
Zhang, Qiulin
;
Wu, Xinru
;
Chow, Chi-Wai
;
Shu, Chester
We propose a compact and high-speed FQ modulator based on two germanium-on-silicon Franz-Keldysh electro-absorption modulators. We demonstrate a 4-QAM signal transmission and reconstruct the complex signal in a Kramers-Kronig receiver for future datacenter interconnect applications.
Compatibility of Silicon Mach-Zehnder Modulators for Advanced Modulation Formats
(2013-08-01)
Xu, Ke
;
Yang, Ling-Gang
;
Sung, Jiun-Yu
;
Chen, Yimin M.
;
Cheng, Zhenzhou Z.
Silicon photonics which is compatible with mature complementary metal oxide semiconductor (CMOS) fabrication process has been extensively demonstrated for monolithic integration of photonic and electrical circuits. We show that an integrated silicon Mach-Zehnder modulator (MZM) may be used for advanced modulation formats despite the nonlinear dependence of refractive index change with applied voltage in the free-carrier depletion modulator. We experimentally demonstrated the use of a silicon MZM for direct detection optical orthogonal frequency division multiplexing (DDO-OFDM) modulation with advanced data formats of quadrature phase-shift keying (QPSK), 8 phase-shift keying (8PSK) and 16-quadrature amplitude modulation (16-QAM). The measured bit error rate performance of the back-to-back and 50 km single mode fiber transmission of each format is well below the forward error correction limit.
Integrated germanium-on-silicon Franz-Keldysh vector modulator used with a Kramers-Kronig receiver
(2018-09-15)
Tong, Yeyu
;
Zhang, Qiulin
;
Wu, Xinru
;
Chow, Chi-Wai
;
Shu, Chester
We propose an integrated vector modulator based on two compact and high-speed germanium-on-silicon Franz Keldysh electro-absorption modulators. The proposed vector modulator is extremely compact with a total footprint of only 1800 mu m x 200 mu m. We further experimentally demonstrate a 4-quadrature-amplitude-modulation (4-QAM) at 40 Gb/s over a 20-km standard single-mode fiber transmission. The complex signal is successfully reconstructed with a single-ended photodiode in a recently proposed Kramers-Kronig receiver for future low-cost, low-power, and low-footprint datacenter interconnect applications. The preliminary performance of the vector modulator with a 16-QAM is also investigated. (c) 2018 Optical Society of America.
Integrated Silicon Photonics Remote Radio Frontend (RRF) for Single-Sideband (SSB) Millimeter-Wave Radio-Over-Fiber (ROF) Systems
(2019-04-01)
Tong, Yeyu
;
Chow, Chi-Wai
;
Chen, Guan-Hong
;
Peng, Ching-Wei
;
Yeh, Chien-Hung
Radio-over-fiber (ROF)-based mobile fronthaul network supporting the baseband unit and simple remote radio head is a promising network architecture for future wireless networks. In this paper, we propose and demonstrate a silicon photonics (SiPh)-based remote radio frontend (RRF) for the mm-wave ROF systems. The proposed SiPh-based RRF consisted of an integrated Mach-Zehnder modulator and a micro-ring modulator, producing a single-sideband 40 GHz millimeter-wave orthogonal-frequency-division-multiplexing ROF signal, which is robust against fiber chromatic dispersion in the mobile fronthaul transmission. The RRF is fabricated using SiPh platform and could be potentially low cost. High split-ratios can be potentially achieved. Data rate of 7.813 Gbit/s per wavelength channel is achieved in the experiment. Numerical analysis is also performed; there are good matches of the simulation and experimental results.
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.
Mode-Division-Multiplexing (MDM) of 9.4-Tbit/s OFDM Signals on Silicon-on-Insulator (SOI) Platform
(2019-01-01)
Chen, Guan-Hong
;
Chow, Chi-Wai
;
Yeh, Chien-Hung
;
Peng, Ching-Wei
;
Guo, Pin-Cheng
Silicon photonic (SiPh) technology applied for optical communication systems and network-on-chips have attracted many attentions. We propose and demonstrate the use of a 4 x 4 mode-division-multiplexing (MDM) - multiplexer (MUX) and demultiplexer (DEMUX) to provide 200-Gbit/s orthogonal-frequency-division-multiplexing (OFDM) per wavelength signal transmission. The MDM MUX and DEMUX are implemented by asymmetric directional couplers (ADCs), which are constructed by an access waveguide for the transmission of fundamental mode; and the bus waveguide for the transmission of higher order modes. When phase matching condition is satisfied between the access waveguide and bus waveguide, mode conversion can be achieved. Here, 47 wavelengths are successfully mode multiplexed and de-multiplexed achieving a total transmission capacity 9.4 Tbit/s. Numerically study and analysis of the SiPh MDM MUX/DEMUX are presented, and the experimental evaluations are performed.
Multi-Bound Pulse State in a 250 GHz Mode-Locked Fiber Laser Based on a Silicon Micro-Ring Resonator
(2013-01-01)
Jyu, Siao-Shan
;
Yang, Ling-Gang
;
Wong, Chi Yan
;
Yeh, Chien-Hung
;
Chow, Chi-Wai
A 250 GHz passive mode-locked Er-doped fiber laser with a silicon-based micro-ring resonator is demonstrated experimentally. Besides the single pulse operation at 250 GHz, we also observe an interesting multi-bound pulse operation state.
Optical mm-Wave Signal Generation by Frequency Quadrupling Using an Optical Modulator and a Silicon Microresonator Filter
(2009-01-01)
Xu, Lin
;
Li, Chao
;
Chow, C. W.
;
Tsang, Hon Ki
;
光電工程學系
By adjusting the direct current (de) bias on an electrooptic modulator to suppress the first-order sideband and subsequently using a double-waveguide micro-ring resonator to filter out the optical carrier, millimeter (mm)-wave signal was generated at a frequency of four times the 10-GHz local oscillator. A monolithic integrated silicon-based optical mm-wave signal generator by frequency quadrupling is proposed. A silicon integrated microresonator filter was fabricated and its design parameters are given. High extinction ratio optical mm-wave signal was obtained. The single sideband noise spectrum of the generated 40-GHz optical signal was measured, showing similar performance when compared with that generated by a radio-frequency synthesizer.
Optical Nyquist filters based on silicon coupled resonator optical waveguides
(2014-10-15)
Xu, Ke
;
Sung, Jiun-Yu
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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.
Rayleigh Backscattering Mitigation Using Wavelength Splitting for Heterogeneous Optical Wired and Wireless Access
(2010-09-01)
Chow, C. W.
;
Yeh, Chien Hung
;
Xu, Lin
;
Tsang, Hon Ki
;
光電工程學系
We propose and demonstrate a heterogeneous optical access network using wavelength-splitting at remote-node to mitigate the Rayleigh backscattering (RB) noises. Two continuous-wave carriers are generated from each laser for wired and wireless applications, respectively. Results show that the scheme can effectively mitigate RB noises.
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.