Error-free Data Transmission Research Articles

Improving the efficiency of channel evaluation during high-speed data transmission in underwater acoustic communication with OFDM

Problem statement. The organization of noise-resistant wireless underwater acoustic communication is not a simple and solved task. One of the main problems is the multipath propagation of a sound acoustic wave as a result of re–reflections from the seabed surface and a change in the frequency of signal vibrations when the receiver and transmitter move relative to each other. Thus, finding a channel evaluation solution that can improve the quality of communication is an urgent task for developers of underwater acoustic communication systems. Purpose. To consider the possibility of developing effective methods for processing underwater acoustic communication signals with high noise immunity by evaluating the communication channel. Results. The possibility of using an adaptive filter with a sliding window to evaluate the channel during high-speed data transmission in underwater acoustic communication is shown. The simulation results showed that the proposed adaptive filter with a sliding window surpasses the normalized adaptive filters in terms of the BER bit error and wins over additive filters with an exponential window in reducing the number of mathematical operations. When modeling wireless acoustic communication systems with OFDM, error-free data transmission with a spectral efficiency of 0.33 bits/s/Hz was achieved. Practical significance. The obtained results can be used to improve the wireless transmission of data in underwater acoustic communication due to the proposed algorithm of the adaptive filter.

Overcoming oxygen inhibition in UV photolithography for the fabrication of low-loss polymer waveguides.

Perfluorinated acrylate polymer materials exhibit low absorption loss at 1310 and 1550 nm, but molecular oxygen inhibits their photocuring. We propose a novel, to our knowledge, UV photolithography method incorporating a pre-exposure process for fabricating low-loss perfluorinated acrylate polymer waveguides. During the pre-exposure process, a partially cured thin layer forms on the core layer, effectively overcoming oxygen inhibition in subsequent lithography. Furthermore, the functional group contents of the polymerized materials were characterized by a Raman spectrometer to analyze the development reaction under the pre-exposure layer. Utilizing this improved method, we fabricated a straight waveguide with a length of 21 cm. The experiments showed that the propagation losses are 0.14 dB/cm at 1310 nm and 0.51 dB/cm at 1550 nm. The inter-channel cross talk for a core pitch of 250 µm was measured as low as -49 dB at 1310 nm. Error-free NRZ data transmission over this waveguide at 25 Gb/s was achieved, showcasing the potential in optical interconnect and communication applications.

Error performance analysis of forward error correction using convolutional encoding in the presence of (1/f) noise

Any communication scheme's principal goal is providing error-free data transmission. By increasing the rate at which data could be transmitted through a channel and maintaining a given error rate, this coding is advantageous. The message bits to be transmitted will gradually receive more bits thanks to the convolution (channel) encoder. At the receiver end of the channel, a Viterbi decoder is utilized in order to extract original message sequence from the received data. Widely utilized error correction approaches in communication systems for the enhancement of bit error rate (BER) performance are Viterbi decoding and convolutional encoding. The Viterbi decoder and convolution encoder rate for constraints with lengths of 2 and 6 and bit rates of 1⁄2 and 1⁄3 are shown in this study in the presence of (1/f) noise. The performance regarding the convolutional encoding/hard decision Viterbi decoding forward error correction (FEC) method affects the simulation outcomes. The findings demonstrate that the BER as function of signal to noise ratio (SNR) acquired for uncoded binary phase shift keying (BPSK) with the existence of additive white Gaussian noise (AWGN) is inferior to that acquired with the use of a hard decision Viterbi decoder.

Direct ink writing 3D-printed optical waveguides for multi-layer interconnect.

Low-cost, short-range optical interconnect technology plays an indispensable role in high-speed board-level data communications. In general, 3D printing technology can easily and quickly produce optical components with free-form shapes, while the traditional manufacturing process is complicated and time-consuming. Here, we present a direct ink writing 3D-printing technology to fabricate optical waveguides for optical interconnects. The waveguide core is 3D printed optical polymethylmethacrylate (PMMA) polymer, with propagation loss of 0.21 dB/cm at 980 nm, 0.42 dB/cm at 1310 nm, and 1.08 dB/cm at 1550 nm, respectively. Furthermore, a high-density multilayer waveguide arrays, including a four-layer waveguide arrays with a total of 144 waveguide channels, is demonstrated. Error-free data transmission at 30 Gb/s is achieved for each waveguide channel, indicating that the printing method can produce optical waveguides with excellent optical transmission performance. We believe this simple, low-cost, highly flexible, and environmentally friendly method has great potential for high-speed short-range optical interconnects.

