High-speed Data Communication Research Articles

Real-time, in situ probing of gamma radiation damage with packaged integrated photonic chips

Integrated photonics is poised to become a mainstream solution for high-speed data communications and sensing in harsh radiation environments, such as outer space, high-energy physics facilities, nuclear power plants, and test fusion reactors. Understanding the impact of radiation damage in optical materials and devices is thus a prerequisite to building radiation-hard photonic systems for these applications. In this paper, we report real-time, in situ analysis of radiation damage in integrated photonic devices. The devices, integrated with an optical fiber array package and a baseline-correction temperature sensor, can be remotely interrogated while exposed to ionizing radiation over a long period without compromising their structural and optical integrity. We also introduce a method to deconvolve the radiation damage responses from different constituent materials in a device. The approach was implemented to quantify gamma radiation damage and post-radiation relaxation behavior of SiO 2 -cladded SiC photonic devices. Our findings suggest that densification induced by Compton scattering displacement defects is the primary mechanism for the observed index change in SiC. Additionally, post-radiation relaxation in amorphous SiC does not restore the original pre-irradiated structural state of the material. Our results further point to the potential of realizing radiation-hard photonic device designs taking advantage of the opposite signs of radiation-induced index changes in SiC and SiO 2 .

Architectural Optimization of Parallel Authenticated Encryption Algorithm for Satellite Application

High-speed data communication is becoming essential for many applications, including satellite communication. The security algorithms associated with the communication of information are also required to have high-speed for coping up with the communication speed. Moreover, the Authenticated Encryption (AE) algorithms provide high-speed communication and security services include data encryption, authentication, and integrity. The AE algorithms are available with serial and parallel architectures; among them, the Galois Counter Mode (GCM) algorithm has a parallel architecture. The Synthetic Initialization Vector (SIV) mode in the AES-GCM-SIV algorithm provides the nonce misuse protection using the GCM algorithm. Besides, reduced data throughput is provided using the AES-GCM-SIV algorithm as compared to the AES-GCM algorithm. This work introduced a parallel algorithm with re-keying and randomization of the initialization vector for high data throughput, nonce misuse protection, and side-channel attack protection. The implementation of the proposed algorithm is performed on Field Programmable Gate Array (FPGA) and it’s compared with the FPGA implementations of AES-GCM, AES-GCM-SIV, and recently introduced algorithms. The optimization of the proposed algorithm and security analysis is presented for space application using different optimizations and a combination of optimizations.

Measurement and Analysis of System-Level ESD-Induced Jitter in a Delay-Locked Loop

A delay-locked loop (DLL), which is widely used to compensate for the timing of high-speed data communications, was designed and fabricated in a 180 nm CMOS process. The DLL integrated circuit was assembled on a simplified motherboard and the module structures of a laptop computer and was tested under electrostatic discharge (ESD) events. The input and output voltages of the DLL under ESD-induced noises were measured, and the average values of peak-to-peak jitter and jitter durations of the DLL clock were obtained from repeated measurements. The effects of the voltage-drain-drain (VDD) decoupling capacitors and a bias decoupling capacitor were investigated. SPICE simulations were conducted using the measured input voltages and were compared with the measured results. The root causes of the ESD-induced DLL jitter were identified by analyzing the waveforms from the SPICE simulations. Employing VDD decoupling capacitors and maintaining the amount of delay control parameters for delay cells in the DLL were crucial in reducing jitter. The measured ESD-induced VDD noises were also validated and analyzed using impedance parameter measurements.

Hybrid quantum-dot microring laser on silicon

Future high-performance computers demand highly dynamic data rates, e.g., a few terabytes per second communication bandwidth between switch hubs, and hundreds of gigabytes per second bandwidth between nodes and hubs, in order to overcome the challenges to rapidly growing traffic. Integrated photonic interconnect on silicon is believed to be one of the best solutions for low-cost, energy efficient, and high-speed data communications because of its fundamental advantages in high-volume throughput and dense integration. Applied with signal multiplexing techniques, e.g., wavelength division multiplexing (WDM), large bandwidth data links have been proved to be achievable on silicon. In such a system, an on-chip, robust, low-power consumption laser source is the key component as well as one of the fundamental limits to the silicon platform. In this work, we report the first hybrid silicon microring lasers with quantum-dot (QD) gain material to show great potential for uncooled, highly energy efficient, and isolator-free operation. The hybrid silicon QD lasers have a microring cavity with a 50 μm diameter that incorporates InAs/GaAs QD gain material at a 1.3 μm emission wavelength. The threshold current is as low as 0.7 mA under continuous wave (CW) operation at room temperature, and the laser operates at stage temperatures of up to 70°C. We demonstrate, to the best of our knowledge, a hybrid QD laser with non-return-to-zero (NRZ) communication at a record-high direct modulation rate of 15 Gb/s with energy efficiency of 1.2 pJ/bit. We believe this work shows huge benefits from superior QD lasing material and hybrid photonic integration not only for data communications but also optical memory and many other emerging applications.

