2012 IEEE Photonics Society Summer Topical Meeting Series, 2012
A novel duobinary RF receiver is proposed and demonstrated based on RF envelope detection for mil... more A novel duobinary RF receiver is proposed and demonstrated based on RF envelope detection for millimeter-wave radio-over-fiber systems. Robust RF downconvertion and duobinary decoding are achieved simultaneously at an RF envelope detector. Duobinary signal delivery over wired and wireless link in coherent single-sideband optical millimeter-wave systems is demonstrated for the first time.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
Advances in high repetition-rate femtosecond laser technology for optical arbitrary waveform gene... more Advances in high repetition-rate femtosecond laser technology for optical arbitrary waveform generation will be described. Combs spanning two octaves, from 500nm to 2μm, based on GHz modelocked Ti:sapphire and erbium-fiber lasers, have been carrier-envelope stabilized and frequency referenced.
We summarize the enabling technologies for photonics-assisted broadband millimeter-wave (mm-wave)... more We summarize the enabling technologies for photonics-assisted broadband millimeter-wave (mm-wave) communication, which is a promising candidate for the enhanced mobile broadband (eMBB) communications, one of the three main typical application scenarios of 5G wireless networks. These enabling technologies, mainly focusing on the improvement of the system structure, include broadband mm-wave signal generation with simple and cost-effective schemes, multiple-input multipleoutput (MIMO) architecture with polarization-multiplexing optical mm-wave signal, advanced multi-level modulation, optical or electrical multi-carrier modulation, antenna polarization multiplexing and the employment of the high-gain mm-wave antenna, multi-band multiplexing, and broadband mm-wave signal detection. We also review the advanced digital signal processing (DSP) for heterodyne coherent detection, which can be applied into the photonics-assisted mm-wave communication systems, to further enhance the system performance for a given system structure and certain available devices. Based on these enabling technologies and advanced DSP, we have realized over 1-Tb/s wireless signal transmission at D-band and over 2.5-km wireless transmission with a bit rate up to 54Gb/s at W-band. Our work verifies the photonics-assisted broadband mm-wave communication can meet the high-data-rate demand of eMBB.
The upcoming new radio access allows ultra-high data rate using millimeter-wave (mm-Wave) frequen... more The upcoming new radio access allows ultra-high data rate using millimeter-wave (mm-Wave) frequencies, while it normally suffers from large path loss. To compensate for path loss, phased arrays for both the transmitter and receiver are used. The 5G new radio (NR) three beam management process proceeds as follows: The transmitted beam is first swept in the downlink direction from the remote radio unit (RRU) to the user equipment (UE), and then the uplink beam is aligned to determine which beam direction has the best reception quality, and vice versa. However, this sequential beam management requires that the RX must be able to perform both beam detection and steering across all the reception angles. Moreover, due to the narrow beamwidth of the phased array operation, a "quantum leap" performance improvement of the receiver operating at mm-Wave is required. In this article, a self-steering array beamformer (SSA-BF) receiving system is proposed, which is composed of a home-designed IC package with zero DC power consumption and a 4-element antenna array. We first conduct the measurement without the antenna, and the SSA-BF receiver shows a significant array factor enhancement with negligible SNR degradation over full field-of-view (FoV) (incidence angle = ±90°), <3 ms fast beam alignment time, and it can support enhanced mobile data-rate up to 10 and 7.8 Gb/s with 20x100 MHz carrier aggregation OFDM in back-to-back and over 25-km fiber transmission, respectively. Moreover, a broadside 3-dB beamwidth ±80°and broadband 17-36 GHz antenna is designed for the proposed SSA-BF receiver in a 5G fiber-wireless access. The SSA-BF receiving system with the 1 × 4 antenna array is designed at 28 GHz, and it shows the normalized array gain better than 3-and 6-dB degradation over broad FoV incidence = ± 68°and ± 85°, respectively. Without any external tuning controls, the proposed SSA-BF achieves the state-of-the-art autonomous beamforming for 6 Gb/s 64-QAM signal over 50-cm wireless distance, achieving a substantial array factor improvement. To the best of authors' knowledge, this is the first demonstration of a high-speed switching SSA-BF receiver in a fiber-wireless integrated radio access as a true enabler for mm-Wave mobile fronthaul applications Index Terms-5G, beamforming, closed-loop, field-of-view (FoV), fiber-wireless network, millimeter-wave (mm-Wave), phased array.
