Showing papers by "Zhenping Xing published in 2020"
08 Mar 2020
TL;DR: An O-band SiP MZM design enabling net transmission of 212.5 Gbit/s over 2 (10) km using PAM-8 modulation and 20% SD-FEC, and net 200 G Bit/s back-to-back using Pam-6 and 6.7% HD-Fec is presented.
Abstract: We present an O-band SiP MZM design enabling net transmission of 212.5 (200) Gbit/s over 2 (10) km using PAM-8 modulation and 20% SD-FEC, and net 200 Gbit/s back-to-back using PAM-6 and 6.7% HD-FEC.
21 citations
TL;DR: In this paper, the authors used two single-ended RF signals, each having 2.3-Vpp amplitude only, to drive two 1.5mm modulator segments and transmit data at 80 Gbaud PAM-8 (240 Gbit/s) across 2 km under the 20% soft-decision forward error correction BER threshold of 2E-02.
Abstract: We recently reported for the first time 200 Gbit/s/ $\lambda$ net rate data transmission with a single silicon photonic modulator in an intensity modulation direct detection link. Our demonstration relied on an in-house designed, O-band segmented-electrode MZM. In this article, we detail the optimization of the modulator driving scheme, bandwidth/efficiency trade-off and modulation format enabling this result. We use two single-ended RF signals, each having 2.3-Vpp amplitude only, to drive two 1.5-mm modulator segments and transmit data at 80 Gbaud PAM-8 (240 Gbit/s) across 2 km under the 20% soft-decision forward error correction BER threshold of 2E-02. We further decrease the BER using maximum likelihood sequence detection (MLSD), and discuss the related implications. Additionally, we present the system margins regarding modulator drive voltage, received optical power and equalizer taps. At 240 Gbit/s line rate, the modulator energy consumption is only 73 fJ/bit at the SD-FEC threshold. We finally discuss practical implementation considerations for our system.
19 citations
TL;DR: In this paper, the authors provide an overview of the recent work on developing polarisation handling devices such as polarisation beam splitters and polarisers in indium phosphide and silicon-on-insulator platforms for optical communications and sensing applications.
Abstract: Photonic integrated circuits (PICs) suffer from birefringence due to high-index contrast. Polarisation handling devices improve the performance of the PICs by reducing the polarisation-dependent dispersion and loss. Furthermore, there is a growing interest in building polarisation division multiplexed transceivers using PICs, which require polarisation management. The authors provide an overview of the recent work on developing polarisation handling devices such as polarisation beam splitters and polarisers in indium phosphide and silicon-on-insulator platforms for optical communications and sensing applications. These devices expand the PICs library of polarisation handling devices and can be used to design more complex circuits with advanced or new functionalities.
12 citations
TL;DR: This Letter integrates the cost-minimizing distribution matching (CMDM) in the probability amplitude shaping scheme to generate PS-PAM signals with ultra-short symbol block lengths for reduced serial processing delay.
Abstract: Probabilistic shaping (PS) allows tunable spectral efficiency that is suitable for realizing high throughput intra-data center transceivers. In this Letter, we integrate the cost-minimizing distribution matching (CMDM) in the probability amplitude shaping scheme to generate PS-PAM signals with ultra-short symbol block lengths for reduced serial processing delay. We detail the principle of CMDM and present two different methods of implementation. We demonstrate that CMDM enables the transmission of single wavelength net 200 Gbit/s PS-PAM-8 over 2 km of single-mode fiber (SMF). We show that similar performance is achievable using a constant composition distribution matcher, yet requiring 10 times longer symbol block lengths. We also report, to the best of our knowledge, the first demonstration of net 800 Gbit/s transmission over 2 km of SMF using a packaged 4-λ electro-absorption modulated laser transmitter optical sub-assembly (TOSA).