Extremely low excess noise and high sensitivity AlAs0.56Sb0.44 avalanche photodiodes

Fast, sensitive avalanche photodiodes (APDs) are required for applications such as high-speed data communications and light detection and ranging (LIDAR) systems. Unfortunately, the InP and InAlAs used as the gain material in these APDs have similar electron and hole impact ionization coefficients (α and β, respectively) at high electric fields, giving rise to relatively high excess noise and limiting their sensitivity and gain bandwidth product1. Here, we report extremely low excess noise in an AlAs0.56Sb0.44 lattice matched to InP. A deduced β/α ratio as low as 0.005 with an avalanche region of 1,550 nm is close to the theoretical minimum and is significantly smaller than that of silicon, with modelling suggesting that vertically illuminated APDs with a sensitivity of −25.7 dBm at a bit error rate of 1 × 10−12 at 25 Gb s−1 and 1,550 nm can be realized. These findings could yield a new breed of high-performance receivers for applications in networking and sensing.

Development, Implementation, and Characterization of a 64-Element Dual-Polarized Phased-Array Antenna Module for 28-GHz High-Speed Data Communications

Silicon-based millimeter-wave (mm-wave) phased-array technologies are enabling directional wireless data communications at Gb/s speeds. In this paper, we review and discuss the challenges of implementing a multichip phased-array antenna module for mm-wave applications using organic buildup substrate technology. A prototype test vehicle has been fabricated and studied to evaluate the antenna and interconnect performance, dielectric properties, package substrate warpage conditions at different temperatures, chip- and board-level joint process reliability, and thermal management feasibility for cooling. Based on the learning from the test vehicle, an organic-based multilayered phased-array antenna package for 28-GHz mm-wave radio access applications is implemented. The package incorporates 64 dual-polarized antenna elements and features an air cavity common to all antennas. Direct probing measurements on a single-antenna element of the package show over 3 GHz of bandwidth and 3-dBi gain at 28 GHz. A phased-array transceiver module has been developed with the package; the module includes four SiGe BiCMOS ICs attached using flip-chip assembly. Module-level measurements in the TX mode show a 35-dB near-ideal output power increase for 64-element power combining; 64-element radiation pattern measurements are reported with a steering range of ± 50° without tapering in off-boresight directions, and 64-element radiation pattern measurements with tapering show achievement of a sidelobe level lower than −20 dB. The transceiver modules achieved 20.64-Gb/s throughput with 256 QAM and 800-MHz bandwidth in direct over-the-air link measurement results.

Superinjection of Holes in Homojunction Diodes Based on Wide-Bandgap Semiconductors.

Electrically driven light sources are essential in a wide range of applications, from indication and display technologies to high-speed data communication and quantum information processing. Wide-bandgap semiconductors promise to advance solid-state lighting by delivering novel light sources. However, electrical pumping of these devices is still a challenging problem. Many wide-bandgap semiconductor materials, such as SiC, GaN, AlN, ZnS, and Ga2O3, can be easily n-type doped, but their efficient p-type doping is extremely difficult. The lack of holes due to the high activation energy of acceptors greatly limits the performance and practical applicability of wide-bandgap semiconductor devices. Here, we study a novel effect which allows homojunction semiconductor devices, such as p-i-n diodes, to operate well above the limit imposed by doping of the p-type material. Using a rigorous numerical approach, we show that the density of injected holes can exceed the density of holes in the p-type injection layer by up to four orders of magnitude depending on the semiconductor material, dopant, and temperature, which gives the possibility to significantly overcome the doping problem. We present a clear physical explanation of this unexpected feature of wide-bandgap semiconductor p-i-n diodes and closely examine it in 4H-SiC, 3C-SiC, AlN, and ZnS structures. The predicted effect can be exploited to develop bright-light-emitting devices, especially electrically driven nonclassical light sources based on color centers in SiC, AlN, ZnO, and other wide-bandgap semiconductors.

