yuliang gao - Academia.edu (original) (raw)

Papers by yuliang gao

Journal of Lightwave Technology, 2022

In long haul optical fiber communication networks, whichcan span thousands of kilometers, bandwid... more In long haul optical fiber communication networks, whichcan span thousands of kilometers, bandwidth is at a premium due to the relatively low availability of optical fibers when compared with network traffic demands. Therefore, these networks require the highest performance in the physical layer, with transceivers that are capable of extracting all the available capacity from each optical fiber. Digital coherent transmitters and receivers, which enhance optical transmission systems by using digital signal processing, are essential for achieving this goal. This tutorial discusses the digital signal processing techniques that are used in the design of high performance coherent modems to compensate for adverse channel effects such as fiber impairments and optoelectronic device nonidealities.

2015 European Conference on Optical Communication (ECOC), 2015

A 112Gbit/s single polarization half-cycle 16QAM Nyquist-subcarrier-modulation signal was generat... more A 112Gbit/s single polarization half-cycle 16QAM Nyquist-subcarrier-modulation signal was generated and transmitted over 10km of SMF employing 25Gbps EML and direct detection for short reach communications. This is the highest reported bit rate of direct detected half-cycle 16QAM Nyquist-SCM signal on single wavelength and single polarization.

IEEE Photonics Technology Letters, 2018

Digital signal processing (DSP)-enabled, single-polarization, single-carrier, 16-quadrature ampli... more Digital signal processing (DSP)-enabled, single-polarization, single-carrier, 16-quadrature amplitude modulation (QAM) Nyquist subcarrier modulation using a silicon micro-ring resonator is experimentally demonstrated. A bit error ratio of 3.6×10-3 is achieved in a back-to-back measurement at a bit rate of 104 Gb/s.

Asia Communications and Photonics Conference 2013, 2013

We discuss recent advances in DSP techniques for long-haul systems beyond 100Gb/s as well as adap... more We discuss recent advances in DSP techniques for long-haul systems beyond 100Gb/s as well as adaptive transmissions supporting software-defined flexible transponders and Elastic Optical Networks(EON).

Optical Fiber Communication Conference, 2015

The time domain hybrid QAM enabled flexible transceiver is proposed to adaptively optimize the tr... more The time domain hybrid QAM enabled flexible transceiver is proposed to adaptively optimize the transmission performance in DWDM systems with cascaded ROADMs. Comprehensive performance investigations are conducted for both fixed and flexible grid systems.

Optics express, Jan 6, 2015

Discrete multi-tone (DMT) modulation is an attractive modulation format for short-reach applicati... more Discrete multi-tone (DMT) modulation is an attractive modulation format for short-reach applications to achieve the best use of available channel bandwidth and signal noise ratio (SNR). In order to realize polarization-multiplexed DMT modulation with direct detection, we derive an analytical transmission model for dual polarizations with intensity modulation and direct diction (IM-DD) in this paper. Based on the model, we propose a novel polarization-interleave-multiplexed DMT modulation with direct diction (PIM-DMT-DD) transmission system, where the polarization de-multiplexing can be achieved by using a simple multiple-input-multiple-output (MIMO) equalizer and the transmission performance is optimized over two distinct received polarization states to eliminate the singularity issue of MIMO demultiplexing algorithms. The feasibility and effectiveness of the proposed PIM-DMT-DD system are investigated via theoretical analyses and simulation studies.

36th European Conference and Exhibition on Optical Communication, 2010

ABSTRACT A frequency estimation without removing modulated data phase is proposed for M-QAM coher... more ABSTRACT A frequency estimation without removing modulated data phase is proposed for M-QAM coherent system. In addition, a group of weighted coefficients are introduced for M-QAM phase estimation, resulting in an increment of laser linewidth tolerance.

Optics express, Jan 26, 2015

We experimentally demonstrate improved intra-channel nonlinearity tolerance of the root M-shaped ... more We experimentally demonstrate improved intra-channel nonlinearity tolerance of the root M-shaped pulse (RMP) with respect to the root raised cosine (RRC) pulse in spectrally efficient 128 Gbit/s PDM-16QAM coherent transmission systems. In addition we evaluate the impact of dispersion map and fiber dispersion parameter on the intra-channel nonlinearity tolerance of the RRC pulse and the RMP via both simulation and experimentation. The RMP is shown to have a better nonlinear tolerance than the RRC pulse for most investigated scenarios except for links with zero residual dispersion percentage per span or the zero dispersion region of a fiber. Therefore, the RMP is suitable for extending the maximum reach of spectrally efficient coherent transmission systems in legacy links in addition to currently intensively studied standard single mode fiber (SSMF) based dispersion unmanaged links.