The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optic... more The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optical packet switching system (QOPS) for metro WDM networks. By applying cluster-based wavelength sharing and downsized single-staged optical buffers, QOPS is featured ...
Development of system technology for effective networking infrastructure for next generation e-he... more Development of system technology for effective networking infrastructure for next generation e-health applications is addressed. An integrated optical wireless access architecture based on radio-over-fiber technology is proposed in order to provide super broadband, ultra lowlatency connectivity among various telemedicine modalities to facilitate real-time and near realtime communication for remote health care services.
Small-cell systems based on cloud radio access network (cloud-RAN) architecture have been propose... more Small-cell systems based on cloud radio access network (cloud-RAN) architecture have been proposed as promising solutions to meet the ever-increasing capacity demand of the next-generation wireless access networks. By centralizing the processing power to reduce the complexity of conventional cell sites, the cloud-RAN architecture is ideal for large-scale small-cell system at reduced capital and operational expenses. However, high-speed, flexible, and scalable backhaul links between the centralized baseband processing unit (BBU) and the remote antenna units (RAUs) are required to support the high throughput of the small-cell cloud-RANs, and the conventional approaches are based on digital baseband signal transmission in the backhaul links. In this paper, we propose a novel multi-service small-cell wireless access architecture based on radio-over-fiber (RoF) technologies. By utilizing analog radio frequency (RF) signal transmission in the optical backhaul links, the design of RAUs can...
We have experimentally compared the performances of optical millimeter-wave generation or up-conv... more We have experimentally compared the performances of optical millimeter-wave generation or up-conversion using external modulators based on different modulation schemes. The generated or up-converted optical millimeter wave using the optical carrier suppression (OCS) modulation scheme shows the highest receiver sensitivity, highest spectral efficiency, and smallest power penalty over long-distance delivery. Moreover, the OCS modulation scheme has a simple configuration and low-frequency bandwidth requirement for both electrical and optical components. Employing an OCS modulation scheme, 16-channel dense wavelength-division multiplexing signals at 2.5-Gb/s per channel have been up-converted to a 40-GHz carrier simultaneously.
This paper introduces two radio-over-fiber (RoF) architectures for the future broadband optical-w... more This paper introduces two radio-over-fiber (RoF) architectures for the future broadband optical-wireless access network-all-band RoF and band-mapped 60-GHz RoF that can be integrated in ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON). Legacy wireless services and multi-gigabit millimeter-wave (mm-wave) applications are integrated and delivered simultaneously under one shared infrastructure. With centralized system control and signal processing, the proposed systems provide cost-effective and protocol-transparent solutions for the next-generation multi-service bundle in heterogeneous networks (HetNets). In the all-band RoF network where wireless services are kept at their original carrier frequencies, Wi-Fi, WiMAX, and 60-GHz high-speed mm-wave services are transmitted based on subcarrier multiplexing (SCM) and dual-wavelength heterodyne beating techniques in avoidance of optical filters and large-bandwidth optoelectronic components. In the indoor env...
A channel and latency aware radio resource allocation algorithm based on deep reinforcement learn... more A channel and latency aware radio resource allocation algorithm based on deep reinforcement learning (DRL) is proposed and evaluated. The proposed scheme aims to optimize the uplink scheduling for service-oriented multiuser millimeter wave (mmWave) radio access networks (RAN) in the 5G era. In the DRL system, multiple application flows are implemented with various statistical models and the key function modules of the system are designed to reflect the operation and requirements of service-oriented RANs. In particular, the mmWave channel characteristics utilized in the system are collected experimentally and verified via a radio-over-fiber (RoF)-mmWave testbed with dynamic channel variations. Results show that the proposed DRL algorithm can operate adaptively to channel variations and achieve at least 12% average reward improvement compared to conventional single-rule schemes, providing joint improvement of bit error rate and latency performance.