Literature Review on BER Improvement of Adaptive Equalizer

Channel equalization is an important aspect in high speed digital communication required for efficient and reliable data recovery and reception when the data is transmitted over band-limited channel subjected to noise and interference. We investigate channel equalization and introduce hierarchical and adaptive nonlinear channel equalization algorithms that are highly efficient and provide significantly improved bit error rate (BER) performance. Due to the high complexity of nonlinear equalizers and poor performance of linear ones, to equalize highly difficult channels, we employ piecewise linear equalizers.

Visible Light Communication: A System Perspective-Overview and Challenges.

Visible light communication (VLC) is a new paradigm that could revolutionise the future of wireless communication. In VLC, information is transmitted through modulating the visible light spectrum (400–700 nm) that is used for illumination. Analytical and experimental work has shown the potential of VLC to provide high-speed data communication with the added advantage of improved energy efficiency and communication security/privacy. VLC is still in the early phase of research. There are fewer review articles published on this topic mostly addressing the physical layer research. Unlike other reviews, this article gives a system prespective of VLC along with the survey on existing literature and potential challenges toward the implementation and integration of VLC.

Mixed-Signal Overclocked I/O Buffers Model Abstraction for Signal Integrity Assessment

This paper addresses the development of a behavioral modeling abstraction methodology that reduces the model order complexity of the transistor level physical model describing the input–output (I/O) buffers that interface the digital (i.e., discrete) and the analog world in the high-speed digital communication I/O links. In fact, the proposed high-level hybrid automaton behavioral model (HABM) is analyzed as a mixed-signal modeling approach that combines both discrete and continuous abstractions. The modeling framework investigates the quantization of the on–off nonreturn-to-zero input signal to analyze the mixed signal behavior of the predriver and the analog dynamics of the I/O buffer’s last stage for easing the model’s extraction and running complexities while accurately predicting the I/O buffer’s nonlinear switching behavior under normal and overclocking conditions. The time decomposition of the input and state variables enables the approximation of the predriver’s nonlinear dynamic by means of digitally controlled linear dynamic filters. The filter’s outputs are multiplexed and integrated with the continuous-time nonlinear dynamic model of driver’s last stage output admittances. The implemented mixed-signal HABM presents more accurate transient simulation results than the I/O buffer information specification algorithm when assessing the signal integrity performance while alleviating the computational cost under overclocking operation.

Optimization of multi-gigabit transceivers for high speed data communication links in HEP Experiments

The scheme of the data acquisition (DAQ) architecture in High Energy Physics (HEP) experiments consist of data transport from the front-end electronics (FEE) of the online detectors to the readout units (RU), which perform online processing of the data, and then to the data storage for offline analysis. With major upgrades of the Large Hadron Collider (LHC) experiments at CERN, the data transmission rates in the DAQ systems are expected to reach a few TB/sec within the next few years. These high rates are normally associated with the increase in the high-frequency losses, which lead to distortion in the detected signal and degradation of signal integrity. To address this, we have developed an optimization technique of the multi-gigabit transceiver (MGT) and implemented it on the state-of-the-art 20 nm Arria-10 FPGA manufactured by Intel Inc. The setup has been validated for three available high-speed data transmission protocols, namely, GBT, TTC-PON and 10 Gbps Ethernet. The improvement in the signal integrity is gauged by two metrics, the Bit Error Rate (BER) and the Eye Diagram. It is observed that the technique improves the signal integrity and reduces BER. The test results and the improvements in the metrics of signal integrity for different link speeds are presented and discussed.

Fast and Accurate Decomposition of Deterministic Jitter Components in High-Speed Links

In a high-speed digital communication system, jitter performance plays a crucial role in bit-error rate. It is important to accurately derive each type of jitter as well as total jitter and to identify root causes of jitter by jitter decomposition as a key tool. In this paper, we extend our previously reported algorithm to decompose duty cycle distortion as well as other deterministic jitter components including periodic jitter (PJ), intersymbol interference (ISI), and random jitter (RJ), and describe more detail of this algorithm with extensively simulation and measurements to verify the algorithm. The proposed ISI model only requires the time invariant condition, which is true for almost all systems, while the traditional ISI model is valid only with linear time invariant assumption. Compared to the conventional methods, the proposed jitter decomposition method is able to obtain estimated individual jitter component values with good accuracy by using fewer samples of total jitter data. The efficiency and accuracy of the proposed method were demonstrated by simulation and hardware experiments.