10 citations
TL;DR: In this article, a 20G silicon-based transmitter and a 25G optically-amplified PIN+TIA-based receiver for 100G PON downstream applications were used to achieve a bit error rate (BER) below the low-density parity-check forward error correction (LDPC-FEC) threshold.
Abstract: We demonstrate 100 Gb/s/ $\lambda $ duo-binary PAM-4 (DB-PAM-4) transmission over 50 km standard single-mode fiber (SMF) in the O-band using a 20G silicon-based transmitter and a 25G optically-amplified PIN+TIA-based receiver for 100G PON downstream applications. Receiver sensitivities of −15, −14.5 and −12 dBm are achieved at a bit error rate (BER) below the low-density parity-check forward error correction (LDPC-FEC) threshold (i.e., $1\times 10^{-2}$ ) in back-to-back (B2B), and after 20 and 50 km, respectively using a 131-tap linear feed-forward equalizer (FFE) at the receiver. According to the results, a power budget of 20 dB can be achieved for 20 km transmission. Furthermore, we report the performance of 99 Gb/s (33 Gbaud) PAM-8 transmission and show that DB-PAM-4 provides 5.3 dB better sensitivity compared to PAM-8 at the LDPC-FEC threshold.
10 citations
TL;DR: The asymmetric direct detection of twin-single sideband (SSB) signals based on a simple receiver front-end composed of one optical filter and two photodiodes is proposed and found that the bit error rate performance of ADD is robust against the relative center wavelength drifting of the optical filter.
Abstract: We propose the asymmetric direct detection (ADD) of twin-single sideband (SSB) signals based on a simple receiver front-end composed of one optical filter and two photodiodes. ADD exploits the photocurrent difference between a filtered and unfiltered signal pair to reconstruct and linearize the received twin-SSB signal with a high electrical spectral efficiency (ESE). We evaluate the performance impact of the critical system parameters on ADD and demonstrate 231 Gb/s net rate 16-QAM twin-SSB transmission with 6.03 b/s/Hz ESE over an 80 km standard single-mode fiber below the ${1} \times {{10}^{ - 2}}$1×10−2 hard-decision forward error correction threshold. We also found that the bit error rate performance of ADD is robust against the relative center wavelength drifting of the optical filter.
9 citations
TL;DR: In this paper, a controlled amount of inter-symbol interference (ISI) was introduced during pulse shaping in a high symbol rate intensity modulation direct detection (IM/DD) system to increase the alternating current (AC) power of the received electrical signal after photo-detection and transimpedance amplification.
Abstract: We propose to introduce a controlled amount of inter-symbol interference (ISI) during pulse shaping in a high symbol rate intensity modulation direct detection (IM/DD) system to increase the alternating current (AC) power of the received electrical signal after photo-detection and transimpedance amplification. We experimentally demonstrate high-speed 4-level pulse amplitude modulation (PAM4) transmissions with a 4-λ coarse wavelength division multiplexing (CWDM) transmitter optical sub-assembly (TOSA) using the proposed scheme. The intentionally introduced ISI is mitigated using either transmitter-side Tomlinson Harashima precoding (THP) or receiver-side feed forward equalization (FFE) aided with a 2-tap post filter and maximum likelihood sequence estimation (MLSE). Both methods enable 4 × 81 Gbaud PAM4 transmission over 2 km of single mode fiber (SMF), with a bit error rate (BER) below the 7% overhead hard-decision forward error correction (HD-FEC) threshold of 3.8 × 10−3, which corresponds to a net rate of >600 Gb/s. We also explore the limit of our system at 10 km. The result shows that an aggregated net rate of 600 Gb/s excluding the HD-FEC overhead can still be achieved by loading different symbol rates onto different wavelength channels.
9 citations
08 Mar 2020
TL;DR: The asymmetric-ISI pulse shaping filter with Tomlinson-Harashima precoding to increase the receiver RF swing is introduced and 102 Gbaud PAM-4 transmission over 2 km with a BER below 3.8∗10−3 using linear equalizer at receiver is demonstrated.