Multi-dimensional data transmission using inverse-designed silicon photonics and microcombs

The use of optical interconnects has burgeoned as a promising technology that can address the limits of data transfer for future high-performance silicon chips. Recent pushes to enhance optical communication have focused on developing wavelength-division multiplexing technology, and new dimensions of data transfer will be paramount to fulfill the ever-growing need for speed. Here we demonstrate an integrated multi-dimensional communication scheme that combines wavelength- and mode- multiplexing on a silicon photonic circuit. Using foundry-compatible photonic inverse design and spectrally flattened microcombs, we demonstrate a 1.12-Tb/s natively error-free data transmission throughout a silicon nanophotonic waveguide. Furthermore, we implement inverse-designed surface-normal couplers to enable multimode optical transmission between separate silicon chips throughout a multimode-matched fibre. All the inverse-designed devices comply with the process design rules for standard silicon photonic foundries. Our approach is inherently scalable to a multiplicative enhancement over the state of the art silicon photonic transmitters.

Photonic crystal resonators for inverse-designed multi-dimensional optical interconnects.

We experimentally demonstrate a 400 Gbit/s optical communication link utilizing wavelength-division multiplexing and mode-division multiplexing for a total of 40 channels. This link utilizes a novel, to the best of our knowledge, 400 GHz frequency comb source based on a chip-scale photonic crystal resonator. Silicon-on-insulator photonic inverse-designed 4 × 4 mode-division multiplexer structures enable a fourfold increase in data capacity. We show less than -10 dBm of optical receiver power for error-free data transmission in 34 out of a total of 40 channels using a PRBS31 pattern.

Superconducting Processor Modulated VCSELs for 4K High-Speed Optical Data Link

Superconducting processor based on single flux quantum (SFQ) technology is a promising solution for cryogenic computing with high-speed operation at extremely low power. However, energy-efficient data link from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 4\text{K}$ </tex-math></inline-formula> operation to room temperature (RT) users has been remained as a key challenger to be resolved. In this work, we report the 5K performance of 51.56 Gb/s PAM-4 optical data link from a VCSEL, coupled by free-space optics inside cryostat to RT receiver through cryostat optical window. Finally, a superconducting bit pattern generator (BPG) is used to modulate a VCSEL at 4 K: 12.5 Gb/s NRZ error-free optical data transmission and 20 Gb/s NRZ open eye-diagrams are demonstrated via an OM4 fiber coupled directly to the VCSEL at 4 K inside cryostat and linked to the outside receiver at RT.

EML Based on Identical Epitaxial Layer, Side-Wall Grating and HSQ Planarization

We present an electroabsorption modulated laser based on an identical epitaxial scheme, side-wall grating, on- chip microwave probe interface, and a new low-permittivity planarization method. The modulation speed is significantly increased by reducing the electrode capacitance by planarizing with a 5-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>-thick HSQ layer. Furthermore, implementing the electrode with a direct ground-signal-ground probe interface provides a straightforward interconnection that obviates the need for an external circuit and bonding wires. The device operates at 1565 nm wavelength with stable single-mode lasing, no mode-hopping, and a side mode suppression ratio above 35 dB. An extinction ratio of 19.5 dB was recorded at the maximum modulator bias of &#x2212;4 V. The electrical to optical power response of the modulated signal at&#x2013;3-dBo demonstrated a 19 GHz bandwidth at an extinction ratio of 7 dB, which supports error-free data transmission up to 27 Gbit/s.