OFDM Signal Recovery in Deep Faded Erasure Channel

In high-speed digital wireless communication applications, the intersymbol interference channel may have spectral nulls or erasures, which may degrade the orthogonal frequency division multiplexing (OFDM) bit error rate (BER) performance. In this paper, we prove that the BER performance of the OFDM system is considerably refined if the erased symbols in erasure channel (or received symbols on the deep-faded subcarriers in Rayleigh fading channel) are estimated based on the rest symbols in each OFDM signal. Also, an oversampled OFDM scheme which is a particular form of the pre-coded OFDM schemes is considered to guarantee high enough sampling rate. Furthermore, a new iterative receiver is proposed for perfect symbol recovery. A comprehensive Monte Carlo simulation study is performed to validate the theoretical results and affirm the superior performance of the oversampled OFDM scheme with the iterative receiver, compared with the typical detector for the OFDM scheme.

Minimizing the Jitter of Duty Cycle Distortion Correction Technology Based on Cross Point Eye Diagram Correction

Pattern jitter is a primary contributor to the increase of the bit error rate (BER) in high-speed communications, which occurs in large part due to duty cycle distortion (DCD). By considering DCD caused by transmission links and the distribution of jitter in DCD due to the pattern of the transmission link, this paper proposes a precise control method based on the cross point of the eye diagram to minimize the jitter associated with DCD and to effectively decrease the BER of high-speed digital communications. By capitalizing on the theoretical basis that the main form of DCD is the offset of the cross point of the eye diagram, the technology presented here reconstructs the pattern waveform by using a digital method and incorporates a time variable to precisely control the data edge position during the reconstruction process, thereby stabilizing the cross point at 50% to correct its drift. Accordingly, after fanning out the original pattern buffer and then passing two controllable delay lines with different delays through the buffer in a process that is driven by digital logic operation, the cross point of the waveform is reconstructed by changing the relative time delay of the two signals. As a result, the change in the position of the cross point of the eye diagram is transformed into the precise control of the relative time delay, minimizing the DCD jitter. The theoretical model is verified by experiments, indicating that this method can control the cross point of the non-return-to-zero (NRZ) pattern in the range of 30% to 70% under 3 Gbps with a resolution as great as 1%. Furthermore, this approach can solve the problem of cross point drift of the eye diagram and can significantly decrease the BER caused by DCD jitter.

Visible Light Communication Survey

Communication applying visible light technology is a novel approach. Visible Light Communication (VLC) development is motivated by the increasing demand for wireless communication technologies. It has the potential to provide highspeed data communication with good security and improved energy efficiency. The rapid evolution of VLC was sustained by the LEDs performances. The Light-Emitting-Diode (LED) luminaires are capable of switching to the different light intensity at a fast rate. This function can be used for data transmission. This article focuses on the physical layer of the VLC links. It reviews the technology, the topology of the proposed connection, and the benefits of this approach. The main research trends are identified emphasizing state of the art in this area. It shows how VLC technology evolved and what are the performances achieved at this time. Various structures of the transmitter and receiver are studied, and different modulation schemes are investigated. Finally, numerous applications of VLC technology are presented.

ANALISA PERBANDINGAN DALAM RANGKA PEMILIHAN BEBERAPA IP UPSTREAM PROVIDER DI PT. INDOSAT

Abstract. One of the advances in information technology that now has changed the outlook and human life, business process and business strategy of an institution is the internet. The internet is a very large networks that connected to computers and serves throughout the world in one centralized network. With the internet we can access data and information anytime and anywhere. As one provider of high-speed data communications services and the pioneer of the internet network service provider in Indonesia that provides integrated services, as well as one of the pioneer development of internet services that provide extensive services in the building and apply it throughout Indonesia. Indosat ready to seize opportunities for sustainable growth of business spectrum are still sprawling Indonesia. Therefore, Indosat continues to focus on the development of increased efforts to provide the best service for customers of Indosat. Indosat will continue to develop and expand network coverage and a larger investment that the company will achieve excellence in the field of integrated telecommunications services. Ranking by region of the IP Providers can be seen by grouping IP Providers, and management over IP Providers prefer to choose providers based on where it orginates as an example for the region of the U.S if it will be preferred providers that come from U.S. providers.With the commencement of the internet network optimization start early in 2008 with the selection of the appropriate IP Upstream Provider criteria, it is up to date according to data obtained from Indosat, seen any significant changes to the cost of purchasing capacity of the IP Upstream. Based on the data obtained that until Q3 or September 2008, the number of IP Upstream Providers that previously there were 20 to 10 IP Upstream Provider, IP Transit Price total decrease of 11% to the price of IP Transit Price / Mbps there is a decrease of 78%, while from the capacity bandwith an increase of 301% capacity from 2008.