We first demonstrate delta-sigma digitization and coherent transmission of data over cable system... more We first demonstrate delta-sigma digitization and coherent transmission of data over cable system interface specification (DOCSIS) 3.1 signals in a hybrid fiber coax (HFC) network. Twenty 192-MHz DOCSIS 3.1 channels with modulation up to 16384QAM are digitized by a low-pass cascade resonator feedback (CRFB) delta-sigma analog-to-digital converter (ADC) and transmitted over 80-km fiber using coherent single-λ 128-Gb/s dual-polarization (DP) quadrature phase-shift keying (QPSK) and 256-Gb/s DP-16QAM optical links. Both one-bit and two-bit delta-sigma digitization are implemented and supported by the QPSK and 16QAM coherent transmission systems, respectively. To facilitate its practical application in access networks, the coherent system is built using a low-cost narrow-band optical modulator and RF amplifiers. Modulation error ratio (MER) larger than 50 dB is successfully demonstrated for all 20 DOCSIS 3.1 channels, and high-order modulation up to 16384QAM is delivered over fiber for the first time in HFC networks. The raw DOCSIS data capacity is 54 Gb/s with net user information ∼45 Gb/s. Moreover, the bit error ratio (BER) tolerance is evaluated by measuring the MER performance as BER increases. Negligible MER degradation is observed for BER up to 1.5 × 10 −6 and 1.7 × 10 −4 for one-bit and two-bit digitization, respectively.
We propose a simple and reconfigured dispersion-tolerant single sideband (SSB) orthogonal frequen... more We propose a simple and reconfigured dispersion-tolerant single sideband (SSB) orthogonal frequency division multiplexing (OFDM) radio over fiber (RoF) system enabled by digital signal processing (DSP), one in-phase/quadrature (I/Q) modulator and direct-detection. The generated radio frequency (RF) is based on DSP and the frequency can be flexibly adjusted, which can be employed in the future software-defined radio access network (RAN). Based on our proposed system, we have experimentally demonstrated 16-ary quadrature amplitude modulation (16QAM) 21.87-Gb/s 21-GHz and 38-GHz SSB-OFDM RoF signal generation and transmission over 80-km single-mode fiber (SMF), respectively.
We demonstrate a novel frequency-doubled wireless over fiber system to offer multiband services i... more We demonstrate a novel frequency-doubled wireless over fiber system to offer multiband services including baseband, 60-GHz millimeter-wave and 15-GHz microwave without carrier suppression. Multiband wireless signals are successfully transmitted through both fiber and air channels.
Multimode interference (MMI) devices operating at high data rates are important for integrated op... more Multimode interference (MMI) devices operating at high data rates are important for integrated optics and optical networks. Their 1×N splitting provides a basic functionality in these applications. Ultra-high speed data transmission at 40 Gb/s per channel with a total bandwidth of 320 Gb/s for all 8 output ports is demonstrated for the first time on a 1 × 8 photo-definable polymer-based MMI power splitter. The transmission integrity is confirmed by the bit-error-rate (BER) testing. To further predict the speed limitations of MMI devices, ultrashort pulse response of these devices is quantified. For example, for 20 f s Gaussian input pulses into a 1 × 8 polymer-based MMI splitter, the output pulses are severely degraded in coupling efficiency (47%) and completely broken up in time and in space primarily due to intermodal and intra-modal (waveguide) dispersions.
We propose and demonstrate a novel sub-Nyquist sampling technique for bandwidth-efficient and har... more We propose and demonstrate a novel sub-Nyquist sampling technique for bandwidth-efficient and hardware-efficient mobile fronthaul supporting massive MIMO, simultaneously achieving 32-fold reduction in sampling rate and 1.5-dB improvement in performance in a 128×128 MIMO experiment.