Abstract: We introduce the asymmetric-ISI pulse shaping filter with Tomlinson-Harashima precoding to increase the receiver RF swing, and demonstrate 102 Gbaud PAM-4 transmission over 2 km with a BER below 3.8∗10−3 using linear equalizer at receiver.
9 citations
TL;DR: In this article, the first C-band amplifier-free direct detection (DD) system at beyond 100 G throughput over reaches of 40 and 60 km using a high-power single-sideband transmitter (HPSSBT) was reported.
Abstract: 100 G/λ amplifier-free direct detection (DD) systems beyond 40-km reach are desirable to enable the next generation cost- and power-efficient 800 G-ER optical modules. Though such systems in the O-band have been demonstrated, an interest remains to leverage the investment in long haul C-band transceivers. To our knowledge, this article reports the first C-band amplifier-free DD system at beyond 100 G throughput over reaches of 40 and 60-km using a high-power single-sideband transmitter (HPSSBT). This transmitter configuration allows for a cost-efficient 100 G transceiver for the datacenter interconnect requiring only a single digital-to-analog converter (DAC), a Mach–Zehnder modulator, a single-ended photodiode with integrated trans-impedance amplifier (PD+TIA), and an analog-to-digital converter (ADC). In this article, we studied the performance impact of key system parameters including the digitally regenerated DC component of the photocurrent, the driving voltage, and the launch power. We also characterized the sensitivity impact of the system nonlinearity and demonstrated the transmission of 155.14 Gb/s and 104.67 Gb/s net rate single sideband (SSB) PAM-4 signals over 40-km and 60-km of single-mode fiber (SMF) below the HD-FEC threshold of 3.8 × 10−3, respectively. Due to the colored SNR, we further approached the system capacity by transmitting a probabilistically-shaped multi-subcarrier (PS-MSC) signal, allowing a throughput of 176 Gb/s over a 40-km SMF assuming an SD-FEC with a normalized general mutual information (NGMI) threshold of 0.88.
7 citations
TL;DR: In this article, a symbol-level wavelength-interleaver was employed in conjunction with four-dimensional -4-level pulse amplitude modulation -trellis coded modulation (4D-PAM4-TCM) to improve the system robustness against channel performance discrepancies.
Abstract: In a practical 4- $\lambda $ coarse wavelength division multiplexing (CWDM) intensity modulation direct detection (IM/DD) system, different wavelength channels achieve different transmission performances due to 1) inter-channel component differences and 2) chromatic dispersion (CD) – chirp interaction. Large channel performance discrepancies could significantly degrade the average pre- forward error correction (pre-FEC) bit error rate (BER) performance of the system. To improve the system’s robustness against channel performance discrepancies, we propose to employ a symbol-level wavelength-interleaver in conjunction with four-dimensional - 4-level pulse amplitude modulation - trellis coded modulation (4D-PAM4-TCM). We experimentally compare the performances of the proposed wavelength-interleaved 4D-PAM4-TCM system and a conventional 4D-PAM4-TCM system in a 4- $\lambda \,\,\times100$ Gb/s CWDM IM/DD link over 0–20 km. We observe that the wavelength-interleaved 4D-PAM4-TCM system outperforms the conventional 4D-PAM4-TCM system in terms of receiver sensitivity required at the KP4 FEC threshold when sizable channel performance discrepancies exist in such systems.
3 citations
TL;DR: The asymmetric direct detection (ADD) of polarization division multiplexed single-sideband (PDM-SSB) signals with orthogonal offset carriers with photocurrent difference and X-Pol signal intensity enables not only low-complexity signal linearization but also a simplified receiver front-end.