Dynamic characteristics and noise modelling of directly modulated quantum well-dots microdisk lasers on silicon

The small-signal amplitude modulation, threshold, and spectral characteristics of microdisk lasers with InGaAs/GaAs quantum well-dots active region were studied jointly with the spectral and threshold parameters of edge-emitting lasers made from the same epitaxial heterostructure. Using the obtained material parameters, the relative intensity noise of the microdisk lasers was calculated as a function of the bias current and side-mode suppression ratio. It is shown that the integral noise is low enough for error-free optical data transmission with the maximum possible bitrate limited by the microdisk modulation bandwidth, if the bias current is above 1.7× threshold current (for side mode suppression ratio > 20 dB).

Performance Investigation of MIMO Based CO-OFDM FSO Communication Link for BPSK, QPSK and 16-QAM under the Influence of Reed Solomon Codes

The MIMO based CO-OFDM FSO communication system is emerging as a promising approach to meet the future bandwidth requirements for seamless communication. The atmosphere being the propagation medium is a major hindrance in wide-scale acceptability of FSO technology. For seamless and error-free transmission and reception of data, a novel concept of MIMO integrated with RS code is proposed in this paper. The system performance of an RS 64 (RS (255,127)) coded MIMO-based CO-OFDM FSO communication link was investigated using BPSK, QPSK and 16-QAM under the combined effects of geometric losses, path losses and atmospheric attenuations at a hitherto un-investigated data rate of 40 Gbps and a link distance of 5 km. The modified gamma-gamma distribution was used for modeling a moderately turbulent channel. With link length varying over a range of 1 to 5 km, error correction was maximum in 16-QAM as compared to BPSK and QPSK, with 150 to 167 corrected errors. In terms of PAPR, PSK was more apt than QAM, but with a compromise in BER. The geometric losses were reduced with link length due to an increase in error correction capability for all three modulation cases, with the least losses occurring in 16-QAM. At the target bit error rate (BER), the signal to noise ratio (SNR) required for BPSK and QPSK was higher by 3.98 dB and 6.14 dB compared to 16-QAM.

A Secure Mobile Wireless Sensor Networks based Protocol for Smart Data Gathering with Cloud

The lightweight sensors gain rapid growth for the development of emerging technologies due to multi aspects. Recently, many applications are integrating with the cloud services for storage and processing a large amount of observing data, however, the transitory and time-dependent environment needs valuable performance. Also, reliable and error-free data transmission is an important factor for green systems. Moreover, most of the proposed green networks may be exposed to unspecified events due to the broadcast nature of the unreserved medium. This research paper presents a secured mobile sensor network based protocol for smart data gathering with cloud services (S-SDC), which aims to attain information distribution in dynamic networks using mobile sensors with minimum loss and power consumption. Also, it ensures network availability and consistency for the collected data with the cloud corporations and increases authoritative routing. The simulation results and their analysis are proven the significant performance of the proposed protocol.

Impact of Kerr optical frequency comb linewidth on the performance of NRZ-OOK modulated fiber optical communication system

Optical frequency combs (OFCs) generated in microresonators can substitute for widely employed power-hungry laser arrays, ensuring spectral and energy efficiency in wavelength-division multiplexed passive optical networks (WDM-PONs). Here, we propose a realistic design of a WDM-PON based on a silica microresonator generating an OFC in the dissipative Kerr soliton regime and present a corresponding theoretical study, paying particular attention to the impact of the comb linewidth on the characteristics of the communication system. Using intensive numerical simulation, data transmission performance in an eight-channel 100 GHz spaced WDM-PON is investigated for OFC carrier linewidths of 100 kHz, 1 MHz, 10 MHz, and 100 MHz. We show that microresonator-based OFCs with linewidths of up to 100 MHz can be used for a non-return-to-zero on-off keying modulated data transmission system and give an acceptable bit error rate (BER). Results show that the narrower the linewidth, the lower the BER is. The data transmission results show that error-free data transmission is possible with a BER of 4.4 × 10−12 for 100 kHz OFC carrier linewidth, providing 80 Gbps of total data rate on eight OFC generated carriers.