56th Electronic Components and Technology Conference 2006, 2006
We have developed a parallel process for the cost effective fabrication of active lightwave circu... more We have developed a parallel process for the cost effective fabrication of active lightwave circuits and optical transceivers. In this novel process no out-of-plane beam turning components (mirrors or lenses) are used and light never leaves the waveguide except at the photodetector
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
There is a strong interest in providing both broadband wireless and wired access services in the ... more There is a strong interest in providing both broadband wireless and wired access services in the emerging optical-wireless networks [1-8]. We proposed a novel ROF architecture which provides not only wireless based access at carried band in high frequency, but optical fiber based ...
We propose and experimentally demonstrate a method for sampling frequency offset (SFO) estimation... more We propose and experimentally demonstrate a method for sampling frequency offset (SFO) estimation in optical communication systems based on periodically inserted identical binary prefix. Different from conventional cyclic prefix, binary prefix provides not only high tolerance to chromatic dispersion in dispersive fiber transmission, but also the ability to estimate SFO by simple receiver-side digital signal processing. Moreover, this binary prefix based scheme is generally applicable to any advanced modulation formats. A proof-of-concept experiment is conducted to quantify the accuracy and tolerance of the scheme in estimating SFO. It is found that over a wide SFO range up to 341 ppm, the estimation error is kept under 20 ppb and signals are recovered with the same quality as with zero-offset sampling. The experimental results also confirm that this method is tolerant to link signal-to-noise ratio loss and dispersion, showing no additional penalty after transmission over a 40-km sta...
33rd European Conference and Exhibition on Optical Communication - ECOC 2007, 2007
Page 1. 100Gbit/s packet generation with spectral efficiency larger than 1bit/Hz/s by using optic... more Page 1. 100Gbit/s packet generation with spectral efficiency larger than 1bit/Hz/s by using optical carrier suppression and separation and vestigial sideband filtering techniques Jianjun Yu1, Lei Xu1, Philip Nan Ji1, Zhensheng ...
2012 IEEE Photonics Society Summer Topical Meeting Series, 2012
A novel duobinary RF receiver is proposed and demonstrated based on RF envelope detection for mil... more A novel duobinary RF receiver is proposed and demonstrated based on RF envelope detection for millimeter-wave radio-over-fiber systems. Robust RF downconvertion and duobinary decoding are achieved simultaneously at an RF envelope detector. Duobinary signal delivery over wired and wireless link in coherent single-sideband optical millimeter-wave systems is demonstrated for the first time.
2011 XXXth URSI General Assembly and Scientific Symposium, 2011
Advances in high repetition-rate femtosecond laser technology for optical arbitrary waveform gene... more Advances in high repetition-rate femtosecond laser technology for optical arbitrary waveform generation will be described. Combs spanning two octaves, from 500nm to 2μm, based on GHz modelocked Ti:sapphire and erbium-fiber lasers, have been carrier-envelope stabilized and frequency referenced.
We summarize the enabling technologies for photonics-assisted broadband millimeter-wave (mm-wave)... more We summarize the enabling technologies for photonics-assisted broadband millimeter-wave (mm-wave) communication, which is a promising candidate for the enhanced mobile broadband (eMBB) communications, one of the three main typical application scenarios of 5G wireless networks. These enabling technologies, mainly focusing on the improvement of the system structure, include broadband mm-wave signal generation with simple and cost-effective schemes, multiple-input multipleoutput (MIMO) architecture with polarization-multiplexing optical mm-wave signal, advanced multi-level modulation, optical or electrical multi-carrier modulation, antenna polarization multiplexing and the employment of the high-gain mm-wave antenna, multi-band multiplexing, and broadband mm-wave signal detection. We also review the advanced digital signal processing (DSP) for heterodyne coherent detection, which can be applied into the photonics-assisted mm-wave communication systems, to further enhance the system performance for a given system structure and certain available devices. Based on these enabling technologies and advanced DSP, we have realized over 1-Tb/s wireless signal transmission at D-band and over 2.5-km wireless transmission with a bit rate up to 54Gb/s at W-band. Our work verifies the photonics-assisted broadband mm-wave communication can meet the high-data-rate demand of eMBB.