Optics express, Jan 28, 2014

In this work we experimentally investigate the improved intra-channel fiber nonlinearity toleranc... more In this work we experimentally investigate the improved intra-channel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system. The digital signal processing (DSP) for the generation and reception of the SCM signals is described. We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10(-3) and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10(-2). Moreover, we show by simulations that the improved performance of SCM signals is observed over a wide range of baud rates, further indicating the merits of SCM signals in baud-rate flexible agile transmissions and future high-speed optical transport systems.

Optics express, Jan 6, 2014

Modulation format independence is one of the key challenges in digital signal processing (DSP) te... more Modulation format independence is one of the key challenges in digital signal processing (DSP) techniques for future elastic optical transmissions. We proposed a modulation-format-independent blind phase search (MFI-BPS) algorithm for square M-ary quadrature amplitude modulation (M-QAM) systems, in which modulation format recognition (MFR) and carrier phase estimation (CPE), are included and implemented both in a feed-forward manner. Comprehensive simulation and the experimental studies on 224 Gbit/s polarization multiplexing 16-QAM (PM-16QAM) systems demonstrate the feasibility and the effectiveness of the proposed MFI-BPS algorithm.

Optics express, Jan 15, 2014

We propose a simple non-data-aided (or unsupervised) and universal cycle slip detection and corre... more We propose a simple non-data-aided (or unsupervised) and universal cycle slip detection and correction (CS-DC) technique based on locating the minimum of the sliding average of twice estimated phase noise. The CS-DC can be appended to any carrier phase estimation(CPE) technique and is modulation format independent. We analytically derive the probability density function of the CS detection metric and study how the sliding window length and detection threshold affects CS detection performance. Simulation results reveal significant cycle slips reduction for various modulation formats with a residual CS probability of 2 × 10^-7 for single carrier system even in unrealistic highly nonlinear system setups. In addition, we show that a second stage of CS-DC with a different sliding window length can further reduce the cycle slip probability by at least an order of magnitude. We also show that CS-DC is tolerant to inter-channel nonlinearities and residue frequency offs...

Optics express, Jan 28, 2014

We propose an adaptive channel estimation (CE) method for zero-guard-interval (ZGI) coherent opti... more We propose an adaptive channel estimation (CE) method for zero-guard-interval (ZGI) coherent optical (CO)-OFDM systems, and demonstrate its performance in a single channel 28 Gbaud polarization-division multiplexed ZGI CO-OFDM experiment with only 1% OFDM processing overhead. We systematically investigate its robustness against various transmission impairments including residual chromatic dispersion, polarization-mode dispersion, state of polarization rotation, sampling frequency offset and fiber nonlinearity. Both experimental and numerical results show that the adaptive CE-aided ZGI CO-OFDM is highly robust against these transmission impairments in fiber optical transmission systems.

Optics Express, 2011

A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-pola... more A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-polarization (DP)-16-QAM transmission systems. By combining QPSK partitioning, maximum likelihood (ML) detection and phase offset estimation between signals in different polarizations, simulation and experimental results for a 200Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best feedforward CPE reported to date while the computational complexity is at least three times lower compared with other simplified feed-forward CPE techniques.

International Photonics and Optoelectronics Meetings, 2012

This paper reviews some of the recent progress in research community in increasing the spectral e... more This paper reviews some of the recent progress in research community in increasing the spectral efficiency of optical communication systems through the use of high order modulation formats and coherent detection techniques. Some of the possible ways for moving forward will be discussed.

IEEE Signal Processing Magazine, 2014

Journal of Lightwave Technology, 2020

The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high... more The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high-speed transponders employing advanced digital signal processing (DSP) algorithms. This manuscript discusses the motivations for jointly utilizing transmission techniques such as probabilistic shaping and digital sub-carrier multiplexing in digital coherent optical transmissions systems. First, we describe the key-building blocks of modern high-speed DSP-based transponders working at up to 800G per wave. Second, we show the benefits of these transmission methods in terms of system level performance. Finally, we report, to the best of our knowledge, the first long-haul experimental transmissione.g., over 1000 km-with a real-time 7 nm DSP ASIC and digital coherent optics (DCO) capable of data rates up to 1.6 Tb/s using two waves (2 × 800G).