Physical Layer Cryptographic Key Generation by Exploiting PMD of an Optical Fiber Link.

We present a symmetric physical layer based secret key generation scheme for Point-to-Point Optical Link (PPOL) communication by exploiting Polarization Mode Dispersion (PMD) as a random and inimitable channel characteristic. The randomness and security strength of generated cryptographic keys based on PMD is significantly high. In this paper, we present that random modulation of a probe signal caused by PMD in a high-speed data communication network (40Gb/s and 60Gb/s) is reciprocal with average Pearson correlation coefficient of 0.862, despite the presence of optical nonlinearities, dispersion, and noise in the system. 128-bit symmetric cryptographic key has been successfully generated using the proposed scheme. Moreover, PMD based encryption keys passed the National Institute of Standards and Technology (NIST) tests. We have shown through simulations with a 50km link that, with optimal key generation settings, symmetric keys can be generated with high randomness (high P-values for NIST randomness tests) and with sufficient generation rates (>50%). Furthermore, we considered an attack model of a non-invasive adversary intercepting at 10km into the link and found that the generated keys have high average key bit mismatch rates (>40%).

Investigation and Suppression of Fiber Nonlinearities Using Injection-Locking in OFDM-WDM System

The fiber nonlinearities play a major role in optical communication with respect to the system performance and transmission capacity. Here, fiber nonlinear impairments are investigated through consideration of several parameters of optical fiber system, such as fiber length and core effective area. We also demonstrate the mitigation of fiber nonlinearities by using single-stage injection-locking in 3 × 10 Gb/s OFDM-WDM system. This paper focuses on selection of appropriate bias current for slave laser to suppress the four wave mixing (FWM) crosstalk effects. These findings resemble the importance of single-stage injection-locking for FWM suppression for high-speed data communication.

Spin polarization modulation for high-speed vertical-cavity surface-emitting lasers

The spin polarization modulation in birefringent vertical-cavity surface-emitting lasers (VCSELs) is investigated theoretically and experimentally for obtaining tailored polarization modulation characteristics suitable for high-speed data communications. A spin-flip rate equation analysis reveals that the spin polarization modulation response of VCSELs is flattened by shortening the electron spin relaxation time and its 3-dB bandwidth is broadened to a range determined by a frequency split between two orthogonal polarization modes. Optical modulations of spin polarized electrons in commercially-available InAlGaAs quantum well VCSELs demonstrate a wide 3-dB bandwidth of 23 GHz determined by the frequency split, which indicates that the spin relaxation time in the InAlGaAs quantum well VCSEL is around 20 ps at room temperature and suitable for use in high-speed data communications at a telecom wavelength of 1.55 μm.

Negative Frequency-Chirped 112-Gb/s PAM-4 Using an Integrated Germanium Franz-Keldysh Modulator

Integrated germanium-on-silicon Franz–Keldysh modulators (Ge-EAMs) offer a small footprint and low-energy-per-bit performance for high-speed data communications. In this letter, we study the use of Ge-EAMs for four-level pulse amplitude modulation (PAM-4), and report on the linearity of the modulator in terms of its spurious-free dynamic range. The experimental results show that the negative frequency chirp from the modulator can improve the transmission distance of the PAM-4 signal. Using pre-equalization with a 25-GHz bandwidth-limited arbitrary waveform generator, we obtained a data rate of 112 Gb/s with a bit-error-rate of $2.5\times 10^{-3}$ under the 7% overhead hard-decision forward error correction threshold. We observed an extended transmission distance in our 112-Gb/s PAM-4 experiment on a standard single-mode fiber thanks to the negative frequency chirp of the modulator.