The upcoming new radio access allows ultra-high data rate using millimeter-wave (mm-Wave) frequen... more The upcoming new radio access allows ultra-high data rate using millimeter-wave (mm-Wave) frequencies, while it normally suffers from large path loss. To compensate for path loss, phased arrays for both the transmitter and receiver are used. The 5G new radio (NR) three beam management process proceeds as follows: The transmitted beam is first swept in the downlink direction from the remote radio unit (RRU) to the user equipment (UE), and then the uplink beam is aligned to determine which beam direction has the best reception quality, and vice versa. However, this sequential beam management requires that the RX must be able to perform both beam detection and steering across all the reception angles. Moreover, due to the narrow beamwidth of the phased array operation, a "quantum leap" performance improvement of the receiver operating at mm-Wave is required. In this article, a self-steering array beamformer (SSA-BF) receiving system is proposed, which is composed of a home-designed IC package with zero DC power consumption and a 4-element antenna array. We first conduct the measurement without the antenna, and the SSA-BF receiver shows a significant array factor enhancement with negligible SNR degradation over full field-of-view (FoV) (incidence angle = ±90°), <3 ms fast beam alignment time, and it can support enhanced mobile data-rate up to 10 and 7.8 Gb/s with 20x100 MHz carrier aggregation OFDM in back-to-back and over 25-km fiber transmission, respectively. Moreover, a broadside 3-dB beamwidth ±80°and broadband 17-36 GHz antenna is designed for the proposed SSA-BF receiver in a 5G fiber-wireless access. The SSA-BF receiving system with the 1 × 4 antenna array is designed at 28 GHz, and it shows the normalized array gain better than 3-and 6-dB degradation over broad FoV incidence = ± 68°and ± 85°, respectively. Without any external tuning controls, the proposed SSA-BF achieves the state-of-the-art autonomous beamforming for 6 Gb/s 64-QAM signal over 50-cm wireless distance, achieving a substantial array factor improvement. To the best of authors' knowledge, this is the first demonstration of a high-speed switching SSA-BF receiver in a fiber-wireless integrated radio access as a true enabler for mm-Wave mobile fronthaul applications Index Terms-5G, beamforming, closed-loop, field-of-view (FoV), fiber-wireless network, millimeter-wave (mm-Wave), phased array.
The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optic... more The paper presents the architecture and experimentation of a 10-Gb/s QoS-enabled almost-all-optical packet switching system (QOPS) for metro WDM networks. By applying cluster-based wavelength sharing and downsized single-staged optical buffers, QOPS is featured ...
Development of system technology for effective networking infrastructure for next generation e-he... more Development of system technology for effective networking infrastructure for next generation e-health applications is addressed. An integrated optical wireless access architecture based on radio-over-fiber technology is proposed in order to provide super broadband, ultra lowlatency connectivity among various telemedicine modalities to facilitate real-time and near realtime communication for remote health care services.
Small-cell systems based on cloud radio access network (cloud-RAN) architecture have been propose... more Small-cell systems based on cloud radio access network (cloud-RAN) architecture have been proposed as promising solutions to meet the ever-increasing capacity demand of the next-generation wireless access networks. By centralizing the processing power to reduce the complexity of conventional cell sites, the cloud-RAN architecture is ideal for large-scale small-cell system at reduced capital and operational expenses. However, high-speed, flexible, and scalable backhaul links between the centralized baseband processing unit (BBU) and the remote antenna units (RAUs) are required to support the high throughput of the small-cell cloud-RANs, and the conventional approaches are based on digital baseband signal transmission in the backhaul links. In this paper, we propose a novel multi-service small-cell wireless access architecture based on radio-over-fiber (RoF) technologies. By utilizing analog radio frequency (RF) signal transmission in the optical backhaul links, the design of RAUs can...
