High-speed Optical Communication Research Articles

Compact photonic device based on chalcogenide glass loaded lithium niobate on insulator

We propose a hybrid photonic platform based on chalcogenide glass (GeSbSe) integrated with lithium niobate on insulator (LNOI), providing enhanced performance and compactness for integrated photonics. Key photonic components, including grating couplers (GCs), micro-ring resonators, multimode interference (MMI), and the Mach–Zehnder interferometer (MZI), are designed and fabricated on this platform. The micro-ring resonator achieves an intrinsic quality factor of 72,000 and a propagation loss of ∼3 dB/cm. The multimode interference couplers demonstrate minimal excess loss, while the MZI exhibits an extinction ratio exceeding 30 dB over a bandwidth of 50 nm. This hybrid platform, leveraging the unique optical properties of GeSbSe and LNOI, offers scalability and low-loss photonic integrated circuits, with promising applications in high-speed optical communications and signal processing.

Extra-cavity modulating a dark bisoliton

Abstract Although the concept of modulating optical solitons out of fiber laser cavities has already been proposed, to more flexibly change optical solitons’ time or frequency domain properties, compared with traditional intra-cavity modulation. The extra-cavity modulation of dark bisolitons has seldom been touched upon. In this manuscript, we theoretically conduct the research about modulating a dark bisoliton at 1 μm wavelength regime, in an extra-cavity modulation system. The modulation system is composed of different modulation elements. In the simulation, we consider the variations of different parameters. And modulated dark bisoliton’s orthogonal polarization components will show unique variation properties as these soliton parameters vary. For example, as time delay in orthogonal directions varies, a new small pulse peak appears at the position of continuous wave background in vertical polarization direction at output port, when time delay reaches to a specific value. These simulation results further explore the extra-cavity modulation of dark pulses in nonlinear optical fiber modulation systems, which are useful to understand the dark bisolitons’ dynamics in extra-cavity modulation systems. And these results have potential applications in the field of high-speed and long-distance optical fiber communication.

LI-FI Performance Analysis in Various Aquatic Environments for Reliable Underwater Communication

The ability to communicate reliably and quickly underwater has been one of the driving forces behind the development of alternative technologies to conventional radio frequency systems. This study explores the performance of Light Fidelity (Li-Fi), a high-speed optical wireless communication technology, in diverse aquatic environments like fresh water, salt water, and turbid water. It evaluates key parameters like signal attenuation, data rate, bit error rate, and transmission range. Results show that Li-Fi offers significant advantages in bandwidth and data rate over traditional methods, but its efficiency is highly dependent on environmental conditions. The study recommends optimizing Li-Fi systems for reliable underwater communication, paving the way for enhanced underwater networking and data transmission applications.

Investigation of Multiple LED Array Failure on DCO-FBMC Modulation for Indoor Visible Light Communication

Visible light communication (VLC) is a high-speed and power-efficient optical wireless communication method that has gained momentum for data transmission in indoor environments. Indoor VLC systems often use multiple LED arrays to increase the uniformity of brightness and enhance the received energy and the four LED array model is the most commonly used. To suppress the impact of intersymbol interference (ISI) and achieve higher data rates, multicarrier modulation techniques such as orthogonal frequency division multiplexing (OFDM) and filter bank multicarrier (FBMC) have been introduced in VLC systems. The FBMC technique is a promising candidate for the 5G communication system and it has recently been applied to VLC systems. FBMC has several advantages: higher spectrum efficiency, narrower out-of-band radiations and asynchronous transmission. This study investigates the performance of an FBMC-based VLC system when one or more lamps in the multiple LED arrays experience failure. The VLC- FBMC model was implemented using a 4-QAM and 16-QAM format with three various LED array configurations while assuming a line of sight (LOS) model. The LED array model was evaluated based on its ability to achieve good bit error rate (BER) performance, communication quality and high bit rate and meet the required signal-to-noise ratio (SNR). The proposed FBMC model simulation's outcome indicates that the system is still able to transmit data reliably, even in the event of a failure of up to 50% of the lamps. The results indicate that the 2- and 4-lamp models yielded good BER performance, achieving a value of 3.6 × 10−5 and 5.4 × 10−5 respectively. Furthermore, the simulation demonstrated that the optical FBMC-based VLC system attained a high bit rate of 73.2 Mbit/s in the 4-QAM format using the 2-lamp model and a bit rate of 29.3 Mbit/s in 16-QAM format using the 4-lamp model, while maintaining acceptable BER performance.