Optical Fiber Communication Conference (OFC) 2019, 2019

We demonstrate a novel fiber nonlinearity post-equalization algorithm using principal component a... more We demonstrate a novel fiber nonlinearity post-equalization algorithm using principal component analysis and neural networks. We achieve ∼0.46 dBQ improvement for 21 Gbaud DP-8QAM transmission over ∼13,000 km deployed fiber with over 90% complexity reduction.

Optical Fiber Communication Conference, 2017

Single-carrier, single-polarization subcarrier modulation systems are demonstrated at a bit rate ... more Single-carrier, single-polarization subcarrier modulation systems are demonstrated at a bit rate of 56 Gb/s using a silicon micro-ring resonator modulator. Transmission over 10 km SMF is achieved for 16-QAM and 32-QAM by compensating for nonlinear signal distortion.

2013 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching, 2013

ABSTRACT We present a frequency offset estimation using a residual carrier that is a by-product o... more ABSTRACT We present a frequency offset estimation using a residual carrier that is a by-product of our previous generation technique[1]. The offset range is extended to half of the symbol rate and is resilient to filtering.

IEEE Photonics Technology Letters, 2017

A 112 Gb/s single-carrier, single-polarization short reach transmission system using a high-bandw... more A 112 Gb/s single-carrier, single-polarization short reach transmission system using a high-bandwidth 1310 nm directly modulated laser is demonstrated. Spectrally-efficient signal generation is achieved by using (i) half-cycle Nyquist subcarrier modulation with 16-ary quadrature-amplitude-modulation, (ii) pre-compensation for the frequency response of the end-toend system, (iii) and a Volterra nonlinear equalizer to postcompensate for the nonlinear modulation dynamics of the laser. Digital signal processing techniques for signal recovery enable transmission over 20 km of standard single mode fiber with a bit error ratio below the 7% overhead hard-decision forward error correction coding threshold of 4:6 10 3 at a received optical power of 5:25 dBm.

Journal of Lightwave Technology, 2022

In long haul optical fiber communication networks, whichcan span thousands of kilometers, bandwid... more In long haul optical fiber communication networks, whichcan span thousands of kilometers, bandwidth is at a premium due to the relatively low availability of optical fibers when compared with network traffic demands. Therefore, these networks require the highest performance in the physical layer, with transceivers that are capable of extracting all the available capacity from each optical fiber. Digital coherent transmitters and receivers, which enhance optical transmission systems by using digital signal processing, are essential for achieving this goal. This tutorial discusses the digital signal processing techniques that are used in the design of high performance coherent modems to compensate for adverse channel effects such as fiber impairments and optoelectronic device nonidealities.

2015 European Conference on Optical Communication (ECOC), 2015

A 112Gbit/s single polarization half-cycle 16QAM Nyquist-subcarrier-modulation signal was generat... more A 112Gbit/s single polarization half-cycle 16QAM Nyquist-subcarrier-modulation signal was generated and transmitted over 10km of SMF employing 25Gbps EML and direct detection for short reach communications. This is the highest reported bit rate of direct detected half-cycle 16QAM Nyquist-SCM signal on single wavelength and single polarization.

IEEE Photonics Technology Letters, 2018

Digital signal processing (DSP)-enabled, single-polarization, single-carrier, 16-quadrature ampli... more Digital signal processing (DSP)-enabled, single-polarization, single-carrier, 16-quadrature amplitude modulation (QAM) Nyquist subcarrier modulation using a silicon micro-ring resonator is experimentally demonstrated. A bit error ratio of 3.6×10-3 is achieved in a back-to-back measurement at a bit rate of 104 Gb/s.

Asia Communications and Photonics Conference 2013, 2013

We discuss recent advances in DSP techniques for long-haul systems beyond 100Gb/s as well as adap... more We discuss recent advances in DSP techniques for long-haul systems beyond 100Gb/s as well as adaptive transmissions supporting software-defined flexible transponders and Elastic Optical Networks(EON).

Optical Fiber Communication Conference, 2015

The time domain hybrid QAM enabled flexible transceiver is proposed to adaptively optimize the tr... more The time domain hybrid QAM enabled flexible transceiver is proposed to adaptively optimize the transmission performance in DWDM systems with cascaded ROADMs. Comprehensive performance investigations are conducted for both fixed and flexible grid systems.