We have experimentally compared the performances of optical millimeter-wave generation or up-conv... more We have experimentally compared the performances of optical millimeter-wave generation or up-conversion using external modulators based on different modulation schemes. The generated or up-converted optical millimeter wave using the optical carrier suppression (OCS) modulation scheme shows the highest receiver sensitivity, highest spectral efficiency, and smallest power penalty over long-distance delivery. Moreover, the OCS modulation scheme has a simple configuration and low-frequency bandwidth requirement for both electrical and optical components. Employing an OCS modulation scheme, 16-channel dense wavelength-division multiplexing signals at 2.5-Gb/s per channel have been up-converted to a 40-GHz carrier simultaneously.
This paper introduces two radio-over-fiber (RoF) architectures for the future broadband optical-w... more This paper introduces two radio-over-fiber (RoF) architectures for the future broadband optical-wireless access network-all-band RoF and band-mapped 60-GHz RoF that can be integrated in ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON). Legacy wireless services and multi-gigabit millimeter-wave (mm-wave) applications are integrated and delivered simultaneously under one shared infrastructure. With centralized system control and signal processing, the proposed systems provide cost-effective and protocol-transparent solutions for the next-generation multi-service bundle in heterogeneous networks (HetNets). In the all-band RoF network where wireless services are kept at their original carrier frequencies, Wi-Fi, WiMAX, and 60-GHz high-speed mm-wave services are transmitted based on subcarrier multiplexing (SCM) and dual-wavelength heterodyne beating techniques in avoidance of optical filters and large-bandwidth optoelectronic components. In the indoor env...
A channel and latency aware radio resource allocation algorithm based on deep reinforcement learn... more A channel and latency aware radio resource allocation algorithm based on deep reinforcement learning (DRL) is proposed and evaluated. The proposed scheme aims to optimize the uplink scheduling for service-oriented multiuser millimeter wave (mmWave) radio access networks (RAN) in the 5G era. In the DRL system, multiple application flows are implemented with various statistical models and the key function modules of the system are designed to reflect the operation and requirements of service-oriented RANs. In particular, the mmWave channel characteristics utilized in the system are collected experimentally and verified via a radio-over-fiber (RoF)-mmWave testbed with dynamic channel variations. Results show that the proposed DRL algorithm can operate adaptively to channel variations and achieve at least 12% average reward improvement compared to conventional single-rule schemes, providing joint improvement of bit error rate and latency performance.
We first demonstrate delta-sigma digitization and coherent transmission of data over cable system... more We first demonstrate delta-sigma digitization and coherent transmission of data over cable system interface specification (DOCSIS) 3.1 signals in a hybrid fiber coax (HFC) network. Twenty 192-MHz DOCSIS 3.1 channels with modulation up to 16384QAM are digitized by a low-pass cascade resonator feedback (CRFB) delta-sigma analog-to-digital converter (ADC) and transmitted over 80-km fiber using coherent single-λ 128-Gb/s dual-polarization (DP) quadrature phase-shift keying (QPSK) and 256-Gb/s DP-16QAM optical links. Both one-bit and two-bit delta-sigma digitization are implemented and supported by the QPSK and 16QAM coherent transmission systems, respectively. To facilitate its practical application in access networks, the coherent system is built using a low-cost narrow-band optical modulator and RF amplifiers. Modulation error ratio (MER) larger than 50 dB is successfully demonstrated for all 20 DOCSIS 3.1 channels, and high-order modulation up to 16384QAM is delivered over fiber for the first time in HFC networks. The raw DOCSIS data capacity is 54 Gb/s with net user information ∼45 Gb/s. Moreover, the bit error ratio (BER) tolerance is evaluated by measuring the MER performance as BER increases. Negligible MER degradation is observed for BER up to 1.5 × 10 −6 and 1.7 × 10 −4 for one-bit and two-bit digitization, respectively.