Machine Learning based modulation format classification framework for inter-satellite optical wireless communication system (IsOWCS)

Abstract The exponential growth in demand for high-capacity optical systems has driven the advancement of advanced modulation formats to upgrade transmission capacity and transmission quality. Effective fault diagnosis and self-configuration in inter-satellite optical wireless communication systems (IsOWCS) depend intensely on the generated data. Machine learning (ML) approaches offer promising solutions in evaluating the execution of these networks. In this study, a dataset was created using OptiSystem 18.0. The dataset was composed of various modulation formats such as duobinary, return-to-zero (RZ), non-return-to-zero (NRZ), 33 % RZ, chirped NRZ, vestigial sideband (VSB) NRZ, carrier-suppressed return-to-zero (CSRZ), and VSB CSRZ. The classification of modulation formats has been presented in this study using ML. The dataset was created by varying input power from 0 to 20 dBm and evaluating parameters such as Q factor, input/output signal-to-noise ratio (SNR), power, range, eye closure, amplitude, height, eye opening, output OSNR. Four ML classifiers were used to predict the classification of different modulation formats. Random forest (RF) classifier performed exceptionally well and achieved 100 % accuracy. Moreover, an interactive user-friendly web page was also developed using Anvil for modulation format classification. The proposed research underscores the significance of selecting the appropriate modulation format to optimize the performance and transmission distance of IsOWCS, subsequently enhancing the operation of high-speed optical communication systems.

A butterfly shape acceptor with rigid skeleton and unique assembly enables both efficient organic photovoltaics and high-speed organic photodetectors

Abstract It remains challenging to design efficient bifunctional semiconductor materials in organic photovoltaic and photodetector devices. Here, we report a butterfly-shaped molecule, named WD-6, which exhibits low energy disorder and small reorganization energy due to its enhanced molecular rigidity and unique assembly with strong intermolecular interaction. The binary photovoltaic device based on PM6:WD-6 achieved an efficiency of 18.41%. Notably, an efficiency of 19.42% was achieved for the ternary device based PM6:BTP-eC9:WD-6. Moreover, the photodetection device based on WD-6 demonstrated an ultrafast response speed (205 ns response time at λ of 820 nm) and a high cutoff frequency of -3 dB (2.45 MHz), surpassing the values of most commercial Si photodiodes. Based on these findings, we show-cased an application of the WD-6-based photodetection device in high-speed optical communication. These results offer valuable insights into the design of organic semiconductor materials capable of simultaneously exhibiting high photovoltaic and photo detective performance.

OFDM system based on parametric DFT transform

This study introduces a specific type of orthogonal frequency division multiplexing (OFDM) system that relies on the parametric discrete Fourier transform (DFT-alpha), where alpha is a parameter randomly selected within the range [-2pi, 0]. We investigate the performance of the proposed system across various channel types and modulation formats, including binary phase shift keying (BPSK), 16 quadratic amplitude modulation (QAM), analyzing aspects such as bit-error rate (BER), peak-to-average power ratio (PAPR), and computational complexity. This work considers the most interesting special case of the one-parameter DFT, which is the DFT-π/6 . The simulated results confirm the suggested OFDM system’s ability to minimize the computational complexity of the conventional OFDM system, standing as the primary contribution of the current study, while maintaining the performance identical. Therefore, the parametric DFT-OFDM system would be a good alternative to the classical DFT-OFDM. The findings suggest that parametric DFT based OFDM holds significant potential for high-speed optical wireless communication systems.

Multi-plane light conversion (MPLC) LP mode multiplexer based on grayscale maskless lithography.

Multi-plane light conversion (MPLC) is a technique that uses multiple phase plates to modulate a light beam step-by-step. This technique has attracted widespread attention in the field of mode-division multiplexing (MDM) communications due to its high flexibility. MPLC device requires precisely controlled fabrication accuracy in experiments, but conventional multi-etching processes will accumulate alignment errors. Here, the fabrication of the MPLC device using maskless grayscale lithography was proposed, which requires only a single-exposure process. Through single-exposure lithography, the continuous phase of the digital mask ranging from 0 to 2π on MPLC is discretized into 128 steps. The digital masks of the MPLC with more steps of phase can reduce the insertion loss and mode crosstalk of LP modes. By using the fabricated MPLC, we experimentally demonstrate the MDM of LP01, LP11a, LP11b, and LP21 modes with mode crosstalk less than -22 dB, and the insertion loss less than 4 dB. In high-speed optical communications, each LP mode carries a 10 Gbit/s on-off keying (OOK) signals, and the experimentally measured bit error rates (BER) curves power penalty is less than -7 dB. The experiment demonstrated that maskless grayscale lithography can efficiently and accurately fabricate MPLC mode multiplexers.