Optics express, Jan 6, 2015

Discrete multi-tone (DMT) modulation is an attractive modulation format for short-reach applicati... more Discrete multi-tone (DMT) modulation is an attractive modulation format for short-reach applications to achieve the best use of available channel bandwidth and signal noise ratio (SNR). In order to realize polarization-multiplexed DMT modulation with direct detection, we derive an analytical transmission model for dual polarizations with intensity modulation and direct diction (IM-DD) in this paper. Based on the model, we propose a novel polarization-interleave-multiplexed DMT modulation with direct diction (PIM-DMT-DD) transmission system, where the polarization de-multiplexing can be achieved by using a simple multiple-input-multiple-output (MIMO) equalizer and the transmission performance is optimized over two distinct received polarization states to eliminate the singularity issue of MIMO demultiplexing algorithms. The feasibility and effectiveness of the proposed PIM-DMT-DD system are investigated via theoretical analyses and simulation studies.

36th European Conference and Exhibition on Optical Communication, 2010

ABSTRACT A frequency estimation without removing modulated data phase is proposed for M-QAM coher... more ABSTRACT A frequency estimation without removing modulated data phase is proposed for M-QAM coherent system. In addition, a group of weighted coefficients are introduced for M-QAM phase estimation, resulting in an increment of laser linewidth tolerance.

Optics express, Jan 26, 2015

We experimentally demonstrate improved intra-channel nonlinearity tolerance of the root M-shaped ... more We experimentally demonstrate improved intra-channel nonlinearity tolerance of the root M-shaped pulse (RMP) with respect to the root raised cosine (RRC) pulse in spectrally efficient 128 Gbit/s PDM-16QAM coherent transmission systems. In addition we evaluate the impact of dispersion map and fiber dispersion parameter on the intra-channel nonlinearity tolerance of the RRC pulse and the RMP via both simulation and experimentation. The RMP is shown to have a better nonlinear tolerance than the RRC pulse for most investigated scenarios except for links with zero residual dispersion percentage per span or the zero dispersion region of a fiber. Therefore, the RMP is suitable for extending the maximum reach of spectrally efficient coherent transmission systems in legacy links in addition to currently intensively studied standard single mode fiber (SSMF) based dispersion unmanaged links.

Optics express, Jan 28, 2014

In this work we experimentally investigate the improved intra-channel fiber nonlinearity toleranc... more In this work we experimentally investigate the improved intra-channel fiber nonlinearity tolerance of digital subcarrier multiplexed (SCM) signals in a single-channel coherent optical transmission system. The digital signal processing (DSP) for the generation and reception of the SCM signals is described. We show experimentally that the SCM signal with a nearly-optimum number of subcarriers can extend the maximum reach by 23% in a 24 GBaud DP-QPSK transmission with a BER threshold of 3.8 × 10(-3) and by 8% in a 24 GBaud DP-16-QAM transmission with a BER threshold of 2 × 10(-2). Moreover, we show by simulations that the improved performance of SCM signals is observed over a wide range of baud rates, further indicating the merits of SCM signals in baud-rate flexible agile transmissions and future high-speed optical transport systems.

Optics express, Jan 6, 2014

Modulation format independence is one of the key challenges in digital signal processing (DSP) te... more Modulation format independence is one of the key challenges in digital signal processing (DSP) techniques for future elastic optical transmissions. We proposed a modulation-format-independent blind phase search (MFI-BPS) algorithm for square M-ary quadrature amplitude modulation (M-QAM) systems, in which modulation format recognition (MFR) and carrier phase estimation (CPE), are included and implemented both in a feed-forward manner. Comprehensive simulation and the experimental studies on 224 Gbit/s polarization multiplexing 16-QAM (PM-16QAM) systems demonstrate the feasibility and the effectiveness of the proposed MFI-BPS algorithm.

Optics express, Jan 15, 2014

We propose a simple non-data-aided (or unsupervised) and universal cycle slip detection and corre... more We propose a simple non-data-aided (or unsupervised) and universal cycle slip detection and correction (CS-DC) technique based on locating the minimum of the sliding average of twice estimated phase noise. The CS-DC can be appended to any carrier phase estimation(CPE) technique and is modulation format independent. We analytically derive the probability density function of the CS detection metric and study how the sliding window length and detection threshold affects CS detection performance. Simulation results reveal significant cycle slips reduction for various modulation formats with a residual CS probability of 2 × 10^-7 for single carrier system even in unrealistic highly nonlinear system setups. In addition, we show that a second stage of CS-DC with a different sliding window length can further reduce the cycle slip probability by at least an order of magnitude. We also show that CS-DC is tolerant to inter-channel nonlinearities and residue frequency offs...