2.6 K VCSEL data link for cryogenic computing

Cryogenic computing requires an energy-efficient optical data link from 4 K to the end-user at room temperature. Laser spectra and light–current–voltage family curves over a wide temperature range from 2.6 to 295 K are reported on oxide-vertical cavity surface emitting lasers coupled with OM4 fiber. Non-linear shifting of the lasing wavelength vs junction temperatures is measured with the wavelength shifting coefficients &amp;lt;0.005 nm/K at 2.6 K. 12.5 Gb/s non-return-to-zero error-free data transmission at 2.6 K to the error detector at 295 K is demonstrated as a viable solution for cryo-computing.

Electrically Parallel Three-Element 980 nm VCSEL Arrays with Ternary and Binary Bottom DBR Mirror Layers.

To meet the performance goals of fifth generation (5G) and future sixth generation (6G) optical wireless communication (OWC) and sensing systems, we seek to develop low-cost, reliable, compact lasers capable of sourcing 5–20 Gb/s (ideally up to 100 Gb/s by the 2030s) infrared beams across free-space line-of-sight distances of meters to kilometers. Toward this end, we develop small arrays of electrically parallel vertical cavity surface emitting lasers (VCSELs) for possible future use in short-distance (tens of meters) free-space optical communication and sensing applications in, for example, homes, data centers, manufacturing spaces, and backhaul (pole-to-pole or pole-to-building) optical links. As a starting point, we design, grow by metal–organic vapor phase epitaxy, fabricate, test, and analyze 980 nm top-emitting triple VCSEL arrays. Via on-wafer high-frequency probe testing, our arrays exhibit record bandwidths of 20–25 GHz, optical output powers of 20–50 mW, and error-free data transmission at up to 40 Gb/s—all extremely well suited for the intended 5G short-reach OWC and sensing applications. We employ novel p-metal and top mesa inter-VCSEL connectors to form electrically parallel but optically uncoupled (to reduce speckle) arrays with performance exceeding that of single VCSELs with equal total emitting areas.

IM/DD WDM-PON Communication System Based on Optical Frequency Comb Generated in Silica Whispering Gallery Mode Resonator

This article reports an implementation of a microsphere-based optical frequency comb (OFC) generator for substitution of individual laser arrays and simulates wavelength division multiplexed passive optical network (WDM-PON) based on this OFC generator. Our proposed generator is built based on silica microsphere, barely studied for fiber optical communication systems, and is a promising solution with photonic integration capability. Kerr OFC as a multiple light source containing more than 20 spectral carriers in the fundamental mode family in the C-band and beyond is demonstrated experimentally. Four of these OFC generator carriers with the highest peak power are studied in simulated 4-channel 393 GHz spaced WDM-PON. Additionally, we show this OFC as a source of optical carriers capable of providing data transmission over most utilized fiber types in modern optical communication systems, namely, single-mode fiber (SMF), non-zero dispersion-shifted fiber (NZ-DSF), and cut-off shifted fiber (CSF). We show through the simulations that error-free data transmission is possible, providing a total transmission capacity of 40 Gbit/s by using four OFC generated carriers.

Sub-60-GHz power-efficient fronthaul system of up to 16-Gbps using RF carriers generated from a gain-switched VCSEL

Future fronthaul wireless networks will be more competitive and attractive if they can use power- and cost-efficient transmitter systems to realize both extended reach and enhanced network capacity. Photonic generation of high-frequency RF carrier signals is currently considered an attractive technique. The laser gain-switching technique for photonic generation of high-frequency RF carrier signals has attracted great interest recently and is a cost-efficient scheme. Vertical cavity surface emitting laser (VCSEL) are power-efficient optical sources requiring bias currents below 10-mA. The use of VCSELs for gain-switched optical frequency comb generation has proven to be attractive in the term of power-efficiency. However, the data transmission performance of these gain-switched VCSEL optical frequency combs are yet to be demonstrated. In this paper, for the first time to our knowledge, we numerically demonstrated that RF carrier signals generated from a gain-switched VCSEL optical frequency comb can support up to16-Gbps error-free data transmission over fiber length beyond 20-km. A 56-GHz RF carrier signal was amplitude-modulated with 10- and 16.3-Gbps data before error-free transmission over 20.5-km of standard single mode fibers. Transmission penalties of 2- and 7-dB were recorded at 10- and 16.3-Gbps, respectively, at receiver sensitivities below -17-dBm.