DeepChaos+: Signal Detection Quality Enhancement of High-Speed DP-16QAM Optical Fiber Communication Based on Chaos Masking Technique with Deep Generative Models

DeepChaos+: Signal Detection Quality Enhancement of High-Speed DP-16QAM Optical Fiber Communication Based on Chaos Masking Technique with Deep Generative Models

Bidirectional high-speed optical wireless communication with tunable large field of view assisted by liquid crystal metadevice

Bidirectional high-speed optical wireless communication with tunable large field of view assisted by liquid crystal metadevice

Broadband low-loss polarization-insensitive graphene-integrated photonic crystal fiber modulators in the near-infrared range

The amplitude modulator with the function of converting electric signal to optical amplitude modulation is a key component in high-speed optical communication links. In this paper, we demonstrate a variety of two-dimensional graphene-integrated photonic crystal fiber modulators for efficient near-infrared amplitude modulation with ultra-low insertion loss. Taking the advantages of the perfect total internal reflection of the porous photonic crystal fiber and flexible tunability of the graphene conductivity, the modulation depth of 0.075 dB μm−1 with a low optical loss of 2.13 × 10−4 dB μm−1, a long propagation length of ∼20 mm and polarization-insensitive characteristics in a wide wavelength of 1.3 to 1.8 μm can be achieved. This high-performance modulator may have great potential applications in various high-speed telecommunication, interconnection, and graphene-based integrated photonic systems.

4-Gbps low-latency FPGA-based underwater wireless optical communication.

In this paper, a high-speed and real-time underwater wireless optical communication (UWOC) system based on orthogonal frequency division multiplexing (OFDM) is designed and demonstrated using the field programmable gate array (FPGA) with a miniaturized demo board designed and made by ourselves. Through the parallel signal processing mode (i.e., our self-designed 8-path parallel radix-22 FFT/IFFT module) and the utilization of cyclic suffix (CS) instead of cyclic prefix (CP), the throughput and delay of the digital signal processing (DSP) are improved. Moreover, a low-complexity pilot-aided clock synchronization (PAS) scheme is proposed to solve the transmission errors induced by the frequency offset between the transmitter and receiver. The implementation details, as well as the analysis of resource utilization and latency, are presented. The feasibility and effectiveness of the designed real-time FPGA-based UWOC system in different turbidity waters is experimentally demonstrated. The results show that the proposed PAS scheme greatly reduces the bit error rate (BER) when the frequency offset is within ∼1.57 ppm. Furthermore, 16.3-m/ 2-Gbps and 14.1-m/ 4-Gbps real-time underwater transmission are successfully achieved, which to the best of our knowledge, is the highest data rate in real-time UWOC systems that has ever been reported, and the overall latency of the UWOC system is as low as 0.92 µs. The designed high-speed real-time UWOC system foresees a bright future in underwater applications over short to moderate distances.

Spectrally efficient DWDM system using DQPSK modulation

Abstract DWDM technology is gaining popularity in fiber-optic communication due to high-speed transmission channel capacity demands. The adoption of this system has been driven by this demand. Researchers focus on optimizing data transmission parameters within channel characteristics for maximum performance. The signal’s form typically influences the optical channel capacity, the guiding medium’s dispersive and non-linear characteristics, and interference from multiple sources. This study investigates how efficient modulated systems control linear and non-linear impairments in optical channel capacity due to high data rates transmitted over optical communication networks, aiming to circumvent current issues. The selection of pulse shape and modulation format is crucial for an effective DWDM optical communication system due to the rigorous specifications of the optical channel. Modulation formats like intensity and phase have become viable network design technologies, allowing for network creation that operates to the designer’s satisfaction. This academic study examines the theoretical properties of various models used to analyze and recreate high-speed optical communication links, aiming to understand the impact of system components and modulation techniques.