Optics express, Jan 28, 2014

We propose an adaptive channel estimation (CE) method for zero-guard-interval (ZGI) coherent opti... more We propose an adaptive channel estimation (CE) method for zero-guard-interval (ZGI) coherent optical (CO)-OFDM systems, and demonstrate its performance in a single channel 28 Gbaud polarization-division multiplexed ZGI CO-OFDM experiment with only 1% OFDM processing overhead. We systematically investigate its robustness against various transmission impairments including residual chromatic dispersion, polarization-mode dispersion, state of polarization rotation, sampling frequency offset and fiber nonlinearity. Both experimental and numerical results show that the adaptive CE-aided ZGI CO-OFDM is highly robust against these transmission impairments in fiber optical transmission systems.

Optics Express, 2011

A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-pola... more A low-complexity feed-forward carrier phase estimation (CPE) technique is presented for dual-polarization (DP)-16-QAM transmission systems. By combining QPSK partitioning, maximum likelihood (ML) detection and phase offset estimation between signals in different polarizations, simulation and experimental results for a 200Gb/s DP-16-QAM system demonstrate similar linewidth tolerance to the best feedforward CPE reported to date while the computational complexity is at least three times lower compared with other simplified feed-forward CPE techniques.

International Photonics and Optoelectronics Meetings, 2012

This paper reviews some of the recent progress in research community in increasing the spectral e... more This paper reviews some of the recent progress in research community in increasing the spectral efficiency of optical communication systems through the use of high order modulation formats and coherent detection techniques. Some of the possible ways for moving forward will be discussed.

IEEE Signal Processing Magazine, 2014

Journal of Lightwave Technology, 2020

The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high... more The design of application-specific integrated circuits (ASIC) is at the core of modern ultra-high-speed transponders employing advanced digital signal processing (DSP) algorithms. This manuscript discusses the motivations for jointly utilizing transmission techniques such as probabilistic shaping and digital sub-carrier multiplexing in digital coherent optical transmissions systems. First, we describe the key-building blocks of modern high-speed DSP-based transponders working at up to 800G per wave. Second, we show the benefits of these transmission methods in terms of system level performance. Finally, we report, to the best of our knowledge, the first long-haul experimental transmissione.g., over 1000 km-with a real-time 7 nm DSP ASIC and digital coherent optics (DCO) capable of data rates up to 1.6 Tb/s using two waves (2 × 800G).

Optical Fiber Communication Conference (OFC) 2019, 2019

We demonstrate a novel fiber nonlinearity post-equalization algorithm using principal component a... more We demonstrate a novel fiber nonlinearity post-equalization algorithm using principal component analysis and neural networks. We achieve ∼0.46 dBQ improvement for 21 Gbaud DP-8QAM transmission over ∼13,000 km deployed fiber with over 90% complexity reduction.

Optical Fiber Communication Conference, 2017

Single-carrier, single-polarization subcarrier modulation systems are demonstrated at a bit rate ... more Single-carrier, single-polarization subcarrier modulation systems are demonstrated at a bit rate of 56 Gb/s using a silicon micro-ring resonator modulator. Transmission over 10 km SMF is achieved for 16-QAM and 32-QAM by compensating for nonlinear signal distortion.

2013 18th OptoElectronics and Communications Conference held jointly with 2013 International Conference on Photonics in Switching, 2013

ABSTRACT We present a frequency offset estimation using a residual carrier that is a by-product o... more ABSTRACT We present a frequency offset estimation using a residual carrier that is a by-product of our previous generation technique[1]. The offset range is extended to half of the symbol rate and is resilient to filtering.

IEEE Photonics Technology Letters, 2017

A 112 Gb/s single-carrier, single-polarization short reach transmission system using a high-bandw... more A 112 Gb/s single-carrier, single-polarization short reach transmission system using a high-bandwidth 1310 nm directly modulated laser is demonstrated. Spectrally-efficient signal generation is achieved by using (i) half-cycle Nyquist subcarrier modulation with 16-ary quadrature-amplitude-modulation, (ii) pre-compensation for the frequency response of the end-toend system, (iii) and a Volterra nonlinear equalizer to postcompensate for the nonlinear modulation dynamics of the laser. Digital signal processing techniques for signal recovery enable transmission over 20 km of standard single mode fiber with a bit error ratio below the 7% overhead hard-decision forward error correction coding threshold of 4:6 10 3 at a received optical power of 5:25 dBm.