Microsphere-Based Optical Frequency Comb Generator for 200 GHz Spaced WDM Data Transmission System

Optical frequency comb (OFC) generators based on whispering gallery mode (WGM) microresonators have a massive potential to ensure spectral and energy efficiency in wavelength-division multiplexing (WDM) telecommunication systems. The use of silica microspheres for telecommunication applications has hardly been studied but could be promising. We propose, investigate, and optimize numerically a simple design of a silica microsphere-based OFC generator in the C-band with a free spectral range of 200 GHz and simulate its implementation to provide 4-channel 200 GHz spaced WDM data transmission system. We calculate microsphere characteristics such as WGM eigenfrequencies, dispersion, nonlinear Kerr coefficient with allowance for thermo-optical effects, and simulate OFC generation in the regime of a stable dissipative Kerr soliton. We show that by employing generated OFC lines as optical carriers for WDM data transmission, it is possible to ensure error-free data transmission with a bit error rate (BER) of 4.5 × 10−30, providing a total of 40 Gbit/s of transmission speed on four channels.

PERFORMANCE ANALYSIS OF FSO LINK IN MONSOON (RAINY) SEASON IN DELHI, INDIA

In this paper, we present a comprehensive survey of attenuation due to rain conditions in the months of monsoon in Delhi region. In this paper I used Marshal and Palmer rain distribution model for four specific months of the rainfall i.e. June to September for calculate simulation model for rain attenuation. I analyzed Q-factor of the received signal by varying the transmission wavelength, data rate and range of the FSO system. The simulation results show that for error free transmission of data during the months of rainfall, the transmission signal wavelength in the longer wavelength region at a wavelength of 1300nm and 1550nm is recommended to be used for a maximum data rate of 2.5Gb/s with a maximum transmission range up to 4Km. Delhi being a highly populated (with the IT hub) city the demand for higher and unlimited bandwidth for communication channel is highly required. For this case the communication through FSO is the best alternative solution than optical fiber.

All-photonic 20-MHz clock for latency monitoring in a 5G network at 10 Gbps over optical fiber

Innovation and advancement in technologies such as self-driving cars, machine learning, remote health and factory floor automation have led to extremely stringent next-generation communication requirements. For instance, in a self-driving car, sensor data may be streamed to a cloud-based computer. Decentralized machine learning relying on augmented data may be used to control the vehicle. Large amounts of sensor data, along with the real-time nature of the applications, demand requirements on the 5G networks needed to support applications such as this. Specifications for 5G networks require extremely low end-end latency &lt; 1 m s . This latency requirement is tenfold more stringent than the 4G requirement of &lt; 10 m s . In this paper, we present a novel clock method for tracking and monitoring 5G latency. The method is all-optical, can accurately track &lt; 1 m s latency, and is spectrally efficient. We experimentally demonstrate generation of a 10 Gbps intensity-modulated data signal with 12.3 GHz carrier frequency, embedded with 20 MHz phase-modulated clock. The signal is successfully transmitted over 26.6 km of nonzero dispersion shifted fiber (NZDSF) single-mode fiber at 1550 nm. Error-free forward error correction data transmission was archived with 12.05 dB receiver penalty. Phase noise of − 40.55 d B c / H z and − 77.84 d B c / H z were attained at 1 Hz and 1 kHz offsets, respectively, for the clock.

Baseline 1300 nm dilute nitride VCSELs

Dilute nitride (DN) vertical cavity surface emitting lasers (VCSELs) emitting near 1300 nm exhibit state-of-the-art performance including bandwidths of 10 GHz and a record high error-free data transmission of 12 Gbps. Renewed interest in DN VCSELs stems from emerging applications in kilometer-reach digital communication across optical fiber and across free space via eye safe beams, time-of-flight and structured light sensing, and photonic-electronic integrated circuit optical interconnects. We produce VCSEL wafers in a production molecular beam epitaxy system on 3- and 4-inch diameter GaAs wafers. We report record dynamic performance for our test VCSELs with oxide aperture diameters ranging from 2 to 12 µm.