Optimizing 20 Gbps of ground-to-satellite free-space optical communication in low earth orbit with hybrid wavelength-mode division multiplexing

High-speed free-space optical (FSO) communication has emerged as a promising technology for low earth orbit (LEO) region in the last decade. In this paper, we simulate 20 Gbps simplex ground-to-satellite with various wavelengths and transmitter beam pointing error of 0.1 to 2.5 urad. The C-band wavelength is chosen, and a non-return-zero (NRZ) pulse generator with 16 channels hybrid wavelength-mode division multiplexing (WDM-MDM) technique employing Hermite-Gaussian (HG) modes is used to vary the pointing error. The effect of beam pointing error and receiver aperture diameter was discussed in this paper. A transmitter beam pointing error of 2.5 urad can work appropriately at distances of 1000 km and 1500 km, with a BER value of 1.41 × 10−6 and 3.56 × 10−5, respectively. Based on the receiver aperture diameter of 100 cm, it successfully achieves a BER value of 2.4 × 10−8 at the LEO region and a clear eye diagram.

Performance investigation of UOWC system based on OAM beams for various Jerlov water types

This paper introduces a novel high-speed underwater optical wireless communication (UOWC) system employing three distinct orbital angular momentum (OAM) beams. A single green laser source operating at 532 nm generates these beams: LG0,0,LG0,20,andLG0,50, each transmitting data at 10 Gbps. The paper provides a comprehensive analysis of absorption and scattering coefficients for five Jerlov water types: I (JI), IA (JIA), IB (JIB), II (JII), and III (JIII). Simulation results demonstrate the system ability to transmit multiple data streams simultaneously using distinct OAM modes, achieving an overall capacity of 30 Gbps. The longest underwater (UW) transmission distance of 22 m is achieved in JI water as it exhibits the lowest attenuation. This range decreases by 9.09 %, 31.82 %, 59.09 %, and 80.91 % in JIA, JIB, JII, and JIII, respectively, due to increased attenuation in these water types. These results are obtained with a log (BER) below −5 and a Q-factor above 4, indicating successful data reception. The findings highlight the potential of OAM multiplexing for enhancing data capacity in challenging underwater environments.

Demonstration of a low-complexity real-time FBMC transmitter for a spectral-efficiency IMDD system.

Filter bank multi-carriers (FBMC) have higher spectral efficiency, lower out-of-band spectrum leakage, and stronger ability to resist synchronization errors compared to orthogonal frequency-division multiplexing (OFDM), which has been widely considered as a promising solution for short-reach applications, such as passive optical networks. However, the traditional fast Fourier transform (FFT)-based FBMC scheme has quite high implementation complexity for high-speed optical communications. In this work, we proposed a low-complexity real-time FBMC transmitter scheme enabled by a single fully parallel pruned inverse FFT and simplified short prototype filter-based polyphase networks for a low-cost intensity-modulation and direct-detection (IMDD) system. Compared to the OFDM transmitter, the proposed FBMC one occupies a similar number of look-up tables and registers but saves 21% of real multipliers, reduces latency by 16.2%, and increases the data rate by 12.5%. The real-time FBMC/OFDM signals are generated with a field programmable gate array chip and 6-bit 30-GSa/s digital-to-analog converter and are experimentally demonstrated in an IMDD system. After a 20-km standard single-mode fiber transmission, the negligible power penalty can be achieved with the proposed FBMC transmitter scheme at the bit error rate of 3.8e-3 compared to the OFDM counterpart.

Recent Progresses on Hybrid Lithium Niobate External Cavity Semiconductor Lasers.

Thin film lithium niobate (TFLN) has become a promising material platform for large scale photonic integrated circuits (PICs). As an indispensable component in PICs, on-chip electrically tunable narrow-linewidth lasers have attracted widespread attention in recent years due to their significant applications in high-speed optical communication, coherent detection, precision metrology, laser cooling, coherent transmission systems, light detection and ranging (LiDAR). However, research on electrically driven, high-power, and narrow-linewidth laser sources on TFLN platforms is still in its infancy. This review summarizes the recent progress on the narrow-linewidth compact laser sources boosted by hybrid TFLN/III-V semiconductor integration techniques, which will offer an alternative solution for on-chip high performance lasers for the future TFLN PIC industry and cutting-edge sciences. The review begins with a brief introduction of the current status of compact external cavity semiconductor lasers (ECSLs) and recently developed TFLN photonics. The following section presents various ECSLs based on TFLN photonic chips with different photonic structures to construct external cavity for on-chip optical feedback. Some conclusions and future perspectives are provided.