Abstract: We propose and demonstrate the asymmetric direct detection (ADD) of polarization division multiplexed single-sideband (PDM-SSB) signals with orthogonal offset carriers. ADD exploits the photocurrent difference to eliminate the Y-Pol interference in the X-Pol, and the X-Pol signal intensity to eliminate the X-Pol interference in the Y-Pol without resorting to iterative algorithms. This enables not only low-complexity signal linearization but also a simplified receiver front-end composed of a single optical filter, two single-ended photodiodes and two analog-to-digital converters (ADC). In the experiment, we first perform a parametric study of the proposed scheme at 40 Gbaud in the back-to-back configuration (B2B) to evaluate the performance impact of different system parameters including the carrier to signal power ratio (CSPR), the matched filter roll-off, and the filter guard band. Next, we demonstrate the transmission of 416 Gbit/s PDM 16-QAM signal over 80 km single-mode fiber (SMF) below the soft-decision forward error correction (SD-FEC) threshold of 2×10-2. We also numerically study the effectiveness of a 2×2 multiple-input-multiple-output MIMO equalizer in alleviating the inter-polarization linear crosstalk resulting from the non-orthogonal PDM-SSB signals due to polarization-dependent loss (PDL), which is not negligible for potential on-chip implementation of ADD.
01 Sep 2020
TL;DR: In this paper, a broadband 2×2 adiabatic 3dB coupler with an inversely-tapered mode-evolution region for the silicon-on-insulator platform is presented.
Abstract: We report a broadband 2×2 adiabatic 3-dB coupler with an inversely-tapered mode-evolution region for the silicon-on-insulator platform. Measured imbalance better than 0.23 dB is achieved over a 100 nm bandwidth centered at 1550±nm.
01 Dec 2020
TL;DR: In this paper, a filter response aware iterative KK algorithm was proposed to improve the accuracy of SSB signal reconstruction in a vestigial sideband (VSB) system.
Abstract: We propose a filter response aware iterative KK algorithm to improve the accuracy of SSB signal reconstruction in a vestigial sideband (VSB) system. We experimentally and numerically show that this algorithm outperforms conventional KK algorithms in a 100 Gb/s VSB system.
01 Dec 2020
TL;DR: In this paper, an optimization scheme for the distribution of probabilistically shaped signals in practical non-AWGN channels based on a neural network and genetic algorithm is proposed, which enables 23.5% higher throughput than the Maxwell-Boltzmann distribution in a short reach channel with a SiP transmitter.
Abstract: We propose an optimization scheme for the distribution of probabilistically shaped signals in practical non-AWGN channels based on a neural network and genetic algorithm. The optimized input distribution enables 23.5% higher throughput than the Maxwell-Boltzmann distribution in a short reach channel with a SiP transmitter.
TL;DR: An optical time-gate isolator entirely fabricated on the silicon-on-insulator (SOI) platform based on a conventional traveling-wave Mach-Zehnder modulator (TW-MZM) design that achieves time-averaged isolation and can be integrated in larger circuits to protect laser sources or mitigate interference.
Abstract: We demonstrate an optical time-gate isolator entirely fabricated on the silicon-on-insulator (SOI) platform based on a conventional traveling-wave Mach-Zehnder modulator (TW-MZM) design. The device achieves 18.2 dB (22.7 dB) time-averaged isolation when driven with 2.0-Vpp (7.1-Vpp) differential clock signals at 6.8 GHz and biased at null. Under these conditions, the isolator blocks backward light at all time regardless of driver amplitude, but produces periodic modulation in the forward direction. Moreover, we embed our isolator in a digital communication link and measure a signal-to-noise ratio (SNR) penalty of only 0.5 dB due to the isolator at 13.6 Gbaud PAM-4 data rate. Our device can be integrated in larger circuits to protect laser sources or mitigate interference.
13 Jul 2020
TL;DR: In this article, an upsampling-free KK algorithm with frequency-domain implementation of digital resampling was proposed to achieve lower computational complexity than conventional KK in a SP-SSB short-reach link.
Abstract: We determine that with frequency-domain implementation of digital resampling, upsampling-free KK algorithm achieves lower computational complexity than conventional KK algorithm in a SP-SSB short-reach link.