We propose a simple and reconfigured dispersion-tolerant single sideband (SSB) orthogonal frequen... more We propose a simple and reconfigured dispersion-tolerant single sideband (SSB) orthogonal frequency division multiplexing (OFDM) radio over fiber (RoF) system enabled by digital signal processing (DSP), one in-phase/quadrature (I/Q) modulator and direct-detection. The generated radio frequency (RF) is based on DSP and the frequency can be flexibly adjusted, which can be employed in the future software-defined radio access network (RAN). Based on our proposed system, we have experimentally demonstrated 16-ary quadrature amplitude modulation (16QAM) 21.87-Gb/s 21-GHz and 38-GHz SSB-OFDM RoF signal generation and transmission over 80-km single-mode fiber (SMF), respectively.
We demonstrate a novel frequency-doubled wireless over fiber system to offer multiband services i... more We demonstrate a novel frequency-doubled wireless over fiber system to offer multiband services including baseband, 60-GHz millimeter-wave and 15-GHz microwave without carrier suppression. Multiband wireless signals are successfully transmitted through both fiber and air channels.
Multimode interference (MMI) devices operating at high data rates are important for integrated op... more Multimode interference (MMI) devices operating at high data rates are important for integrated optics and optical networks. Their 1×N splitting provides a basic functionality in these applications. Ultra-high speed data transmission at 40 Gb/s per channel with a total bandwidth of 320 Gb/s for all 8 output ports is demonstrated for the first time on a 1 × 8 photo-definable polymer-based MMI power splitter. The transmission integrity is confirmed by the bit-error-rate (BER) testing. To further predict the speed limitations of MMI devices, ultrashort pulse response of these devices is quantified. For example, for 20 f s Gaussian input pulses into a 1 × 8 polymer-based MMI splitter, the output pulses are severely degraded in coupling efficiency (47%) and completely broken up in time and in space primarily due to intermodal and intra-modal (waveguide) dispersions.
We propose and demonstrate a novel sub-Nyquist sampling technique for bandwidth-efficient and har... more We propose and demonstrate a novel sub-Nyquist sampling technique for bandwidth-efficient and hardware-efficient mobile fronthaul supporting massive MIMO, simultaneously achieving 32-fold reduction in sampling rate and 1.5-dB improvement in performance in a 128×128 MIMO experiment.
56th Electronic Components and Technology Conference 2006, 2006
We have developed a parallel process for the cost effective fabrication of active lightwave circu... more We have developed a parallel process for the cost effective fabrication of active lightwave circuits and optical transceivers. In this novel process no out-of-plane beam turning components (mirrors or lenses) are used and light never leaves the waveguide except at the photodetector
2006 Optical Fiber Communication Conference and the National Fiber Optic Engineers Conference, 2006
There is a strong interest in providing both broadband wireless and wired access services in the ... more There is a strong interest in providing both broadband wireless and wired access services in the emerging optical-wireless networks [1-8]. We proposed a novel ROF architecture which provides not only wireless based access at carried band in high frequency, but optical fiber based ...
We propose and experimentally demonstrate a method for sampling frequency offset (SFO) estimation... more We propose and experimentally demonstrate a method for sampling frequency offset (SFO) estimation in optical communication systems based on periodically inserted identical binary prefix. Different from conventional cyclic prefix, binary prefix provides not only high tolerance to chromatic dispersion in dispersive fiber transmission, but also the ability to estimate SFO by simple receiver-side digital signal processing. Moreover, this binary prefix based scheme is generally applicable to any advanced modulation formats. A proof-of-concept experiment is conducted to quantify the accuracy and tolerance of the scheme in estimating SFO. It is found that over a wide SFO range up to 341 ppm, the estimation error is kept under 20 ppb and signals are recovered with the same quality as with zero-offset sampling. The experimental results also confirm that this method is tolerant to link signal-to-noise ratio loss and dispersion, showing no additional penalty after transmission over a 40-km sta...
33rd European Conference and Exhibition on Optical Communication - ECOC 2007, 2007
Page 1. 100Gbit/s packet generation with spectral efficiency larger than 1bit/Hz/s by using optic... more Page 1. 100Gbit/s packet generation with spectral efficiency larger than 1bit/Hz/s by using optical carrier suppression and separation and vestigial sideband filtering techniques Jianjun Yu1, Lei Xu1, Philip Nan Ji1, Zhensheng ...
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Papers by G.K. Chang