Preface

We are pleased to present the proceedings of the International Conference on Electronics, Communications, and Intelligent Science (ECIS 2024), held in Changsha, China, from May 24th to 27th, 2024. This conference serves as a platform for academics, researchers, and practitioners to discuss the latest advancements in electronics, communications, and intelligent science. We extend our heartfelt thanks to our guest editors, Professor Yang Yue from Xi’an Jiaotong University and Professor Guan Gui from Nanjing University of Posts and Telecommunications, for their invaluable contributions and work in ensuring the high quality of this publication. Their expertise has been crucial in selecting the research papers presented in this conference. Our gratitude also goes to the Xi’an Jiaotong University, whose support has been instrumental in the successful organization of ECIS 2024. Additionally, we acknowledge the distinguished speakers who have graciously shared their knowledge and insights: Professor Mohammad S. Obaidat, Life Fellow of IEEE, who delivered an enlightening keynote on a new learning automata-based controller placement technique for software-defined network systems; Professor Yang Yue, who discussed high-speed optical communications; Professor Guan Gui, who explored ubiquitous sensing and intelligent identification for 6G wireless communications; and Professor Lei Lei from Nanjing University of Aeronautics and Astronautics, who presented his research on intelligent cooperation theory of unmanned aerial vehicular swarms based on digital twins. We also express our appreciation to the workshop chairs and members, who represent various prestigious institutions, for their efforts in facilitating specialized sessions. Their participation highlights the diversity and richness of the discussions at ECIS 2024. Finally, we thank all the attendees, authors, and reviewers whose active participation and contributions have made this conference a success. We hope that the knowledge shared and the collaborations formed here will continue to drive forward innovations in electronics, communications, and intelligent science. We look forward to your continued engagement in future editions of the conference. The Conference Committee ECIS 2024 List of Conference Committees are available in this Pdf.

TFLN-based nondegenerate optical parametric amplifier with high gain, high saturated optical power and linear wavelength tunability

Optical parametric amplifier (OPA) utilizing thin-film lithium niobate (TFLN) is a cornerstone in integrated microwave optics and high-speed optical communication due to its outstanding properties, including high gain, low noise figure, and high integration. Here, we proposed a pump-depletion nondegenerate amplifier to discuss the saturated optical power. This OPA exhibits a good performance with high gain (over 30 dB) and high saturated optical power (over 15 dBm). The signal frequency is well separated from idle which reduces the difficulties of separation. Meanwhile, we found that the quasi-phase-matching wavelength can be regulated by temperature to achieve a linear adjustable OPA. Detailed design strategies are provided in this paper to underpin the fabrication of high-performance OPA in integrated optics. This theoretical analysis creates opportunities for performance enhancement in microwave photonic links.

Impact of dispersion-shifted fiber on optical communications link through orthogonal channels

Dispersion-Shifted Fiber (DSF) is essential for reducing chromatic dispersion in high-speed optical communication systems. This study investigates the influence of Four Wave Mixing (FWM) on the quality of signals in orthogonal channels. We examine the advantages of DSF technology and analyze the impact of modulation formats such as On-Off Keying with Return-to-Zero (OOK-RZ) and Duo Binary Modulation class-1 (DBM-1) on transmission performance at different distances. This research assesses the efficacy of orthogonal channels in mitigating four-wave mixing (FWM) effects and improving the overall performance of eight-channel systems at distances of 100 km and 200 km through computer simulations. The results of our study show notable enhancements, namely in optimizing the Q-factor (a metric for signal quality) and reducing bit error rates when employing orthogonal channels compared to previous work. By integrating orthogonal channels with OOK-RZ modulation, we achieved higher performance and reduced nonlinear impairments in a simulated eight-channel system with 50 GHz spacing and 80 Gb/s data rates. This effect was particularly pronounced at high input power levels. At an input power of 20 dBm and a distance of 200 km, this particular combination yielded a maximum Q-factor of 27.25 and a minimum FWM power of −54 dBm. In comparison, under the same conditions, the use of OOK-RZ alone resulted in an FWM power of −24 dBm and a Q-factor of only 1.63. This research provides vital insights into enhancing the efficiency and dependability of optical communication systems, hence facilitating breakthroughs in high-speed data transfer and network scalability.